Human evolution by martin
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About This Presentation
Human evolution is the evolutionary process leading up to the appearance of modern humans. It is the process by which human beings developed on Earth from now-extinct primates. It involves the lengthy process of change by which people originated from apelike ancestors. The study of human evolution i...
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HUMAN EVOLUTION
By
M.N.O.UWAMOSE
DEPARTMENT OF ANIMAL AND ENVIRONMENTAL BIOLOGY,
FACULTY OF SCIENCE,
DELTA STATE UNIVERSITY, ABRAKA.
February, 2014
By
M.N.O.UWAMOSE
DEPARTMENT OF ANIMAL AND ENVIRONMENTAL BIOLOGY,
FACULTY OF SCIENCE,
DELTA STATE UNIVERSITY, ABRAKA.
February, 2014
pg.2
TABLE OF CONTENT
1.0Introduction
2.0Evolutionary Theory
3.0Processof Evolution
4.0History of Human Evolution
5.0Paleoanthropology
6.0Evidence of Evolution
6.1Evidence from comparative physiology
6.2Evidence from comparative anatomy
6.3Evidence from comparative embryology
6.4Evidence from comparative morphology
6.5Evidence from vestigial organs
6.6Genetics
6.7Evidence from Molecular Biology
6.8Evidence from the Fossil Record
7.0Divergence of the Human Clade fromother Great Apes
8.0Anatomical changes
8.1Anatomy of bipedalism
8.2Encephalization
8.3Sexual dimorphism
8.4Other changes
9.0GenusHomo
10.0Homo Sapiens Taxonomy
11.0Conclusion
12.0References
TABLE OF CONTENT
1.0Introduction
2.0Evolutionary Theory
3.0Processof Evolution
4.0History of Human Evolution
5.0Paleoanthropology
6.0Evidence of Evolution
6.1Evidence from comparative physiology
6.2Evidence from comparative anatomy
6.3Evidence from comparative embryology
6.4Evidence from comparative morphology
6.5Evidence from vestigial organs
6.6Genetics
6.7Evidence from Molecular Biology
6.8Evidence from the Fossil Record
7.0Divergence of the Human Clade fromother Great Apes
8.0Anatomical changes
8.1Anatomy of bipedalism
8.2Encephalization
8.3Sexual dimorphism
8.4Other changes
9.0GenusHomo
10.0Homo Sapiens Taxonomy
11.0Conclusion
12.0References
pg.3
1.0INTRODUCTION
Evolutionis the genetic transformation of populations over time. In this sense,
a population is a group of living thingswhichrandomly mate with one another.
A species onthe other hand is a group of populations whose members can
interbreed. If two populations of a species are separated and growngenetically
apart they won't be able to produce fertile offspring together anymore. It is at
this point where they become different species.
Human evolutionis the evolutionary process leading up to the appearance of
modern humans. It is the process by which human beings developed on Earth
from now-extinct primates. It involvesthe lengthy process of change by which
people originated from apelike ancestors.The study of human evolution
involves many scientific disciplines, including physical anthropology,
primatology, archaeology, ethology, evolutionary psychology, embryology and
genetics.Scientific evidence shows that the physical andbehaviouraltraits
shared by all people originated from apelike ancestors and evolved over a
period ofapproximately six million years.
2.0EVOLUTIONARY THEORY
Before evolutionary theory was developed, the general consensus in the world
was based on religious doctrine, which was that species did not changefrom
1.0INTRODUCTION
Evolutionis the genetic transformation of populations over time. In this sense,
a population is a group of living thingswhichrandomly mate with one another.
A species onthe other hand is a group of populations whose members can
interbreed. If two populations of a species are separated and growngenetically
apart they won't be able to produce fertile offspring together anymore. It is at
this point where they become different species.
Human evolutionis the evolutionary process leading up to the appearance of
modern humans. It is the process by which human beings developed on Earth
from now-extinct primates. It involvesthe lengthy process of change by which
people originated from apelike ancestors.The study of human evolution
involves many scientific disciplines, including physical anthropology,
primatology, archaeology, ethology, evolutionary psychology, embryology and
genetics.Scientific evidence shows that the physical andbehaviouraltraits
shared by all people originated from apelike ancestors and evolved over a
period ofapproximately six million years.
2.0EVOLUTIONARY THEORY
Before evolutionary theory was developed, the general consensus in the world
was based on religious doctrine, which was that species did not changefrom
pg.4
generations to generations.Some churches still maintains that there was a
special and independent creation of species they known as Creationism which
was from the Judeo-Christian bible.During the Renaissance however,
scientists started looking at nature in a more open-minded way. Over time they
collected evidence that species did in fact change over time.
The possibility of linking humans with earlier apes by descent became clear
only after 1859 with the publication of Charles Darwin'sOn the Origin of
Species, in which he argued for the idea of the evolution of new species from
earlier ones. Darwin's book did not address the question of human evolution,
saying only that "Light will be thrown on the origin of man and his history".
It was Charles Darwin (1809-82) however who developedthe theory of natural
selection which is still supported today. He was able to observe and notice
while doing field research work that members of a population had different
traits among them. Thinking of about this, he realized that these variations in
trait must be more useful for survival than others. He also realized that the
individuals with the most favorable trait based on the environment, was more
likely to survive and pass on the favorable trait to their offspring, thereby
increasing its prevalencein the population.
The first debates about the nature of human evolution arose between Thomas
Huxley and Richard Owen. Huxley argued for human evolution from apes by
generations to generations.Some churches still maintains that there was a
special and independent creation of species they known as Creationism which
was from the Judeo-Christian bible.During the Renaissance however,
scientists started looking at nature in a more open-minded way. Over time they
collected evidence that species did in fact change over time.
The possibility of linking humans with earlier apes by descent became clear
only after 1859 with the publication of Charles Darwin'sOn the Origin of
Species, in which he argued for the idea of the evolution of new species from
earlier ones. Darwin's book did not address the question of human evolution,
saying only that "Light will be thrown on the origin of man and his history".
It was Charles Darwin (1809-82) however who developedthe theory of natural
selection which is still supported today. He was able to observe and notice
while doing field research work that members of a population had different
traits among them. Thinking of about this, he realized that these variations in
trait must be more useful for survival than others. He also realized that the
individuals with the most favorable trait based on the environment, was more
likely to survive and pass on the favorable trait to their offspring, thereby
increasing its prevalencein the population.
The first debates about the nature of human evolution arose between Thomas
Huxley and Richard Owen. Huxley argued for human evolution from apes by
pg.5
illustrating many of the similarities and differences between humans and apes,
and did soparticularly in his 1863 bookEvidence as to Man's Place in Nature.
However, many of Darwin's early supporters (such as AlfredRussellWallace
and Charles Lyell) did not initially agree that the origin of the mental capacities
and the moral sensibilitiesof humans could be explained by natural selection,
though this later changed. Darwin applied the theory of evolution and sexual
selection to humans when he publishedThe Descent of Manin 1871.
3.0PROCESSOF EVOLUTION
The process of evolution involves a series of natural changes that cause species
(populations of different organisms) to arise, adapt to the environment, and
become extinct. All species or organisms have originated through the process
of biological evolution. In animals that reproduce sexually, including humans,
the term species refers to a group whose adult members regularly interbreed,
resulting in fertile offspring i.e., offspring themselves are capable of
reproducing. Scientists classify each species with a unique, two-part scientific
name. In this system, modern humans are classified as Homo sapiens.
Evolution occurs when there is change in the genetic material the chemical
molecule, DNA which is inherited from the parents, and especially in the
proportions of different genes in a population. Genes represent the segments of
DNA that provide the chemical code for producing proteins. Information
illustrating many of the similarities and differences between humans and apes,
and did soparticularly in his 1863 bookEvidence as to Man's Place in Nature.
However, many of Darwin's early supporters (such as AlfredRussellWallace
and Charles Lyell) did not initially agree that the origin of the mental capacities
and the moral sensibilitiesof humans could be explained by natural selection,
though this later changed. Darwin applied the theory of evolution and sexual
selection to humans when he publishedThe Descent of Manin 1871.
3.0PROCESSOF EVOLUTION
The process of evolution involves a series of natural changes that cause species
(populations of different organisms) to arise, adapt to the environment, and
become extinct. All species or organisms have originated through the process
of biological evolution. In animals that reproduce sexually, including humans,
the term species refers to a group whose adult members regularly interbreed,
resulting in fertile offspring i.e., offspring themselves are capable of
reproducing. Scientists classify each species with a unique, two-part scientific
name. In this system, modern humans are classified as Homo sapiens.
Evolution occurs when there is change in the genetic material the chemical
molecule, DNA which is inherited from the parents, and especially in the
proportions of different genes in a population. Genes represent the segments of
DNA that provide the chemical code for producing proteins. Information
pg.6
contained in the DNA can change by a process known as mutation. The way
particular genes are expressed i.e., how they influence the body orbehaviourof
an organism can also change. Genes affect how the body andbehaviourof an
organism develop during its life, and this is why genetically inherited
characteristics can influence the likelihood of an organism’s survival and
reproduction.
Evolution does not change any single individual. Instead, it changes the
inherited means of growth and development that typify a population. Parents
pass adaptive genetic changes to their offspring, and ultimately these changes
become common throughout a population. As a result, the offspring inherit
those genetic characteristics thatenhance their chances of survival and ability
to give birth, which may work well until the environment changes. Over time,
genetic change can alter a species' overall way of life, such as what it eats, how
it grows, and where it can live. Human evolutiontook place as new genetic
variations in early ancestor populations favoured new abilities to adapt to
environmental change and so altered the human way of life.
4.0HISTORY OF HUMAN EVOLUTION
The first members of the human family, Hominidae, first evolvedin Africa,
and much of human evolution occurred on that continent. The fossils of early
humans who lived between 4 and 6 million years ago come entirely from
contained in the DNA can change by a process known as mutation. The way
particular genes are expressed i.e., how they influence the body orbehaviourof
an organism can also change. Genes affect how the body andbehaviourof an
organism develop during its life, and this is why genetically inherited
characteristics can influence the likelihood of an organism’s survival and
reproduction.
Evolution does not change any single individual. Instead, it changes the
inherited means of growth and development that typify a population. Parents
pass adaptive genetic changes to their offspring, and ultimately these changes
become common throughout a population. As a result, the offspring inherit
those genetic characteristics thatenhance their chances of survival and ability
to give birth, which may work well until the environment changes. Over time,
genetic change can alter a species' overall way of life, such as what it eats, how
it grows, and where it can live. Human evolutiontook place as new genetic
variations in early ancestor populations favoured new abilities to adapt to
environmental change and so altered the human way of life.
4.0HISTORY OF HUMAN EVOLUTION
The first members of the human family, Hominidae, first evolvedin Africa,
and much of human evolution occurred on that continent. The fossils of early
humans who lived between 4 and 6 million years ago come entirely from
pg.7
Africa. They spent much of their time in trees, as their close primate relatives
did, who are theancestors of today's chimpanzees and gorillas. But unlike
other primates, the early hominids walked readily on two legs when on the
ground (Bipedalism), one of the earliest traits often used to define the human
family. Anthropologists and evolutionary biologists agree that upright posture
and the subsequent ability to walk on two legs was a crucial major adaptation
associated with the divergence of the human lineage from a common ancestor
with the African apes.
Other important human characteristics such asa large and complex brain, the
ability to make and use tools, and the capacity for language developed more
recently. Many advanced traits including complex symbolic expression, art,
and elaborate cultural diversity emerged mainly during the past 100,000 years.
Between the time of the first hominids and the period when our species, Homo
sapiens, evolved in Africa, our planet was home to a wide range of early
humans. Physical and genetic similarities show that the modern human species,
Homo sapiens, has a very close relationship to another group of primate
species, the apes. Humans and the great apes (large apes) of Africa, the
chimpanzees (including bonobos, or so-called “pygmy chimpanzees”) and
gorillas share a common ancestor that lived between 6 and 8 million years ago.
Africa. They spent much of their time in trees, as their close primate relatives
did, who are theancestors of today's chimpanzees and gorillas. But unlike
other primates, the early hominids walked readily on two legs when on the
ground (Bipedalism), one of the earliest traits often used to define the human
family. Anthropologists and evolutionary biologists agree that upright posture
and the subsequent ability to walk on two legs was a crucial major adaptation
associated with the divergence of the human lineage from a common ancestor
with the African apes.
Other important human characteristics such asa large and complex brain, the
ability to make and use tools, and the capacity for language developed more
recently. Many advanced traits including complex symbolic expression, art,
and elaborate cultural diversity emerged mainly during the past 100,000 years.
Between the time of the first hominids and the period when our species, Homo
sapiens, evolved in Africa, our planet was home to a wide range of early
humans. Physical and genetic similarities show that the modern human species,
Homo sapiens, has a very close relationship to another group of primate
species, the apes. Humans and the great apes (large apes) of Africa, the
chimpanzees (including bonobos, or so-called “pygmy chimpanzees”) and
gorillas share a common ancestor that lived between 6 and 8 million years ago.
pg.8
Scientists over the years are able to understand the story through wealth of
evidence including fossils, artefacts and DNA analysis.
Most scientists currently recognize some 15 to 20 different species of early
humans. Scientists do not all agree, however, about how these species are
related or which ones simply died out. Many early human species certainly the
majority of them left no living descendants. Scientists also debate over how to
identify and classify particular species of early humans, and about what factors
influenced the evolution and extinction of each species.
Early humans first migrated out of Africa into Asia probably between 2 million
and 1.8 million years ago. They entered Europe somewhat later, between 1.5
million and 1 million years. Species of modern humans populated many parts
of the world much later. For instance, people first came to Australia probably
within the past 60,000 years and to the Americas within the past 30,000 years
or so. The beginnings of agriculture and the rise of the first civilizations
occurred within the past 12,000 years.
5.0PALEOANTHROPOLOGY
Paleoanthropology is the scientific study of human evolution.
Paleoanthropology is a subfield of anthropology, the study of human culture,
society, and biology. The field involves an understanding of the similarities
Scientists over the years are able to understand the story through wealth of
evidence including fossils, artefacts and DNA analysis.
Most scientists currently recognize some 15 to 20 different species of early
humans. Scientists do not all agree, however, about how these species are
related or which ones simply died out. Many early human species certainly the
majority of them left no living descendants. Scientists also debate over how to
identify and classify particular species of early humans, and about what factors
influenced the evolution and extinction of each species.
Early humans first migrated out of Africa into Asia probably between 2 million
and 1.8 million years ago. They entered Europe somewhat later, between 1.5
million and 1 million years. Species of modern humans populated many parts
of the world much later. For instance, people first came to Australia probably
within the past 60,000 years and to the Americas within the past 30,000 years
or so. The beginnings of agriculture and the rise of the first civilizations
occurred within the past 12,000 years.
5.0PALEOANTHROPOLOGY
Paleoanthropology is the scientific study of human evolution.
Paleoanthropology is a subfield of anthropology, the study of human culture,
society, and biology. The field involves an understanding of the similarities
pg.9
and differences between humans and other species in their genes, body form,
physiology, andbehaviour. Paleoanthropologists search for the roots of human
physical traits andbehaviour. They seek to discover how evolution has shaped
the potentials, tendencies, and limitations of all people.
Paleoanthropology is an exciting scientific field because it investigates the
origin, over millions of years, of the universal and defining traits of our
species. However, some people find the concept of human evolution troubling
because it can seem not to fitwith religious and other traditional beliefs about
how people, other living things, and the world came to be. Nevertheless, many
people have come to reconcile their beliefs with the scientific evidence. Early
human fossils and archaeological remains offerthe most important clues about
this ancient past. These remains include bones, tools and any other evidence
(such as footprints, evidence of hearths, or butchery marks on animal bones)
left by earlier people. Usually, the remains were buried and preserved
naturally. They are then found either on the surface (exposed by rain, rivers,
and wind erosion) or by digging in the ground. By studying fossilized bones,
scientists learn about the physical appearance of earlier humans and how it
changed. Bone size, shape, and markings left by muscles tell us how those
predecessors moved around, held tools, and how the size of their brains
changed over a long time.
and differences between humans and other species in their genes, body form,
physiology, andbehaviour. Paleoanthropologists search for the roots of human
physical traits andbehaviour. They seek to discover how evolution has shaped
the potentials, tendencies, and limitations of all people.
Paleoanthropology is an exciting scientific field because it investigates the
origin, over millions of years, of the universal and defining traits of our
species. However, some people find the concept of human evolution troubling
because it can seem not to fitwith religious and other traditional beliefs about
how people, other living things, and the world came to be. Nevertheless, many
people have come to reconcile their beliefs with the scientific evidence. Early
human fossils and archaeological remains offerthe most important clues about
this ancient past. These remains include bones, tools and any other evidence
(such as footprints, evidence of hearths, or butchery marks on animal bones)
left by earlier people. Usually, the remains were buried and preserved
naturally. They are then found either on the surface (exposed by rain, rivers,
and wind erosion) or by digging in the ground. By studying fossilized bones,
scientists learn about the physical appearance of earlier humans and how it
changed. Bone size, shape, and markings left by muscles tell us how those
predecessors moved around, held tools, and how the size of their brains
changed over a long time.
pg.10
During the 1960s and 1970s, hundreds of fossils were found, particularly in
East Africa in the regions of the Olduvai Gorge and Lake Turkana. The driving
force in the East African researches was the Leakey family, with Louis Leakey
and his wife Mary Leakey, and later their son Richard and daughter in-law
Meave being among the most successful fossil hunters and
paleoanthropologists. From the fossil beds of Olduvai and Lake Turkana they
amassed fossils of australopithecines, earlyHomoand evenHomo erectus.
These finds cemented Africa as the cradle of humankind. In the 1980s,
Ethiopia emerged as the new hot spot of palaeoanthropology as "Lucy", the
most complete fossil member of the speciesAustralopithecus afarensis, was
found by Donald Johanson in Hadar inthe desertic Middle Awash region of
northern Ethiopia. This area would be the location of many new hominin
fossils, particularly those uncovered by the teams of Tim White in the 1990s,
such asArdipithecus ramidus.
6.0EVIDENCE OFEVOLUTION
According toCharles Darwin, (The Descent of Man and Selection in Relation
to Sex, 2
nd
edition) he who wishes to decide whether man is the modified
descendant of some pre-existing form, would probably first enquire whether
man varies, however slightly, in bodily structure and in mental faculties; and if
During the 1960s and 1970s, hundreds of fossils were found, particularly in
East Africa in the regions of the Olduvai Gorge and Lake Turkana. The driving
force in the East African researches was the Leakey family, with Louis Leakey
and his wife Mary Leakey, and later their son Richard and daughter in-law
Meave being among the most successful fossil hunters and
paleoanthropologists. From the fossil beds of Olduvai and Lake Turkana they
amassed fossils of australopithecines, earlyHomoand evenHomo erectus.
These finds cemented Africa as the cradle of humankind. In the 1980s,
Ethiopia emerged as the new hot spot of palaeoanthropology as "Lucy", the
most complete fossil member of the speciesAustralopithecus afarensis, was
found by Donald Johanson in Hadar inthe desertic Middle Awash region of
northern Ethiopia. This area would be the location of many new hominin
fossils, particularly those uncovered by the teams of Tim White in the 1990s,
such asArdipithecus ramidus.
6.0EVIDENCE OFEVOLUTION
According toCharles Darwin, (The Descent of Man and Selection in Relation
to Sex, 2
nd
edition) he who wishes to decide whether man is the modified
descendant of some pre-existing form, would probably first enquire whether
man varies, however slightly, in bodily structure and in mental faculties; and if
pg.11
so, whether the variations are transmitted to his offspring in accordance with
the laws whichprevail with the lower animals.
The evidence on which scientific accounts of human evolution is based comes
from many fields of natural science. The main sources of knowledge about the
evolutionary process has traditionally been the fossil record, but since the
development of genetics beginning in the 1970s, DNA analysis has come to
occupy a place of comparable importance. The studies of ontogeny, phylogeny
and especially evolutionary developmental biology of both vertebrates and
invertebrates offer considerable insight into the evolution of all life, including
how humans evolved.
6.1Evidence from comparative physiology
Many basic similarities in physiologic and chemical properties parallel the
morphologic features of organisms.
Many individual digestive enzymes present in different animals are essentially
alike in physiologic action. Trypsin, which acts upon proteins, occurs in many
animals right from protozoans to man, an amylase, which acts on starches, is
present from sponges to mammals.
Some hormones derived from endocrine glands show like reactions when
injected into different animals.The thyroid gland present in all vertebrates has
so, whether the variations are transmitted to his offspring in accordance with
the laws whichprevail with the lower animals.
The evidence on which scientific accounts of human evolution is based comes
from many fields of natural science. The main sources of knowledge about the
evolutionary process has traditionally been the fossil record, but since the
development of genetics beginning in the 1970s, DNA analysis has come to
occupy a place of comparable importance. The studies of ontogeny, phylogeny
and especially evolutionary developmental biology of both vertebrates and
invertebrates offer considerable insight into the evolution of all life, including
how humans evolved.
6.1Evidence from comparative physiology
Many basic similarities in physiologic and chemical properties parallel the
morphologic features of organisms.
Many individual digestive enzymes present in different animals are essentially
alike in physiologic action. Trypsin, which acts upon proteins, occurs in many
animals right from protozoans to man, an amylase, which acts on starches, is
present from sponges to mammals.
Some hormones derived from endocrine glands show like reactions when
injected into different animals.The thyroid gland present in all vertebrates has
pg.12
been proved to be exchangeable among them.For example, the thyroid gland
in cattle controls their rate of metabolism;extracts of this gland has been
successfully used to feed human beings deficient in their own thyroid secretion
to speed up bodily metabolism. If beef or sheep thyroid is fed to frog tadpoles
from which the thyroid gland has been removed, the tadpoles will grow
normally and later metamorphose into frogs.This proves that all vertebrates
descended from a common ancestor.
6.2Evidence from comparative embryology
Every multicellularanimaloriginates from zygote or fertilized egg, except for a
few specialized types of reproduction. Theeggs of each species havea
distinctive ability to produce anindividual of that species, but there are many
features of embryonic development common to members of any anima group.
Fertilized eggs segment, pass through a blastula stage and a two-layered
gastrula stage, then become variously differentiated.
A study of the development of embryo of vertebrate groups by Von Baer
(1792-1876)revealed striking similarities occurring in all the groups
particularly during cleavage, gastulation and the early stages of differentiation.
Haeckel suggested that this had an evolutionary significance. He formulated
the principle of Biogenesis which states that ontogeny recapitulates phylogeny
that is during the development of an individual, it passes through many
been proved to be exchangeable among them.For example, the thyroid gland
in cattle controls their rate of metabolism;extracts of this gland has been
successfully used to feed human beings deficient in their own thyroid secretion
to speed up bodily metabolism. If beef or sheep thyroid is fed to frog tadpoles
from which the thyroid gland has been removed, the tadpoles will grow
normally and later metamorphose into frogs.This proves that all vertebrates
descended from a common ancestor.
6.2Evidence from comparative embryology
Every multicellularanimaloriginates from zygote or fertilized egg, except for a
few specialized types of reproduction. Theeggs of each species havea
distinctive ability to produce anindividual of that species, but there are many
features of embryonic development common to members of any anima group.
Fertilized eggs segment, pass through a blastula stage and a two-layered
gastrula stage, then become variously differentiated.
A study of the development of embryo of vertebrate groups by Von Baer
(1792-1876)revealed striking similarities occurring in all the groups
particularly during cleavage, gastulation and the early stages of differentiation.
Haeckel suggested that this had an evolutionary significance. He formulated
the principle of Biogenesis which states that ontogeny recapitulates phylogeny
that is during the development of an individual, it passes through many
pg.13
embryonic stages that its ancestor underwent because the mechanism of
development was inherited from a common ancestor.
In the development of human embryo, many primitive features appear and
disappear. The appearance of gill slits like those of fish, two chambered heart
like those of amphibians, possession of tail like thoseof reptiles and coat of
hair like those of monkeys, indicates that humans evolved through the fish,
amphibians, reptile and mammalian line.
The beginning embryo in a hen’s egg, has at first the vertebrate essentials of a
notochord, dorsal nervous system,and somites; later, it acquires bird features
such as beak and wings; and, much later, there appear the characteristics of a
chicken instead of a pigeon or duck.
The whalebone whales have no teeth in the adult stage but their embryos have
tooth buds whichare absorbed as development continues. Birds have no teeth
but their embryos have teeth buds. Thus the presence of the teeth buds in
whales and birds proves that they have descended from ancestors that had
teeth.
embryonic stages that its ancestor underwent because the mechanism of
development was inherited from a common ancestor.
In the development of human embryo, many primitive features appear and
disappear. The appearance of gill slits like those of fish, two chambered heart
like those of amphibians, possession of tail like thoseof reptiles and coat of
hair like those of monkeys, indicates that humans evolved through the fish,
amphibians, reptile and mammalian line.
The beginning embryo in a hen’s egg, has at first the vertebrate essentials of a
notochord, dorsal nervous system,and somites; later, it acquires bird features
such as beak and wings; and, much later, there appear the characteristics of a
chicken instead of a pigeon or duck.
The whalebone whales have no teeth in the adult stage but their embryos have
tooth buds whichare absorbed as development continues. Birds have no teeth
but their embryos have teeth buds. Thus the presence of the teeth buds in
whales and birds proves that they have descended from ancestors that had
teeth.
pg.14
Figure 1. Different stages in the development of three vertebrate animals.
Note their similarities in the very early stages and theirdifferences in theirstages.
pg.14
Figure 1. Different stages in the development of three vertebrate animals.
Note their similarities in the very early stages and theirdifferences in theirstages.
pg.14
Figure 1. Different stages in the development of three vertebrate animals.
Note their similarities in the very early stages and theirdifferences in theirstages.
Figure 1. Different stages in the development of three vertebrate animals.
Note their similarities in the very early stages and theirdifferences in theirstages.
pg.14
Figure 1. Different stages in the development of three vertebrate animals.
Note their similarities in the very early stages and theirdifferences in theirstages.
pg.14
Figure 1. Different stages in the development of three vertebrate animals.
Note their similarities in the very early stages and theirdifferences in theirstages.
pg.15
6.3Evidence from comparativeanatomy
The comparative study of the anatomy of groups reveals that certain structural
features arebasically similar. In examining animals for structural evidences of
evolution it is necessary to distinguish characters that are of common origin
(homology), hence indicative of common ancestry in descent, from purely
adaptive features that are of similarfunction (analogy) but of unlike origin.
Homologous structures can be used to explain the evidence of comparative
anatomy. Homologous structures are structure built in the same body plan but
modified to perform different functions. The forelimbs of frogs,whales, horse,
bird and man are in the pentadactyl plan but this basic structure have been
modified to perform different functions. Thus, the forelimb of frog is modified
for landing, that of bird modified as wing for flying, the horse forlimb has only
onefinger for fast running, that of whale is used for swimming while in man,
the forelimb could be rotated and has five fingers for holding and grasping.
Thesedifferent functions are brought about due to differences in the
environment. It can be explained therefore that the pentadactyl plan of the
forelimb of vertebrates indicate a genetic relationship and common ancestor.
6.3Evidence from comparativeanatomy
The comparative study of the anatomy of groups reveals that certain structural
features arebasically similar. In examining animals for structural evidences of
evolution it is necessary to distinguish characters that are of common origin
(homology), hence indicative of common ancestry in descent, from purely
adaptive features that are of similarfunction (analogy) but of unlike origin.
Homologous structures can be used to explain the evidence of comparative
anatomy. Homologous structures are structure built in the same body plan but
modified to perform different functions. The forelimbs of frogs,whales, horse,
bird and man are in the pentadactyl plan but this basic structure have been
modified to perform different functions. Thus, the forelimb of frog is modified
for landing, that of bird modified as wing for flying, the horse forlimb has only
onefinger for fast running, that of whale is used for swimming while in man,
the forelimb could be rotated and has five fingers for holding and grasping.
Thesedifferent functions are brought about due to differences in the
environment. It can be explained therefore that the pentadactyl plan of the
forelimb of vertebrates indicate a genetic relationship and common ancestor.
pg.16
Figure 2. The pentadactyl plan of forelimb of vertebrates.
6.4Evidence from vestigial organs
Vestigial organ is another convincingaspect of comparative anatomy. Vestigial
organs are homologous structures in some species that have no apparent
function, they are rudimentary or useless organs and of reduced size. From the
standpoint of special creation these are difficult to explain butfrom that of
evolution they are obviously features that were functional and necessary in
their ancestors but are now in process of disappearance from living organisms.
Inman,the appendix is a slender vestige about 2 ½ in. long that seems to have
pg.16
Figure 2. The pentadactyl plan of forelimb of vertebrates.
6.4Evidence from vestigial organs
Vestigial organ is another convincingaspect of comparative anatomy. Vestigial
organs are homologous structures in some species that have no apparent
function, they are rudimentary or useless organs and of reduced size. From the
standpoint of special creation these are difficult to explain butfrom that of
evolution they are obviously features that were functional and necessary in
their ancestors but are now in process of disappearance from living organisms.
Inman,the appendix is a slender vestige about 2 ½ in. long that seems to have
pg.16
Figure 2. The pentadactyl plan of forelimb of vertebrates.
6.4Evidence from vestigial organs
Vestigial organ is another convincingaspect of comparative anatomy. Vestigial
organs are homologous structures in some species that have no apparent
function, they are rudimentary or useless organs and of reduced size. From the
standpoint of special creation these are difficult to explain butfrom that of
evolution they are obviously features that were functional and necessary in
their ancestors but are now in process of disappearance from living organisms.
Inman,the appendix is a slender vestige about 2 ½ in. long that seems to have
Figure 2. The pentadactyl plan of forelimb of vertebrates.
6.4Evidence from vestigial organs
Vestigial organ is another convincingaspect of comparative anatomy. Vestigial
organs are homologous structures in some species that have no apparent
function, they are rudimentary or useless organs and of reduced size. From the
standpoint of special creation these are difficult to explain butfrom that of
evolution they are obviously features that were functional and necessary in
their ancestors but are now in process of disappearance from living organisms.
Inman,the appendix is a slender vestige about 2 ½ in. long that seems to have
pg.16
Figure 2. The pentadactyl plan of forelimb of vertebrates.
6.4Evidence from vestigial organs
Vestigial organ is another convincingaspect of comparative anatomy. Vestigial
organs are homologous structures in some species that have no apparent
function, they are rudimentary or useless organs and of reduced size. From the
standpoint of special creation these are difficult to explain butfrom that of
evolution they are obviously features that were functional and necessary in
their ancestors but are now in process of disappearance from living organisms.
Inman,the appendix is a slender vestige about 2 ½ in. long that seems to have
pg.16
Figure 2. The pentadactyl plan of forelimb of vertebrates.
6.4Evidence from vestigial organs
Vestigial organ is another convincingaspect of comparative anatomy. Vestigial
organs are homologous structures in some species that have no apparent
function, they are rudimentary or useless organs and of reduced size. From the
standpoint of special creation these are difficult to explain butfrom that of
evolution they are obviously features that were functional and necessary in
their ancestors but are now in process of disappearance from living organisms.
Inman,the appendix is a slender vestige about 2 ½ in. long that seems to have
pg.17
littlefunction and often is a site of infection requiring its surgical removal.
Although this organ is not concerned with digestion, is homologous with the
functional appendix of herbivorous mammals such as cow and goat.Another
example is the nonfunctional bones of snake and whale which are thought to be
homologous with the hip bones and hindlimbs of quadruped vertebrates.
Figure 3. Vestigial organ of man.
pg.17
littlefunction and often is a site of infection requiring its surgical removal.
Although this organ is not concerned with digestion, is homologous with the
functional appendix of herbivorous mammals such as cow and goat.Another
example is the nonfunctional bones of snake and whale which are thought to be
homologous with the hip bones and hindlimbs of quadruped vertebrates.
Figure 3. Vestigial organ of man.
pg.17
littlefunction and often is a site of infection requiring its surgical removal.
Although this organ is not concerned with digestion, is homologous with the
functional appendix of herbivorous mammals such as cow and goat.Another
example is the nonfunctional bones of snake and whale which are thought to be
homologous with the hip bones and hindlimbs of quadruped vertebrates.
Figure 3. Vestigial organ of man.
littlefunction and often is a site of infection requiring its surgical removal.
Although this organ is not concerned with digestion, is homologous with the
functional appendix of herbivorous mammals such as cow and goat.Another
example is the nonfunctional bones of snake and whale which are thought to be
homologous with the hip bones and hindlimbs of quadruped vertebrates.
Figure 3. Vestigial organ of man.
pg.17
littlefunction and often is a site of infection requiring its surgical removal.
Although this organ is not concerned with digestion, is homologous with the
functional appendix of herbivorous mammals such as cow and goat.Another
example is the nonfunctional bones of snake and whale which are thought to be
homologous with the hip bones and hindlimbs of quadruped vertebrates.
Figure 3. Vestigial organ of man.
pg.17
littlefunction and often is a site of infection requiring its surgical removal.
Although this organ is not concerned with digestion, is homologous with the
functional appendix of herbivorous mammals such as cow and goat.Another
example is the nonfunctional bones of snake and whale which are thought to be
homologous with the hip bones and hindlimbs of quadruped vertebrates.
Figure 3. Vestigial organ of man.
pg.18
6.5Genetics
Human evolutionary genetics studies how one human genome differs from the
other, theevolutionary past that gave rise to it, and its current effects.
Differences between genomes have anthropological, medical and forensic
implications and applications. Genetic data can provide important insight into
human evolution.
6.6Evidence from Molecular Biology
This indicates the molecular basis of life that has evolved early and has been
maintained with little variation across all life on the continent. The closest
living relatives of humans are bonobos and chimpanzees (both genusPan) and
gorillas (genusGorilla). With the sequencing of both the human and
chimpanzee genome, current estimates of the similarity between their DNA
sequences range between 95% and 99%. By using the technique called the
molecular clock which estimates the time required forthe number of divergent
mutations to accumulate between two lineages, the approximate date for the
split between lineages can be calculated. The gibbons (family Hylobatidae) and
orangutans (genusPongo) were the first groups to split from the line leadingto
the humans, then gorillas followed by the chimpanzees and bonobos. The
splitting date between human and chimpanzee lineages is placed around 4-8
million years ago during the late Miocene epoch.
6.5Genetics
Human evolutionary genetics studies how one human genome differs from the
other, theevolutionary past that gave rise to it, and its current effects.
Differences between genomes have anthropological, medical and forensic
implications and applications. Genetic data can provide important insight into
human evolution.
6.6Evidence from Molecular Biology
This indicates the molecular basis of life that has evolved early and has been
maintained with little variation across all life on the continent. The closest
living relatives of humans are bonobos and chimpanzees (both genusPan) and
gorillas (genusGorilla). With the sequencing of both the human and
chimpanzee genome, current estimates of the similarity between their DNA
sequences range between 95% and 99%. By using the technique called the
molecular clock which estimates the time required forthe number of divergent
mutations to accumulate between two lineages, the approximate date for the
split between lineages can be calculated. The gibbons (family Hylobatidae) and
orangutans (genusPongo) were the first groups to split from the line leadingto
the humans, then gorillas followed by the chimpanzees and bonobos. The
splitting date between human and chimpanzee lineages is placed around 4-8
million years ago during the late Miocene epoch.
pg.19
Genetic evidence has also been employed to resolve the question of whether
there was any gene flow between early modern humans and Neanderthals, and
to enhance our understanding of the early human migration patterns and
splitting dates. By comparing the parts of the genome that are not under natural
selection andwhich therefore accumulate mutations at a fairly steady rate, it is
possible to reconstruct a genetic tree incorporating the entire human species
since the last shared ancestor.
Each time a certain mutation (Single nucleotide polymorphism) appears in an
individual and is passed on to his or her descendant a haplogroup is formed
including all of the descendants of the individual who will also carry that
mutation. By comparing mitochondrial DNA which is inherited only from the
mother, geneticists have concluded that the last female common ancestor
whose genetic marker is found in all modern humans, the so-called
mitochondrial Eve, must have lived around 200,000 years ago.
6.7Evidence from the Fossil Record
Fossils serve to highlight the differences and similarities between the current
and extinct species showing the evolution of form over time. There is little
fossil evidence for the divergence of the gorilla, chimpanzee and hominin
lineages. The earliest fossils that have been proposed as members of the
hominin lineage areSahelanthropus tchadensisdating from 7 million years
Genetic evidence has also been employed to resolve the question of whether
there was any gene flow between early modern humans and Neanderthals, and
to enhance our understanding of the early human migration patterns and
splitting dates. By comparing the parts of the genome that are not under natural
selection andwhich therefore accumulate mutations at a fairly steady rate, it is
possible to reconstruct a genetic tree incorporating the entire human species
since the last shared ancestor.
Each time a certain mutation (Single nucleotide polymorphism) appears in an
individual and is passed on to his or her descendant a haplogroup is formed
including all of the descendants of the individual who will also carry that
mutation. By comparing mitochondrial DNA which is inherited only from the
mother, geneticists have concluded that the last female common ancestor
whose genetic marker is found in all modern humans, the so-called
mitochondrial Eve, must have lived around 200,000 years ago.
6.7Evidence from the Fossil Record
Fossils serve to highlight the differences and similarities between the current
and extinct species showing the evolution of form over time. There is little
fossil evidence for the divergence of the gorilla, chimpanzee and hominin
lineages. The earliest fossils that have been proposed as members of the
hominin lineage areSahelanthropus tchadensisdating from 7 million years
pg.20
ago,Orrorin tugenensisdating from 5.7 million years ago andArdipithecus
kadabbadating to 5.6 million years ago. Each of these has been argued to be a
bipedal ancestor of later hominins but, in each case, the claims have been
contested. It is also possible that one or more of these species are ancestors of
another branch of African apes, or that they represent a shared ancestor
between hominins and other apes.
From these early species, the australopithecines arose around 4 million years
ago and diverged into robust (also calledParanthropus) and gracile branches,
one of which (possiblyA. garhi) probably went on to become ancestors of the
genusHomo. The australopithecine species thatis best represented in the fossil
record isAustralopithecus afarensiswith more than one hundred fossil
individuals represented, found from Northern Ethiopia (such as the famous
"Lucy"), to Kenya, and South Africa. Fossils of robust australopithecines such
asA. robustus(or alternativelyParanthropus robustus) andA. /P. boiseiare
particularly abundant in South Africa at sites such as Kromdraai and
Swartkrans, and around Lake Turkana in Kenya.
The earliest members of the genusHomoareHomo habiliswhichevolved
around 2.3 million years ago.Homo habilisis the first species for which we
have positive evidence of the use of stone tools. They developed the oldowan
lithic technology, named after the Olduvai gorge in which the first specimens
ago,Orrorin tugenensisdating from 5.7 million years ago andArdipithecus
kadabbadating to 5.6 million years ago. Each of these has been argued to be a
bipedal ancestor of later hominins but, in each case, the claims have been
contested. It is also possible that one or more of these species are ancestors of
another branch of African apes, or that they represent a shared ancestor
between hominins and other apes.
From these early species, the australopithecines arose around 4 million years
ago and diverged into robust (also calledParanthropus) and gracile branches,
one of which (possiblyA. garhi) probably went on to become ancestors of the
genusHomo. The australopithecine species thatis best represented in the fossil
record isAustralopithecus afarensiswith more than one hundred fossil
individuals represented, found from Northern Ethiopia (such as the famous
"Lucy"), to Kenya, and South Africa. Fossils of robust australopithecines such
asA. robustus(or alternativelyParanthropus robustus) andA. /P. boiseiare
particularly abundant in South Africa at sites such as Kromdraai and
Swartkrans, and around Lake Turkana in Kenya.
The earliest members of the genusHomoareHomo habiliswhichevolved
around 2.3 million years ago.Homo habilisis the first species for which we
have positive evidence of the use of stone tools. They developed the oldowan
lithic technology, named after the Olduvai gorge in which the first specimens
pg.21
were found. Some scientists considerHomo rudolfensis, a larger bodied group
of fossils with similar morphology to the originalH. habilisfossils, to be a
separate species while others consider them to be part ofH. habilis-simply
representing species internal variation, or perhaps even sexual dimorphism.
The brains of these early hominins were about the same size as that of a
chimpanzee, and their main adaptation was bipedalism as an adaptation to
terrestrial living.
During the next million years, a process of encephalization began and, with the
arrival ofHomo erectusin the fossil record, cranial capacity had doubled.
Homo erectuswasthe first of the hominina to leave Africa, and this species
spread through Africa,Asia, and Europe between 1.3to1.8 million years ago.
One population ofH. erectus, also sometimes classified as a separate species
Homo ergaster, stayed in Africa and evolved intoHomo sapiens. It is believed
that these species were the first to use fireand complex tools.
The earliest transitional fossils betweenH. ergaster/erectusand ArchaicH.
sapiensare from Africa, such asHomo rhodesiensis, but seemingly transitional
forms were also found at Dmanisi, Georgia. These descendants of AfricanH.
erectusspread through Eurasia from ca. 500,000 years ago evolving intoH.
antecessor,H. heidelbergensisandH. neanderthalensis. The earliest fossils of
anatomically modern humans are from the Middle Paleolithic, about 200,000
were found. Some scientists considerHomo rudolfensis, a larger bodied group
of fossils with similar morphology to the originalH. habilisfossils, to be a
separate species while others consider them to be part ofH. habilis-simply
representing species internal variation, or perhaps even sexual dimorphism.
The brains of these early hominins were about the same size as that of a
chimpanzee, and their main adaptation was bipedalism as an adaptation to
terrestrial living.
During the next million years, a process of encephalization began and, with the
arrival ofHomo erectusin the fossil record, cranial capacity had doubled.
Homo erectuswasthe first of the hominina to leave Africa, and this species
spread through Africa,Asia, and Europe between 1.3to1.8 million years ago.
One population ofH. erectus, also sometimes classified as a separate species
Homo ergaster, stayed in Africa and evolved intoHomo sapiens. It is believed
that these species were the first to use fireand complex tools.
The earliest transitional fossils betweenH. ergaster/erectusand ArchaicH.
sapiensare from Africa, such asHomo rhodesiensis, but seemingly transitional
forms were also found at Dmanisi, Georgia. These descendants of AfricanH.
erectusspread through Eurasia from ca. 500,000 years ago evolving intoH.
antecessor,H. heidelbergensisandH. neanderthalensis. The earliest fossils of
anatomically modern humans are from the Middle Paleolithic, about 200,000
pg.22
years ago such as the Omo remains of Ethiopia; later fossils from Skhul in
Israel and Southern Europe begin around 90,000 years ago.
As modern humans spread out from Africa, they encountered other hominins
such asHomo neanderthalensisand the so-called Denisovans, who may have
evolved from populations ofHomo erectusthat had left Africa around 2
million years ago. The nature of interaction between early humans and these
sister species has been a long standing source of controversy, the question
being whether humans replaced these earlier species or whether they were in
fact similar enough to interbreed, in which case these earlier populations may
have contributed genetic material to modern humans.
Figure 4a:Replica of fossil skull ofHomo habilis. Figure 4b:Replica of fossil skull ofHomo ergaster
Fossil number KNM ER 1813, (AfricanHomo erectus).
Found at Koobi Fora, Kenya. Fossil number KHM HEU 3733,discovered in
Kenya, 1975.
pg.22
years ago such as the Omo remains of Ethiopia; later fossils from Skhul in
Israel and Southern Europe begin around 90,000 years ago.
As modern humans spread out from Africa, they encountered other hominins
such asHomo neanderthalensisand the so-called Denisovans, who may have
evolved from populations ofHomo erectusthat had left Africa around 2
million years ago. The nature of interaction between early humans and these
sister species has been a long standing source of controversy, the question
being whether humans replaced these earlier species or whether they were in
fact similar enough to interbreed, in which case these earlier populations may
have contributed genetic material to modern humans.
Figure 4a:Replica of fossil skull ofHomo habilis. Figure 4b:Replica of fossil skull ofHomo ergaster
Fossil number KNM ER 1813, (AfricanHomo erectus).
Found at Koobi Fora, Kenya. Fossil number KHM HEU 3733,discovered in
Kenya, 1975.
pg.22
years ago such as the Omo remains of Ethiopia; later fossils from Skhul in
Israel and Southern Europe begin around 90,000 years ago.
As modern humans spread out from Africa, they encountered other hominins
such asHomo neanderthalensisand the so-called Denisovans, who may have
evolved from populations ofHomo erectusthat had left Africa around 2
million years ago. The nature of interaction between early humans and these
sister species has been a long standing source of controversy, the question
being whether humans replaced these earlier species or whether they were in
fact similar enough to interbreed, in which case these earlier populations may
have contributed genetic material to modern humans.
Figure 4a:Replica of fossil skull ofHomo habilis. Figure 4b:Replica of fossil skull ofHomo ergaster
Fossil number KNM ER 1813, (AfricanHomo erectus).
Found at Koobi Fora, Kenya. Fossil number KHM HEU 3733,discovered in
Kenya, 1975.
years ago such as the Omo remains of Ethiopia; later fossils from Skhul in
Israel and Southern Europe begin around 90,000 years ago.
As modern humans spread out from Africa, they encountered other hominins
such asHomo neanderthalensisand the so-called Denisovans, who may have
evolved from populations ofHomo erectusthat had left Africa around 2
million years ago. The nature of interaction between early humans and these
sister species has been a long standing source of controversy, the question
being whether humans replaced these earlier species or whether they were in
fact similar enough to interbreed, in which case these earlier populations may
have contributed genetic material to modern humans.
Figure 4a:Replica of fossil skull ofHomo habilis. Figure 4b:Replica of fossil skull ofHomo ergaster
Fossil number KNM ER 1813, (AfricanHomo erectus).
Found at Koobi Fora, Kenya. Fossil number KHM HEU 3733,discovered in
Kenya, 1975.
pg.22
years ago such as the Omo remains of Ethiopia; later fossils from Skhul in
Israel and Southern Europe begin around 90,000 years ago.
As modern humans spread out from Africa, they encountered other hominins
such asHomo neanderthalensisand the so-called Denisovans, who may have
evolved from populations ofHomo erectusthat had left Africa around 2
million years ago. The nature of interaction between early humans and these
sister species has been a long standing source of controversy, the question
being whether humans replaced these earlier species or whether they were in
fact similar enough to interbreed, in which case these earlier populations may
have contributed genetic material to modern humans.
Figure 4a:Replica of fossil skull ofHomo habilis. Figure 4b:Replica of fossil skull ofHomo ergaster
Fossil number KNM ER 1813, (AfricanHomo erectus).
Found at Koobi Fora, Kenya. Fossil number KHM HEU 3733,discovered in
Kenya, 1975.
pg.22
years ago such as the Omo remains of Ethiopia; later fossils from Skhul in
Israel and Southern Europe begin around 90,000 years ago.
As modern humans spread out from Africa, they encountered other hominins
such asHomo neanderthalensisand the so-called Denisovans, who may have
evolved from populations ofHomo erectusthat had left Africa around 2
million years ago. The nature of interaction between early humans and these
sister species has been a long standing source of controversy, the question
being whether humans replaced these earlier species or whether they were in
fact similar enough to interbreed, in which case these earlier populations may
have contributed genetic material to modern humans.
Figure 4a:Replica of fossil skull ofHomo habilis. Figure 4b:Replica of fossil skull ofHomo ergaster
Fossil number KNM ER 1813, (AfricanHomo erectus).
Found at Koobi Fora, Kenya. Fossil number KHM HEU 3733,discovered in
Kenya, 1975.
pg.23
7.0DIVERGENCE OF THE HUMAN CLADE FROM OTHER
GREAT APES
Speciesclose to the last common ancestor of gorillas, chimpanzees and humans
may be represented byNakalipithecusfossils found in Kenya and
Ouranopithecusfound in Greece. Molecular evidence suggests that between 8
and 4 million years ago, first the gorillas, and then the chimpanzees (genus
Pan) split off from the line leading to the humans; human DNA is
approximately 98.4% identical to that of chimpanzees when comparing single
nucleotide polymorphisms. The fossil record of gorillas and chimpanzees is
limited. Both poor preservation (rain forest soils tend to be acidic and dissolve
bone) and sampling bias probably contribute to this problem.
Other hominins likely adapted to the drier environments outside the equatorial
belt, along with antelopes, hyenas, dogs, pigs, elephants, and horses. The
equatorial belt contracted after about 8 million years ago. There is very little
fossil evidence for the split of the hominin lineage from the lineages of gorillas
and chimpanzees. The earliest fossils that have been argued to belong to the
human lineage areSahelanthropus tchadensis(7million years ago) and
Orrorin tugenensis(6million years ago), followed byArdipithecus(5.5–4.4
million years ago), with speciesAr. kadabbaandAr. Ramidus.
7.0DIVERGENCE OF THE HUMAN CLADE FROM OTHER
GREAT APES
Speciesclose to the last common ancestor of gorillas, chimpanzees and humans
may be represented byNakalipithecusfossils found in Kenya and
Ouranopithecusfound in Greece. Molecular evidence suggests that between 8
and 4 million years ago, first the gorillas, and then the chimpanzees (genus
Pan) split off from the line leading to the humans; human DNA is
approximately 98.4% identical to that of chimpanzees when comparing single
nucleotide polymorphisms. The fossil record of gorillas and chimpanzees is
limited. Both poor preservation (rain forest soils tend to be acidic and dissolve
bone) and sampling bias probably contribute to this problem.
Other hominins likely adapted to the drier environments outside the equatorial
belt, along with antelopes, hyenas, dogs, pigs, elephants, and horses. The
equatorial belt contracted after about 8 million years ago. There is very little
fossil evidence for the split of the hominin lineage from the lineages of gorillas
and chimpanzees. The earliest fossils that have been argued to belong to the
human lineage areSahelanthropus tchadensis(7million years ago) and
Orrorin tugenensis(6million years ago), followed byArdipithecus(5.5–4.4
million years ago), with speciesAr. kadabbaandAr. Ramidus.
pg.24
Figure5:Family tree showing the extant hominoids: humans (genus Homo), chimpanzees
and bonobos (genusPan), gorillas (genusGorilla), orangutans (genusPongo), and gibbons
(four genera of the family Hylobatidae:Hylobates,Hoolock,Nomascus, andSymphalangus).
All except gibbons arehominids.
8.0ANATOMICAL CHANGES
Human evolution is characterized by a number of morphological,
developmental, physiological, and behavioral changes that have taken place
since the split between the last common ancestor of humansand chimpanzees.
The most significant of these adaptations are bipedalism, increased brain size,
lengthened ontogeny (gestation and infancy), and decreased sexual
dimorphism. The relationship between these changes is the subject of ongoing
debate. Other significant morphological changes included the evolution of a
power and precision grip, a change first occurring inH. erectus(Brues and
Snow 1965).
8.1Anatomy of Bipedalism
Bipedalism is not unique to humans; it is the basic adaption of theHomininline
and is considered themain cause behind a suite of skeletal changes shared by
pg.24
Figure5:Family tree showing the extant hominoids: humans (genus Homo), chimpanzees
and bonobos (genusPan), gorillas (genusGorilla), orangutans (genusPongo), and gibbons
(four genera of the family Hylobatidae:Hylobates,Hoolock,Nomascus, andSymphalangus).
All except gibbons arehominids.
8.0ANATOMICAL CHANGES
Human evolution is characterized by a number of morphological,
developmental, physiological, and behavioral changes that have taken place
since the split between the last common ancestor of humansand chimpanzees.
The most significant of these adaptations are bipedalism, increased brain size,
lengthened ontogeny (gestation and infancy), and decreased sexual
dimorphism. The relationship between these changes is the subject of ongoing
debate. Other significant morphological changes included the evolution of a
power and precision grip, a change first occurring inH. erectus(Brues and
Snow 1965).
8.1Anatomy of Bipedalism
Bipedalism is not unique to humans; it is the basic adaption of theHomininline
and is considered themain cause behind a suite of skeletal changes shared by
pg.24
Figure5:Family tree showing the extant hominoids: humans (genus Homo), chimpanzees
and bonobos (genusPan), gorillas (genusGorilla), orangutans (genusPongo), and gibbons
(four genera of the family Hylobatidae:Hylobates,Hoolock,Nomascus, andSymphalangus).
All except gibbons arehominids.
8.0ANATOMICAL CHANGES
Human evolution is characterized by a number of morphological,
developmental, physiological, and behavioral changes that have taken place
since the split between the last common ancestor of humansand chimpanzees.
The most significant of these adaptations are bipedalism, increased brain size,
lengthened ontogeny (gestation and infancy), and decreased sexual
dimorphism. The relationship between these changes is the subject of ongoing
debate. Other significant morphological changes included the evolution of a
power and precision grip, a change first occurring inH. erectus(Brues and
Snow 1965).
8.1Anatomy of Bipedalism
Bipedalism is not unique to humans; it is the basic adaption of theHomininline
and is considered themain cause behind a suite of skeletal changes shared by
Figure5:Family tree showing the extant hominoids: humans (genus Homo), chimpanzees
and bonobos (genusPan), gorillas (genusGorilla), orangutans (genusPongo), and gibbons
(four genera of the family Hylobatidae:Hylobates,Hoolock,Nomascus, andSymphalangus).
All except gibbons arehominids.
8.0ANATOMICAL CHANGES
Human evolution is characterized by a number of morphological,
developmental, physiological, and behavioral changes that have taken place
since the split between the last common ancestor of humansand chimpanzees.
The most significant of these adaptations are bipedalism, increased brain size,
lengthened ontogeny (gestation and infancy), and decreased sexual
dimorphism. The relationship between these changes is the subject of ongoing
debate. Other significant morphological changes included the evolution of a
power and precision grip, a change first occurring inH. erectus(Brues and
Snow 1965).
8.1Anatomy of Bipedalism
Bipedalism is not unique to humans; it is the basic adaption of theHomininline
and is considered themain cause behind a suite of skeletal changes shared by
pg.24
Figure5:Family tree showing the extant hominoids: humans (genus Homo), chimpanzees
and bonobos (genusPan), gorillas (genusGorilla), orangutans (genusPongo), and gibbons
(four genera of the family Hylobatidae:Hylobates,Hoolock,Nomascus, andSymphalangus).
All except gibbons arehominids.
8.0ANATOMICAL CHANGES
Human evolution is characterized by a number of morphological,
developmental, physiological, and behavioral changes that have taken place
since the split between the last common ancestor of humansand chimpanzees.
The most significant of these adaptations are bipedalism, increased brain size,
lengthened ontogeny (gestation and infancy), and decreased sexual
dimorphism. The relationship between these changes is the subject of ongoing
debate. Other significant morphological changes included the evolution of a
power and precision grip, a change first occurring inH. erectus(Brues and
Snow 1965).
8.1Anatomy of Bipedalism
Bipedalism is not unique to humans; it is the basic adaption of theHomininline
and is considered themain cause behind a suite of skeletal changes shared by
pg.24
Figure5:Family tree showing the extant hominoids: humans (genus Homo), chimpanzees
and bonobos (genusPan), gorillas (genusGorilla), orangutans (genusPongo), and gibbons
(four genera of the family Hylobatidae:Hylobates,Hoolock,Nomascus, andSymphalangus).
All except gibbons arehominids.
8.0ANATOMICAL CHANGES
Human evolution is characterized by a number of morphological,
developmental, physiological, and behavioral changes that have taken place
since the split between the last common ancestor of humansand chimpanzees.
The most significant of these adaptations are bipedalism, increased brain size,
lengthened ontogeny (gestation and infancy), and decreased sexual
dimorphism. The relationship between these changes is the subject of ongoing
debate. Other significant morphological changes included the evolution of a
power and precision grip, a change first occurring inH. erectus(Brues and
Snow 1965).
8.1Anatomy of Bipedalism
Bipedalism is not unique to humans; it is the basic adaption of theHomininline
and is considered themain cause behind a suite of skeletal changes shared by
pg.25
all bipedal hominins.Homo sapiensis the only mammal that is adapted
exclusively to bipedal striding. Accordingly, human bipedalism is a natural
development from the basicarboreal primate body plan, in which the hind
limbs are used to move about and sitting upright is common during feeding and
rest.
The initial changes toward an upright posture were probably related more to
standing, reaching, and squatting than to extended periods of walking and
running. Human beings stand with fully extended hip and knee joints, such that
the thighbones are aligned with their respective leg bones to form continuous
vertical columns(Lewin 1988). To walk, one simply tilts forward slightlyand
then keeps up with the displaced centre of mass, which is located within the
pelvis. The large muscle masses of the human lower limbs power our
locomotion and enable a person to rise from squatting and sitting postures.
Body mass is transferred throughthe pelvis, thighs, and legs to the heels, balls
of the feet, and toes. Remarkably little muscular effort is expended to stand in
place. Indeed, our large buttock, anterior thigh, and calf muscles are virtually
unused when we stand still. Instead of muscular contraction, the human bipedal
stance depends more on the way in which joints are constructed and on
strategically located ligaments that hold the joints in position. Fortunately for
paleoanthropologists, some bones show dramatic signs of how a given hominin
all bipedal hominins.Homo sapiensis the only mammal that is adapted
exclusively to bipedal striding. Accordingly, human bipedalism is a natural
development from the basicarboreal primate body plan, in which the hind
limbs are used to move about and sitting upright is common during feeding and
rest.
The initial changes toward an upright posture were probably related more to
standing, reaching, and squatting than to extended periods of walking and
running. Human beings stand with fully extended hip and knee joints, such that
the thighbones are aligned with their respective leg bones to form continuous
vertical columns(Lewin 1988). To walk, one simply tilts forward slightlyand
then keeps up with the displaced centre of mass, which is located within the
pelvis. The large muscle masses of the human lower limbs power our
locomotion and enable a person to rise from squatting and sitting postures.
Body mass is transferred throughthe pelvis, thighs, and legs to the heels, balls
of the feet, and toes. Remarkably little muscular effort is expended to stand in
place. Indeed, our large buttock, anterior thigh, and calf muscles are virtually
unused when we stand still. Instead of muscular contraction, the human bipedal
stance depends more on the way in which joints are constructed and on
strategically located ligaments that hold the joints in position. Fortunately for
paleoanthropologists, some bones show dramatic signs of how a given hominin
pg.26
carried itself and the adaptation to obligate terrestrial bipedalism led to notable
anatomic differences between hominins and great apes. These differences are
readily identified in fossils, particularly those of the pelvis and lower limbs.
Human feet are distinct from those of apes and monkeys. This is not surprising,
since in humans the feet must support and propel the entire body on their own
instead of sharing the load with the forelimbs. In humans the heel is very
robust, and the great toe is permanently aligned with the four diminutive lateral
toes. Unlike other primate feet, which have a mobile midfoot, the human foot
possesses (if not requires) a stable arch to give it strength. Accordingly, human
footprints are unique and are readily distinguished from those of other animals
(Srivastava 2009).
Figure 6.The hominoids are descendants of a common ancestor
pg.26
carried itself and the adaptation to obligate terrestrial bipedalism led to notable
anatomic differences between hominins and great apes. These differences are
readily identified in fossils, particularly those of the pelvis and lower limbs.
Human feet are distinct from those of apes and monkeys. This is not surprising,
since in humans the feet must support and propel the entire body on their own
instead of sharing the load with the forelimbs. In humans the heel is very
robust, and the great toe is permanently aligned with the four diminutive lateral
toes. Unlike other primate feet, which have a mobile midfoot, the human foot
possesses (if not requires) a stable arch to give it strength. Accordingly, human
footprints are unique and are readily distinguished from those of other animals
(Srivastava 2009).
Figure 6.The hominoids are descendants of a common ancestor
pg.26
carried itself and the adaptation to obligate terrestrial bipedalism led to notable
anatomic differences between hominins and great apes. These differences are
readily identified in fossils, particularly those of the pelvis and lower limbs.
Human feet are distinct from those of apes and monkeys. This is not surprising,
since in humans the feet must support and propel the entire body on their own
instead of sharing the load with the forelimbs. In humans the heel is very
robust, and the great toe is permanently aligned with the four diminutive lateral
toes. Unlike other primate feet, which have a mobile midfoot, the human foot
possesses (if not requires) a stable arch to give it strength. Accordingly, human
footprints are unique and are readily distinguished from those of other animals
(Srivastava 2009).
Figure 6.The hominoids are descendants of a common ancestor
carried itself and the adaptation to obligate terrestrial bipedalism led to notable
anatomic differences between hominins and great apes. These differences are
readily identified in fossils, particularly those of the pelvis and lower limbs.
Human feet are distinct from those of apes and monkeys. This is not surprising,
since in humans the feet must support and propel the entire body on their own
instead of sharing the load with the forelimbs. In humans the heel is very
robust, and the great toe is permanently aligned with the four diminutive lateral
toes. Unlike other primate feet, which have a mobile midfoot, the human foot
possesses (if not requires) a stable arch to give it strength. Accordingly, human
footprints are unique and are readily distinguished from those of other animals
(Srivastava 2009).
Figure 6.The hominoids are descendants of a common ancestor
pg.26
carried itself and the adaptation to obligate terrestrial bipedalism led to notable
anatomic differences between hominins and great apes. These differences are
readily identified in fossils, particularly those of the pelvis and lower limbs.
Human feet are distinct from those of apes and monkeys. This is not surprising,
since in humans the feet must support and propel the entire body on their own
instead of sharing the load with the forelimbs. In humans the heel is very
robust, and the great toe is permanently aligned with the four diminutive lateral
toes. Unlike other primate feet, which have a mobile midfoot, the human foot
possesses (if not requires) a stable arch to give it strength. Accordingly, human
footprints are unique and are readily distinguished from those of other animals
(Srivastava 2009).
Figure 6.The hominoids are descendants of a common ancestor
pg.26
carried itself and the adaptation to obligate terrestrial bipedalism led to notable
anatomic differences between hominins and great apes. These differences are
readily identified in fossils, particularly those of the pelvis and lower limbs.
Human feet are distinct from those of apes and monkeys. This is not surprising,
since in humans the feet must support and propel the entire body on their own
instead of sharing the load with the forelimbs. In humans the heel is very
robust, and the great toe is permanently aligned with the four diminutive lateral
toes. Unlike other primate feet, which have a mobile midfoot, the human foot
possesses (if not requires) a stable arch to give it strength. Accordingly, human
footprints are unique and are readily distinguished from those of other animals
(Srivastava 2009).
Figure 6.The hominoids are descendants of a common ancestor
pg.27
8.2Encephalization
The human species developed a much larger brain than that of other primates–
typically 1,330cm
3
in modern humans, over twice the size of that of a
chimpanzee or gorilla. The pattern of encephalization started withHomo
habilis, which at approximately 600cm
3
had a brain slightly larger than that of
chimpanzees, and continued withHomo erectus(800–1,100cm
3
), reaching a
maximum in Neanderthals with an average size of (1,200–1,900cm
3
), larger
even thanHomo sapiens. The pattern of human postnatal brain growth differs
from that of other apes (heterochrony) and allows for extended periods of
sociallearning and language acquisition in juvenile humans. However, the
differences between the structure of human brains and those of other apes may
be even more significant than differences in size. The increase in volume over
time has affected areas within the brain unequally–the temporal lobes, which
contain centers for language processing, have increased disproportionately, as
has the prefrontal cortex which has been related to complex decision-making
and moderating social behavior. Encephalization has been tied to an increasing
emphasis on meat in the diet, or with the development of cooking, and it has
been proposed that intelligence increased as a response to an increased
necessity for solving social problems as human society became more complex.
8.2Encephalization
The human species developed a much larger brain than that of other primates–
typically 1,330cm
3
in modern humans, over twice the size of that of a
chimpanzee or gorilla. The pattern of encephalization started withHomo
habilis, which at approximately 600cm
3
had a brain slightly larger than that of
chimpanzees, and continued withHomo erectus(800–1,100cm
3
), reaching a
maximum in Neanderthals with an average size of (1,200–1,900cm
3
), larger
even thanHomo sapiens. The pattern of human postnatal brain growth differs
from that of other apes (heterochrony) and allows for extended periods of
sociallearning and language acquisition in juvenile humans. However, the
differences between the structure of human brains and those of other apes may
be even more significant than differences in size. The increase in volume over
time has affected areas within the brain unequally–the temporal lobes, which
contain centers for language processing, have increased disproportionately, as
has the prefrontal cortex which has been related to complex decision-making
and moderating social behavior. Encephalization has been tied to an increasing
emphasis on meat in the diet, or with the development of cooking, and it has
been proposed that intelligence increased as a response to an increased
necessity for solving social problems as human society became more complex.
pg.28
Figure 7.Craniums–1.Gorilla,2.Australopithecus, 3.Homo erectus, 4. Neanderthal, 5.
Steinheim Skull, 6. Euhominid.
8.3Sexual Dimorphism
The reduced degree of sexual dimorphism is visible primarily in the reduction
of the male canine tooth relativeto other ape species (except gibbons) and
reduced brow ridges and general robustness of males. Another important
physiological change related to sexuality in humans was the evolution of
hidden estrus. Humans and bonobos are the only apes in which the female is
fertile year round and in which no special signals of fertility are produced by
the body (such as genital swelling during estrus).
Nonetheless, humans retain a degree of sexual dimorphism in the distribution
of body hair and subcutaneous fat, and in the overall size, males being around
pg.28
Figure 7.Craniums–1.Gorilla,2.Australopithecus, 3.Homo erectus, 4. Neanderthal, 5.
Steinheim Skull, 6. Euhominid.
8.3Sexual Dimorphism
The reduced degree of sexual dimorphism is visible primarily in the reduction
of the male canine tooth relativeto other ape species (except gibbons) and
reduced brow ridges and general robustness of males. Another important
physiological change related to sexuality in humans was the evolution of
hidden estrus. Humans and bonobos are the only apes in which the female is
fertile year round and in which no special signals of fertility are produced by
the body (such as genital swelling during estrus).
Nonetheless, humans retain a degree of sexual dimorphism in the distribution
of body hair and subcutaneous fat, and in the overall size, males being around
pg.28
Figure 7.Craniums–1.Gorilla,2.Australopithecus, 3.Homo erectus, 4. Neanderthal, 5.
Steinheim Skull, 6. Euhominid.
8.3Sexual Dimorphism
The reduced degree of sexual dimorphism is visible primarily in the reduction
of the male canine tooth relativeto other ape species (except gibbons) and
reduced brow ridges and general robustness of males. Another important
physiological change related to sexuality in humans was the evolution of
hidden estrus. Humans and bonobos are the only apes in which the female is
fertile year round and in which no special signals of fertility are produced by
the body (such as genital swelling during estrus).
Nonetheless, humans retain a degree of sexual dimorphism in the distribution
of body hair and subcutaneous fat, and in the overall size, males being around
Figure 7.Craniums–1.Gorilla,2.Australopithecus, 3.Homo erectus, 4. Neanderthal, 5.
Steinheim Skull, 6. Euhominid.
8.3Sexual Dimorphism
The reduced degree of sexual dimorphism is visible primarily in the reduction
of the male canine tooth relativeto other ape species (except gibbons) and
reduced brow ridges and general robustness of males. Another important
physiological change related to sexuality in humans was the evolution of
hidden estrus. Humans and bonobos are the only apes in which the female is
fertile year round and in which no special signals of fertility are produced by
the body (such as genital swelling during estrus).
Nonetheless, humans retain a degree of sexual dimorphism in the distribution
of body hair and subcutaneous fat, and in the overall size, males being around
pg.28
Figure 7.Craniums–1.Gorilla,2.Australopithecus, 3.Homo erectus, 4. Neanderthal, 5.
Steinheim Skull, 6. Euhominid.
8.3Sexual Dimorphism
The reduced degree of sexual dimorphism is visible primarily in the reduction
of the male canine tooth relativeto other ape species (except gibbons) and
reduced brow ridges and general robustness of males. Another important
physiological change related to sexuality in humans was the evolution of
hidden estrus. Humans and bonobos are the only apes in which the female is
fertile year round and in which no special signals of fertility are produced by
the body (such as genital swelling during estrus).
Nonetheless, humans retain a degree of sexual dimorphism in the distribution
of body hair and subcutaneous fat, and in the overall size, males being around
pg.28
Figure 7.Craniums–1.Gorilla,2.Australopithecus, 3.Homo erectus, 4. Neanderthal, 5.
Steinheim Skull, 6. Euhominid.
8.3Sexual Dimorphism
The reduced degree of sexual dimorphism is visible primarily in the reduction
of the male canine tooth relativeto other ape species (except gibbons) and
reduced brow ridges and general robustness of males. Another important
physiological change related to sexuality in humans was the evolution of
hidden estrus. Humans and bonobos are the only apes in which the female is
fertile year round and in which no special signals of fertility are produced by
the body (such as genital swelling during estrus).
Nonetheless, humans retain a degree of sexual dimorphism in the distribution
of body hair and subcutaneous fat, and in the overall size, males being around
pg.29
15% larger than females. These changes taken together have been interpreted
as a result of an increased emphasis on pair bonding as a possible solution to
the requirement for increased parental investment due to the prolonged infancy
of offspring.
Other Changes
A number of other changes have also characterized the evolution of humans,
among them an increased importance on vision rather than smell; a smaller gut;
loss of body hair; evolution of sweat glands; a change in the shape of the dental
arcade from being u-shaped to being parabolic; development of a chin (found
inHomo sapiensalone), development of styloid processes; development of a
descended larynx.
9.0GENUS HOMO
The wordhomo, the name of the biological genus to which humans belong, is
Latin for "human". It was chosen originally by Carolus Linnaeus in his
classification system. The word "human" is from the Latinhumanus, the
adjectival form ofhomo. Linnaeus and other scientists of his time also
considered the great apes to be the closest relatives of humans based on
morphological and anatomical similarities.
15% larger than females. These changes taken together have been interpreted
as a result of an increased emphasis on pair bonding as a possible solution to
the requirement for increased parental investment due to the prolonged infancy
of offspring.
Other Changes
A number of other changes have also characterized the evolution of humans,
among them an increased importance on vision rather than smell; a smaller gut;
loss of body hair; evolution of sweat glands; a change in the shape of the dental
arcade from being u-shaped to being parabolic; development of a chin (found
inHomo sapiensalone), development of styloid processes; development of a
descended larynx.
9.0GENUS HOMO
The wordhomo, the name of the biological genus to which humans belong, is
Latin for "human". It was chosen originally by Carolus Linnaeus in his
classification system. The word "human" is from the Latinhumanus, the
adjectival form ofhomo. Linnaeus and other scientists of his time also
considered the great apes to be the closest relatives of humans based on
morphological and anatomical similarities.
pg.30
Homo sapiensis the only old and still existing species of its genus,Homo.
While some other, extinctHomospecies might have been ancestors ofHomo
sapiens, many were likely our "cousins", having separated away from our
ancestral line (Straitet al.1997). There is not yet a consensus as to which of
these groups should count as separate species and which as subspecies. In some
cases this is due to the dearth of fossils, in other cases it is due to the slight
differences used to classify species in theHomogenus (Bill 2004). The Sahara
pump theory (describing an occasionally passable "wet" Sahara Desert)
provides one possible explanation of the early variation in the genusHomo.
Based on archaeological and paleontological evidence, it has been possible to
infer, to some extent, the ancient dietary practices of variousHomospecies and
to study the role of dietin physical and behavioral evolution withinHomo.
H. habilis and H. gautengensis
Homo habilislived from about 2.4 to 1.4million years ago.Homo habilis
evolved in South and East Africa in the late Pliocene or early Pleistocene, 2.5–
2million years ago, when it diverged from the australopithecines.Homo
habilishad smaller molars and larger brains than the australopithecines, and
made tools from stone and perhaps animal bones. One of the first known
hominids, it was nicknamed'handy man'by discoverer Louis Leakey due to
its association with stone tools. Some scientists have proposed moving this
Homo sapiensis the only old and still existing species of its genus,Homo.
While some other, extinctHomospecies might have been ancestors ofHomo
sapiens, many were likely our "cousins", having separated away from our
ancestral line (Straitet al.1997). There is not yet a consensus as to which of
these groups should count as separate species and which as subspecies. In some
cases this is due to the dearth of fossils, in other cases it is due to the slight
differences used to classify species in theHomogenus (Bill 2004). The Sahara
pump theory (describing an occasionally passable "wet" Sahara Desert)
provides one possible explanation of the early variation in the genusHomo.
Based on archaeological and paleontological evidence, it has been possible to
infer, to some extent, the ancient dietary practices of variousHomospecies and
to study the role of dietin physical and behavioral evolution withinHomo.
H. habilis and H. gautengensis
Homo habilislived from about 2.4 to 1.4million years ago.Homo habilis
evolved in South and East Africa in the late Pliocene or early Pleistocene, 2.5–
2million years ago, when it diverged from the australopithecines.Homo
habilishad smaller molars and larger brains than the australopithecines, and
made tools from stone and perhaps animal bones. One of the first known
hominids, it was nicknamed'handy man'by discoverer Louis Leakey due to
its association with stone tools. Some scientists have proposed moving this
pg.31
species out ofHomoand intoAustralopithecusdue to the morphology of its
skeleton being more adapted to living on trees rather than to moving on two
legs likeHomo sapiens(Wood andCollard1999).
It was considered to be the first species of the genusHomountil May 2010,
when a new species,Homogautengensiswas discovered in SouthAfrica that
most likely arose earlier thanHomo habilis.
Figure8.A reconstruction of Homo habilis
H. rudolfensis and H. georgicus
These are proposed species names for fossils from about 1.9–1.6million years
ago, whose relation toHomo habilisis not yet clear.
Homo rudolfensisrefers to a single, incomplete skull fromKenya.
Scientists have suggested that this was anotherHomo habilis, but this
has not been confirmed.
pg.31
species out ofHomoand intoAustralopithecusdue to the morphology of its
skeleton being more adapted to living on trees rather than to moving on two
legs likeHomo sapiens(Wood andCollard1999).
It was considered to be the first species of the genusHomountil May 2010,
when a new species,Homogautengensiswas discovered in SouthAfrica that
most likely arose earlier thanHomo habilis.
Figure8.A reconstruction of Homo habilis
H. rudolfensis and H. georgicus
These are proposed species names for fossils from about 1.9–1.6million years
ago, whose relation toHomo habilisis not yet clear.
Homo rudolfensisrefers to a single, incomplete skull fromKenya.
Scientists have suggested that this was anotherHomo habilis, but this
has not been confirmed.
pg.31
species out ofHomoand intoAustralopithecusdue to the morphology of its
skeleton being more adapted to living on trees rather than to moving on two
legs likeHomo sapiens(Wood andCollard1999).
It was considered to be the first species of the genusHomountil May 2010,
when a new species,Homogautengensiswas discovered in SouthAfrica that
most likely arose earlier thanHomo habilis.
Figure8.A reconstruction of Homo habilis
H. rudolfensis and H. georgicus
These are proposed species names for fossils from about 1.9–1.6million years
ago, whose relation toHomo habilisis not yet clear.
Homo rudolfensisrefers to a single, incomplete skull fromKenya.
Scientists have suggested that this was anotherHomo habilis, but this
has not been confirmed.
species out ofHomoand intoAustralopithecusdue to the morphology of its
skeleton being more adapted to living on trees rather than to moving on two
legs likeHomo sapiens(Wood andCollard1999).
It was considered to be the first species of the genusHomountil May 2010,
when a new species,Homogautengensiswas discovered in SouthAfrica that
most likely arose earlier thanHomo habilis.
Figure8.A reconstruction of Homo habilis
H. rudolfensis and H. georgicus
These are proposed species names for fossils from about 1.9–1.6million years
ago, whose relation toHomo habilisis not yet clear.
Homo rudolfensisrefers to a single, incomplete skull fromKenya.
Scientists have suggested that this was anotherHomo habilis, but this
has not been confirmed.
pg.31
species out ofHomoand intoAustralopithecusdue to the morphology of its
skeleton being more adapted to living on trees rather than to moving on two
legs likeHomo sapiens(Wood andCollard1999).
It was considered to be the first species of the genusHomountil May 2010,
when a new species,Homogautengensiswas discovered in SouthAfrica that
most likely arose earlier thanHomo habilis.
Figure8.A reconstruction of Homo habilis
H. rudolfensis and H. georgicus
These are proposed species names for fossils from about 1.9–1.6million years
ago, whose relation toHomo habilisis not yet clear.
Homo rudolfensisrefers to a single, incomplete skull fromKenya.
Scientists have suggested that this was anotherHomo habilis, but this
has not been confirmed.
pg.31
species out ofHomoand intoAustralopithecusdue to the morphology of its
skeleton being more adapted to living on trees rather than to moving on two
legs likeHomo sapiens(Wood andCollard1999).
It was considered to be the first species of the genusHomountil May 2010,
when a new species,Homogautengensiswas discovered in SouthAfrica that
most likely arose earlier thanHomo habilis.
Figure8.A reconstruction of Homo habilis
H. rudolfensis and H. georgicus
These are proposed species names for fossils from about 1.9–1.6million years
ago, whose relation toHomo habilisis not yet clear.
Homo rudolfensisrefers to a single, incomplete skull fromKenya.
Scientists have suggested that this was anotherHomo habilis, but this
has not been confirmed.
pg.32
Homo georgicus, from Georgia, may be an intermediate form between
Homo habilisandHomo erectus, or a sub-species ofHomo erectus.
H. ergaster and H. erectus
The first fossils ofHomo erectuswere discovered by Dutch physician Eugene
Dubois in 1891 on the Indonesian island of Java. He originally named the
materialPithecanthropus erectusbased on its morphology, which he
considered to be intermediate between that of humans and apes.Homo erectus
(H. erectus) lived from about 1.8million years agoto about 70,000 years ago
(which would indicate that they were probably wiped out by the Toba
catastrophe; however,Homo erectus soloensisandHomo floresiensissurvived
it). Often the early phase, from 1.8 to 1.25million years ago, is considered to
be a separate species,Homo ergaster, or it is seen as a subspecies ofHomo
erectus,Homo erectus ergaster.
In the early Pleistocene, 1.5–1million years ago, in Africa some populations of
Homo habilisare thought to have evolved larger brains and made more
elaborate stone tools; these differences and others are sufficient for
anthropologists to classify them as a new species,Homo erectus(Spooret al.
1994). This was made possible by the evolution of locking knees and a
Homo georgicus, from Georgia, may be an intermediate form between
Homo habilisandHomo erectus, or a sub-species ofHomo erectus.
H. ergaster and H. erectus
The first fossils ofHomo erectuswere discovered by Dutch physician Eugene
Dubois in 1891 on the Indonesian island of Java. He originally named the
materialPithecanthropus erectusbased on its morphology, which he
considered to be intermediate between that of humans and apes.Homo erectus
(H. erectus) lived from about 1.8million years agoto about 70,000 years ago
(which would indicate that they were probably wiped out by the Toba
catastrophe; however,Homo erectus soloensisandHomo floresiensissurvived
it). Often the early phase, from 1.8 to 1.25million years ago, is considered to
be a separate species,Homo ergaster, or it is seen as a subspecies ofHomo
erectus,Homo erectus ergaster.
In the early Pleistocene, 1.5–1million years ago, in Africa some populations of
Homo habilisare thought to have evolved larger brains and made more
elaborate stone tools; these differences and others are sufficient for
anthropologists to classify them as a new species,Homo erectus(Spooret al.
1994). This was made possible by the evolution of locking knees and a
pg.33
different location of the foramen magnum (the hole in the skull where the spine
enters). They may have used fire to cook their meat.
A famous example ofHomo erectusis Peking Man; others were found in Asia
(notably in Indonesia), Africa, and Europe. Many paleoanthropologists now
use the termHomo ergasterfor the non-Asian forms of this group, and reserve
Homo erectusonly for those fossils that are found in Asia and meet certain
skeletal and dental requirements which differ slightly fromH. ergaster.
H. cepranensis and H. antecessor
These are proposed as species that may be intermediate betweenH. erectusand
H. heidelbergensis.
H. antecessoris known from fossils from Spainand England that are
dated1.2 million years ago–500thousand yearsago.
H. cepranensisrefers to a single skull cap from Italy, estimated to be
about 800,000 years old.
H. heidelbergensis
H. heidelbergensis(Heidelberg Man) lived from about 800,000 to about
300,000 years ago. Also proposed asHomo sapiens heidelbergensisorHomo
sapiens paleohungaricus.
different location of the foramen magnum (the hole in the skull where the spine
enters). They may have used fire to cook their meat.
A famous example ofHomo erectusis Peking Man; others were found in Asia
(notably in Indonesia), Africa, and Europe. Many paleoanthropologists now
use the termHomo ergasterfor the non-Asian forms of this group, and reserve
Homo erectusonly for those fossils that are found in Asia and meet certain
skeletal and dental requirements which differ slightly fromH. ergaster.
H. cepranensis and H. antecessor
These are proposed as species that may be intermediate betweenH. erectusand
H. heidelbergensis.
H. antecessoris known from fossils from Spainand England that are
dated1.2 million years ago–500thousand yearsago.
H. cepranensisrefers to a single skull cap from Italy, estimated to be
about 800,000 years old.
H. heidelbergensis
H. heidelbergensis(Heidelberg Man) lived from about 800,000 to about
300,000 years ago. Also proposed asHomo sapiens heidelbergensisorHomo
sapiens paleohungaricus.
pg.34
Figure9:Reconstruction ofHomo heidelbergensis
The direct ancestor of bothHomo neanderthalensisandHomo sapiens
H. rhodesiensis, and the Gawis cranium
H. rhodesiensis, estimated to be 300,000–125,000 years old. Most
current researchers place Rhodesian Man within the group ofHomo
heidelbergensis, though other designations such as ArchaicHomo
sapiensandHomo sapiens rhodesiensishave been proposed.
In February 2006 a fossil, the Gawis cranium, was found which might
possibly be a species intermediate betweenH. erectusandH. sapiensor
one of many evolutionary dead ends. The skull from Gawis, Ethiopia, is
believed to be 500,000–250,000 years old. Only summary details are
known, and the finders have not yet released a peer-reviewed study.
Gawis man's facial features suggest its being either an intermediate
species or an example of a "Bodo man" female.
Neanderthal and Denisova hominin
pg.34
Figure9:Reconstruction ofHomo heidelbergensis
The direct ancestor of bothHomo neanderthalensisandHomo sapiens
H. rhodesiensis, and the Gawis cranium
H. rhodesiensis, estimated to be 300,000–125,000 years old. Most
current researchers place Rhodesian Man within the group ofHomo
heidelbergensis, though other designations such as ArchaicHomo
sapiensandHomo sapiens rhodesiensishave been proposed.
In February 2006 a fossil, the Gawis cranium, was found which might
possibly be a species intermediate betweenH. erectusandH. sapiensor
one of many evolutionary dead ends. The skull from Gawis, Ethiopia, is
believed to be 500,000–250,000 years old. Only summary details are
known, and the finders have not yet released a peer-reviewed study.
Gawis man's facial features suggest its being either an intermediate
species or an example of a "Bodo man" female.
Neanderthal and Denisova hominin
pg.34
Figure9:Reconstruction ofHomo heidelbergensis
The direct ancestor of bothHomo neanderthalensisandHomo sapiens
H. rhodesiensis, and the Gawis cranium
H. rhodesiensis, estimated to be 300,000–125,000 years old. Most
current researchers place Rhodesian Man within the group ofHomo
heidelbergensis, though other designations such as ArchaicHomo
sapiensandHomo sapiens rhodesiensishave been proposed.
In February 2006 a fossil, the Gawis cranium, was found which might
possibly be a species intermediate betweenH. erectusandH. sapiensor
one of many evolutionary dead ends. The skull from Gawis, Ethiopia, is
believed to be 500,000–250,000 years old. Only summary details are
known, and the finders have not yet released a peer-reviewed study.
Gawis man's facial features suggest its being either an intermediate
species or an example of a "Bodo man" female.
Neanderthal and Denisova hominin
Figure9:Reconstruction ofHomo heidelbergensis
The direct ancestor of bothHomo neanderthalensisandHomo sapiens
H. rhodesiensis, and the Gawis cranium
H. rhodesiensis, estimated to be 300,000–125,000 years old. Most
current researchers place Rhodesian Man within the group ofHomo
heidelbergensis, though other designations such as ArchaicHomo
sapiensandHomo sapiens rhodesiensishave been proposed.
In February 2006 a fossil, the Gawis cranium, was found which might
possibly be a species intermediate betweenH. erectusandH. sapiensor
one of many evolutionary dead ends. The skull from Gawis, Ethiopia, is
believed to be 500,000–250,000 years old. Only summary details are
known, and the finders have not yet released a peer-reviewed study.
Gawis man's facial features suggest its being either an intermediate
species or an example of a "Bodo man" female.
Neanderthal and Denisova hominin
pg.34
Figure9:Reconstruction ofHomo heidelbergensis
The direct ancestor of bothHomo neanderthalensisandHomo sapiens
H. rhodesiensis, and the Gawis cranium
H. rhodesiensis, estimated to be 300,000–125,000 years old. Most
current researchers place Rhodesian Man within the group ofHomo
heidelbergensis, though other designations such as ArchaicHomo
sapiensandHomo sapiens rhodesiensishave been proposed.
In February 2006 a fossil, the Gawis cranium, was found which might
possibly be a species intermediate betweenH. erectusandH. sapiensor
one of many evolutionary dead ends. The skull from Gawis, Ethiopia, is
believed to be 500,000–250,000 years old. Only summary details are
known, and the finders have not yet released a peer-reviewed study.
Gawis man's facial features suggest its being either an intermediate
species or an example of a "Bodo man" female.
Neanderthal and Denisova hominin
pg.34
Figure9:Reconstruction ofHomo heidelbergensis
The direct ancestor of bothHomo neanderthalensisandHomo sapiens
H. rhodesiensis, and the Gawis cranium
H. rhodesiensis, estimated to be 300,000–125,000 years old. Most
current researchers place Rhodesian Man within the group ofHomo
heidelbergensis, though other designations such as ArchaicHomo
sapiensandHomo sapiens rhodesiensishave been proposed.
In February 2006 a fossil, the Gawis cranium, was found which might
possibly be a species intermediate betweenH. erectusandH. sapiensor
one of many evolutionary dead ends. The skull from Gawis, Ethiopia, is
believed to be 500,000–250,000 years old. Only summary details are
known, and the finders have not yet released a peer-reviewed study.
Gawis man's facial features suggest its being either an intermediate
species or an example of a "Bodo man" female.
Neanderthal and Denisova hominin
pg.35
Harvati (2003) alternatively designatedH. neanderthalensisasHomo sapiens
neanderthalensis. They lived in Europe and Asia from 400,000 to about 30,000
years ago (Herrera,et al.2009). Evidence from sequencing mitochondrial
DNA indicated that no significant gene flow occurred betweenH.
neanderthalensisandH. sapiens, and, therefore, the two were separate species
that shared a common ancestor about 660,000 years ago (Kringset al.1997).
However, the 2010 sequencing of the Neanderthal genome indicated that
Neanderthals did indeed interbreed with anatomically modern humanscirca
45,000 to 80,000 years ago (at the approximate time that modern humans
migrated out from Africa, but before they dispersed into Europe, Asia and
elsewhere).
Nearly all modernnon-African humans have 1% to 4% of their DNA derived
from Neanderthal DNA,and this finding is consistent with recent studies
indicating that the divergence of some human allelesdates to one million years
ago, although the interpretation of these studieshas been questioned
(Hebsgaardet al.2007).Competition fromHomo sapiensprobably contributed
to Neanderthal extinction. They could have co-existed in Europe for as long as
10,000 years, during which human populations exploded vastly outnumbering
Neanderthals, possibly outcompeting them by sheer numerical strength
(Mellarset al.2011).
Harvati (2003) alternatively designatedH. neanderthalensisasHomo sapiens
neanderthalensis. They lived in Europe and Asia from 400,000 to about 30,000
years ago (Herrera,et al.2009). Evidence from sequencing mitochondrial
DNA indicated that no significant gene flow occurred betweenH.
neanderthalensisandH. sapiens, and, therefore, the two were separate species
that shared a common ancestor about 660,000 years ago (Kringset al.1997).
However, the 2010 sequencing of the Neanderthal genome indicated that
Neanderthals did indeed interbreed with anatomically modern humanscirca
45,000 to 80,000 years ago (at the approximate time that modern humans
migrated out from Africa, but before they dispersed into Europe, Asia and
elsewhere).
Nearly all modernnon-African humans have 1% to 4% of their DNA derived
from Neanderthal DNA,and this finding is consistent with recent studies
indicating that the divergence of some human allelesdates to one million years
ago, although the interpretation of these studieshas been questioned
(Hebsgaardet al.2007).Competition fromHomo sapiensprobably contributed
to Neanderthal extinction. They could have co-existed in Europe for as long as
10,000 years, during which human populations exploded vastly outnumbering
Neanderthals, possibly outcompeting them by sheer numerical strength
(Mellarset al.2011).
pg.36
In 2008, archaeologists working at the site of Denisova Cave in the Altai
Mountains of Siberia uncovered a small bone fragment from the fifth finger of
a juvenile memberof a population now referred to as Denisova hominins, or
simply Denisovans(Brown 2010).Artifacts, including a bracelet, excavated in
the cave at the same level were carbon dated to around 40,000 BP. As DNA
had survived in the fossil fragment due to the cool climate of the Denisova
Cave, both mtDNA and nuclear genomic DNA were sequenced.
While the divergence point of the mtDNA was unexpectedly deep in time, the
full genomic sequence suggested the Denisovans belonged to the same lineage
as Neanderthals, with the two diverging shortly after their line split from that
lineage giving rise to modern humans(Reichet al.2010). Modern humans are
known to have overlapped with Neanderthals in Europe for more than 10,000
years, and the discovery raises the possibility that Neanderthals, modern
humans and the Denisova hominin may have co-existed. The existence of this
distant branch creates a much more complex picture of humankind during the
Late Pleistocene than previously thought(Bokmaet al. 2012). Evidence has
also been found that as much as 6% of the genomes of some modern
Melanesians derive from Denisovans, indicating limited interbreeding in
SoutheastAsia.
In 2008, archaeologists working at the site of Denisova Cave in the Altai
Mountains of Siberia uncovered a small bone fragment from the fifth finger of
a juvenile memberof a population now referred to as Denisova hominins, or
simply Denisovans(Brown 2010).Artifacts, including a bracelet, excavated in
the cave at the same level were carbon dated to around 40,000 BP. As DNA
had survived in the fossil fragment due to the cool climate of the Denisova
Cave, both mtDNA and nuclear genomic DNA were sequenced.
While the divergence point of the mtDNA was unexpectedly deep in time, the
full genomic sequence suggested the Denisovans belonged to the same lineage
as Neanderthals, with the two diverging shortly after their line split from that
lineage giving rise to modern humans(Reichet al.2010). Modern humans are
known to have overlapped with Neanderthals in Europe for more than 10,000
years, and the discovery raises the possibility that Neanderthals, modern
humans and the Denisova hominin may have co-existed. The existence of this
distant branch creates a much more complex picture of humankind during the
Late Pleistocene than previously thought(Bokmaet al. 2012). Evidence has
also been found that as much as 6% of the genomes of some modern
Melanesians derive from Denisovans, indicating limited interbreeding in
SoutheastAsia.
pg.37
Alleles thought to have originated in Neanderthal and the Denisova hominin
have been identified at several genetic loci in the genomes of modern humans
outside of Africa. HLA types from Denisovans and Neanderthal represent more
than half the HLA alleles ofmodern Eurasians, indicating strong positive
selection for these introgressed alleles.
Figure10:Dermoplastic reconstruction of a Neanderthal
H. floresiensis
H. floresiensis, which lived from approximately 100,000 to 12,000 before
present, has been nicknamedhobbitfor its small size, possibly a result of
insular dwarfism(Brownet al.2004).H. floresiensisis intriguing both for its
size and its age, being an example of a recent species of the genusHomothat
exhibits derived traits not shared with modern humans. In other words,H.
floresiensisshares a common ancestor with modern humans, but split from the
modern human lineage and followed a distinct evolutionary path. Themain
pg.37
Alleles thought to have originated in Neanderthal and the Denisova hominin
have been identified at several genetic loci in the genomes of modern humans
outside of Africa. HLA types from Denisovans and Neanderthal represent more
than half the HLA alleles ofmodern Eurasians, indicating strong positive
selection for these introgressed alleles.
Figure10:Dermoplastic reconstruction of a Neanderthal
H. floresiensis
H. floresiensis, which lived from approximately 100,000 to 12,000 before
present, has been nicknamedhobbitfor its small size, possibly a result of
insular dwarfism(Brownet al.2004).H. floresiensisis intriguing both for its
size and its age, being an example of a recent species of the genusHomothat
exhibits derived traits not shared with modern humans. In other words,H.
floresiensisshares a common ancestor with modern humans, but split from the
modern human lineage and followed a distinct evolutionary path. Themain
pg.37
Alleles thought to have originated in Neanderthal and the Denisova hominin
have been identified at several genetic loci in the genomes of modern humans
outside of Africa. HLA types from Denisovans and Neanderthal represent more
than half the HLA alleles ofmodern Eurasians, indicating strong positive
selection for these introgressed alleles.
Figure10:Dermoplastic reconstruction of a Neanderthal
H. floresiensis
H. floresiensis, which lived from approximately 100,000 to 12,000 before
present, has been nicknamedhobbitfor its small size, possibly a result of
insular dwarfism(Brownet al.2004).H. floresiensisis intriguing both for its
size and its age, being an example of a recent species of the genusHomothat
exhibits derived traits not shared with modern humans. In other words,H.
floresiensisshares a common ancestor with modern humans, but split from the
modern human lineage and followed a distinct evolutionary path. Themain
Alleles thought to have originated in Neanderthal and the Denisova hominin
have been identified at several genetic loci in the genomes of modern humans
outside of Africa. HLA types from Denisovans and Neanderthal represent more
than half the HLA alleles ofmodern Eurasians, indicating strong positive
selection for these introgressed alleles.
Figure10:Dermoplastic reconstruction of a Neanderthal
H. floresiensis
H. floresiensis, which lived from approximately 100,000 to 12,000 before
present, has been nicknamedhobbitfor its small size, possibly a result of
insular dwarfism(Brownet al.2004).H. floresiensisis intriguing both for its
size and its age, being an example of a recent species of the genusHomothat
exhibits derived traits not shared with modern humans. In other words,H.
floresiensisshares a common ancestor with modern humans, but split from the
modern human lineage and followed a distinct evolutionary path. Themain
pg.37
Alleles thought to have originated in Neanderthal and the Denisova hominin
have been identified at several genetic loci in the genomes of modern humans
outside of Africa. HLA types from Denisovans and Neanderthal represent more
than half the HLA alleles ofmodern Eurasians, indicating strong positive
selection for these introgressed alleles.
Figure10:Dermoplastic reconstruction of a Neanderthal
H. floresiensis
H. floresiensis, which lived from approximately 100,000 to 12,000 before
present, has been nicknamedhobbitfor its small size, possibly a result of
insular dwarfism(Brownet al.2004).H. floresiensisis intriguing both for its
size and its age, being an example of a recent species of the genusHomothat
exhibits derived traits not shared with modern humans. In other words,H.
floresiensisshares a common ancestor with modern humans, but split from the
modern human lineage and followed a distinct evolutionary path. Themain
pg.37
Alleles thought to have originated in Neanderthal and the Denisova hominin
have been identified at several genetic loci in the genomes of modern humans
outside of Africa. HLA types from Denisovans and Neanderthal represent more
than half the HLA alleles ofmodern Eurasians, indicating strong positive
selection for these introgressed alleles.
Figure10:Dermoplastic reconstruction of a Neanderthal
H. floresiensis
H. floresiensis, which lived from approximately 100,000 to 12,000 before
present, has been nicknamedhobbitfor its small size, possibly a result of
insular dwarfism(Brownet al.2004).H. floresiensisis intriguing both for its
size and its age, being an example of a recent species of the genusHomothat
exhibits derived traits not shared with modern humans. In other words,H.
floresiensisshares a common ancestor with modern humans, but split from the
modern human lineage and followed a distinct evolutionary path. Themain
pg.38
find was a skeleton believed to be a woman of about 30 years of age. Found in
2003 it has been dated to approximately 18,000 years old. The living woman
was estimated to be one meter in height, with a brain volume of just 380cm
3
(considered small fora chimpanzee and less than a third of theH. sapiens
average of 1400cm
3
).
However, there is an ongoing debate over whetherH. floresiensisis indeed a
separate species(Argueet al.2006).Martinet al.(2006)hold thatH.
floresiensiswas a modernH. sapienswith pathological dwarfism.This
hypothesis is supported in part, because some modern humans who live on
Flores, the island where the skeleton was found, are pygmies. This, coupled
with pathological dwarfism, could possibly create a hobbit-like human. The
other major attack onH. floresiensisis that it was found with tools only
associated withH. sapiens.
The hypothesis of pathological dwarfism, however, fails to explain additional
anatomical features that are unlike those of modern humans (diseased or not)
but much like those of ancient members of our genus. Aside from cranial
features, these features include the form of bones in the wrist, forearm,
shoulder, knees, and feet. Additionally, this hypothesis fails to explain the find
of multiple examples of individuals with these same characteristics, indicating
they were common to a large population, and not limited to one individual.
find was a skeleton believed to be a woman of about 30 years of age. Found in
2003 it has been dated to approximately 18,000 years old. The living woman
was estimated to be one meter in height, with a brain volume of just 380cm
3
(considered small fora chimpanzee and less than a third of theH. sapiens
average of 1400cm
3
).
However, there is an ongoing debate over whetherH. floresiensisis indeed a
separate species(Argueet al.2006).Martinet al.(2006)hold thatH.
floresiensiswas a modernH. sapienswith pathological dwarfism.This
hypothesis is supported in part, because some modern humans who live on
Flores, the island where the skeleton was found, are pygmies. This, coupled
with pathological dwarfism, could possibly create a hobbit-like human. The
other major attack onH. floresiensisis that it was found with tools only
associated withH. sapiens.
The hypothesis of pathological dwarfism, however, fails to explain additional
anatomical features that are unlike those of modern humans (diseased or not)
but much like those of ancient members of our genus. Aside from cranial
features, these features include the form of bones in the wrist, forearm,
shoulder, knees, and feet. Additionally, this hypothesis fails to explain the find
of multiple examples of individuals with these same characteristics, indicating
they were common to a large population, and not limited to one individual.
pg.39
Figure11:Restoration model ofHomo floresiensis
H. sapiens
H. sapiens(sapiensisaLatinword which means"wise" or "intelligent") have
lived from about 250,000 years ago to the present. Between 400,000 years ago
and the second interglacial period in the Middle Pleistocene, around 250,000
years ago, the trend in skull expansion and the elaboration of stone tool
technologies developed, providing evidence for a transition fromH. erectusto
H. sapiens. The direct evidence suggests there was a migration ofH. erectus
out of Africa, then a further speciation ofH. sapiensfromH. erectusin Africa.
A subsequent migration within and out of Africa eventually replaced the earlier
dispersedH. erectus. This migration and origin theory is usually referred to as
therecent single originor Out of Africa theory. Current evidence does not
preclude some multiregional evolution or some admixture of the migrantH.
pg.39
Figure11:Restoration model ofHomo floresiensis
H. sapiens
H. sapiens(sapiensisaLatinword which means"wise" or "intelligent") have
lived from about 250,000 years ago to the present. Between 400,000 years ago
and the second interglacial period in the Middle Pleistocene, around 250,000
years ago, the trend in skull expansion and the elaboration of stone tool
technologies developed, providing evidence for a transition fromH. erectusto
H. sapiens. The direct evidence suggests there was a migration ofH. erectus
out of Africa, then a further speciation ofH. sapiensfromH. erectusin Africa.
A subsequent migration within and out of Africa eventually replaced the earlier
dispersedH. erectus. This migration and origin theory is usually referred to as
therecent single originor Out of Africa theory. Current evidence does not
preclude some multiregional evolution or some admixture of the migrantH.
pg.39
Figure11:Restoration model ofHomo floresiensis
H. sapiens
H. sapiens(sapiensisaLatinword which means"wise" or "intelligent") have
lived from about 250,000 years ago to the present. Between 400,000 years ago
and the second interglacial period in the Middle Pleistocene, around 250,000
years ago, the trend in skull expansion and the elaboration of stone tool
technologies developed, providing evidence for a transition fromH. erectusto
H. sapiens. The direct evidence suggests there was a migration ofH. erectus
out of Africa, then a further speciation ofH. sapiensfromH. erectusin Africa.
A subsequent migration within and out of Africa eventually replaced the earlier
dispersedH. erectus. This migration and origin theory is usually referred to as
therecent single originor Out of Africa theory. Current evidence does not
preclude some multiregional evolution or some admixture of the migrantH.
Figure11:Restoration model ofHomo floresiensis
H. sapiens
H. sapiens(sapiensisaLatinword which means"wise" or "intelligent") have
lived from about 250,000 years ago to the present. Between 400,000 years ago
and the second interglacial period in the Middle Pleistocene, around 250,000
years ago, the trend in skull expansion and the elaboration of stone tool
technologies developed, providing evidence for a transition fromH. erectusto
H. sapiens. The direct evidence suggests there was a migration ofH. erectus
out of Africa, then a further speciation ofH. sapiensfromH. erectusin Africa.
A subsequent migration within and out of Africa eventually replaced the earlier
dispersedH. erectus. This migration and origin theory is usually referred to as
therecent single originor Out of Africa theory. Current evidence does not
preclude some multiregional evolution or some admixture of the migrantH.
pg.39
Figure11:Restoration model ofHomo floresiensis
H. sapiens
H. sapiens(sapiensisaLatinword which means"wise" or "intelligent") have
lived from about 250,000 years ago to the present. Between 400,000 years ago
and the second interglacial period in the Middle Pleistocene, around 250,000
years ago, the trend in skull expansion and the elaboration of stone tool
technologies developed, providing evidence for a transition fromH. erectusto
H. sapiens. The direct evidence suggests there was a migration ofH. erectus
out of Africa, then a further speciation ofH. sapiensfromH. erectusin Africa.
A subsequent migration within and out of Africa eventually replaced the earlier
dispersedH. erectus. This migration and origin theory is usually referred to as
therecent single originor Out of Africa theory. Current evidence does not
preclude some multiregional evolution or some admixture of the migrantH.
pg.39
Figure11:Restoration model ofHomo floresiensis
H. sapiens
H. sapiens(sapiensisaLatinword which means"wise" or "intelligent") have
lived from about 250,000 years ago to the present. Between 400,000 years ago
and the second interglacial period in the Middle Pleistocene, around 250,000
years ago, the trend in skull expansion and the elaboration of stone tool
technologies developed, providing evidence for a transition fromH. erectusto
H. sapiens. The direct evidence suggests there was a migration ofH. erectus
out of Africa, then a further speciation ofH. sapiensfromH. erectusin Africa.
A subsequent migration within and out of Africa eventually replaced the earlier
dispersedH. erectus. This migration and origin theory is usually referred to as
therecent single originor Out of Africa theory. Current evidence does not
preclude some multiregional evolution or some admixture of the migrantH.
pg.40
sapienswith existingHomopopulations. This is a hotly debated area of
Paleoanthropology.
Stanley (1998)established that humans are genetically highly homogenous;
that is, the DNA of individuals is more alike than usual for most species, which
may have resulted from their relatively recent evolution or the possibility of a
population bottleneck resulting from cataclysmic natural events such as the
Toba catastrophe. Distinctive genetic characteristics have arisen, however,
primarily as the result of small groups of people moving into new
environmental circumstances. These adapted traits are a very small component
of theHomo sapiensgenome, but include various characteristics such as skin
color and nose form, in addition to internal characteristics such as the ability to
breathe more efficiently at high altitudes.
H. sapiens idaltu, from Ethiopia, is an extinct sub-species from about 160,000
years ago.
sapienswith existingHomopopulations. This is a hotly debated area of
Paleoanthropology.
Stanley (1998)established that humans are genetically highly homogenous;
that is, the DNA of individuals is more alike than usual for most species, which
may have resulted from their relatively recent evolution or the possibility of a
population bottleneck resulting from cataclysmic natural events such as the
Toba catastrophe. Distinctive genetic characteristics have arisen, however,
primarily as the result of small groups of people moving into new
environmental circumstances. These adapted traits are a very small component
of theHomo sapiensgenome, but include various characteristics such as skin
color and nose form, in addition to internal characteristics such as the ability to
breathe more efficiently at high altitudes.
H. sapiens idaltu, from Ethiopia, is an extinct sub-species from about 160,000
years ago.
pg.41
Figure12.Currentview of the temporal and geogr aphical distribution of hominid
populations.
pg.41
Figure12.Currentview of the temporal and geogr aphical distribution of hominid
populations.
pg.41
Figure12.Currentview of the temporal and geogr aphical distribution of hominid
populations.
Figure12.Currentview of the temporal and geogr aphical distribution of hominid
populations.
pg.41
Figure12.Currentview of the temporal and geogr aphical distribution of hominid
populations.
pg.41
Figure12.Currentview of the temporal and geogr aphical distribution of hominid
populations.
pg.42
10.0HOMO SAPIENSTAXONOMY
The cladistic line of descent (taxonomic rank) ofHomo sapiens(modern
humans) is as follows:
Taxonomic
rank
Name Common name Millions
of
years ago
Domain Eukaryota Cells with anucleus 2,100
Kingdom Animalia Animals 590
Phylum Chordata Vertebrates and closely related invertebrates530
Subphylum Vertebrata Vertebrates 505
Superclass Tetrapoda Tetrapods 395
Unranked Amniota Amniotes, tetrapods that are fully terrestrially-
adapted
340
Class Mammalia Mammals 220
Order Primates Primates 75
Superfamily Hominoidea Apes 28
Family Hominidae Great apes(Humans, chimpanzees, bonobos,
gorillas, and orangutans)
15
Subfamily Homininae Humans, chimpanzees, bonobos, and gorillas8
Tribe Hominini GeneraHomoandAustralopithecus 5.8
Subtribe Hominina Contains only the GenusHomo 2.5
Genus Homo Humans 2.5
Species Homo sapiens
archaic
Modern humans 0.5
Subspecies Homo sapiens
sapiens
Fully anatomically modern humans 0.2
Table 1. Homo sapiens taxonomy
10.0HOMO SAPIENSTAXONOMY
The cladistic line of descent (taxonomic rank) ofHomo sapiens(modern
humans) is as follows:
Taxonomic
rank
Name Common name Millions
of
years ago
Domain Eukaryota Cells with anucleus 2,100
Kingdom Animalia Animals 590
Phylum Chordata Vertebrates and closely related invertebrates530
Subphylum Vertebrata Vertebrates 505
Superclass Tetrapoda Tetrapods 395
Unranked Amniota Amniotes, tetrapods that are fully terrestrially-
adapted
340
Class Mammalia Mammals 220
Order Primates Primates 75
Superfamily Hominoidea Apes 28
Family Hominidae Great apes(Humans, chimpanzees, bonobos,
gorillas, and orangutans)
15
Subfamily Homininae Humans, chimpanzees, bonobos, and gorillas8
Tribe Hominini GeneraHomoandAustralopithecus 5.8
Subtribe Hominina Contains only the GenusHomo 2.5
Genus Homo Humans 2.5
Species Homo sapiens
archaic
Modern humans 0.5
Subspecies Homo sapiens
sapiens
Fully anatomically modern humans 0.2
Table 1. Homo sapiens taxonomy
pg.43
11.0CONCLUSION
ArchaicHomo sapiens, the forerunner of anatomically modern humans,
evolved between 500,000 and 250,000 years ago. Recent DNA evidence
suggests that several haplotypes of Neanderthal origin are present among all
non-Africanpopulationsand Neanderthals and other hominids, such as
Denisova homininmay have contributed up to 6% of their genome to present-
day humans, suggestive of a limited inter-breeding between these species.
Anatomically modern humans evolved from archaicHomo sapiensin the
Middle Paleolithic, about 200,000 years ago. The transition to behavioral
modernity with the development of symbolic culture, language, and specialized
lithic technology happened around 50,000 years ago according to many
anthropologists although some suggest a gradual change in behavior over a
longer time span.It can therefore be concluded that man evolved from lower
primates.
11.0CONCLUSION
ArchaicHomo sapiens, the forerunner of anatomically modern humans,
evolved between 500,000 and 250,000 years ago. Recent DNA evidence
suggests that several haplotypes of Neanderthal origin are present among all
non-Africanpopulationsand Neanderthals and other hominids, such as
Denisova homininmay have contributed up to 6% of their genome to present-
day humans, suggestive of a limited inter-breeding between these species.
Anatomically modern humans evolved from archaicHomo sapiensin the
Middle Paleolithic, about 200,000 years ago. The transition to behavioral
modernity with the development of symbolic culture, language, and specialized
lithic technology happened around 50,000 years ago according to many
anthropologists although some suggest a gradual change in behavior over a
longer time span.It can therefore be concluded that man evolved from lower
primates.
pg.44
12.0REFERENCES
Argue D., Donlon D., Groves C., Wright R, (2006). "Homo floresiensis:
microcephalic, pygmoid, Australopithecus, or Homo?".J. Hum. Evol.
51(4): 360–74.
Bill Bryson (2004). “The Mysterious Biped”.A Short History of Nearly
Everything. Random House, Inc. pp.522–543.
Bokma, F., van den Brink, V., Stadler, T. (2012). "Unexpectedly Many Extinct
Hominins".Evolution66(9): 2969–74
Brown P., Sutikna T., Morwood M.J., (2004). "A new small-bodied hominin
from the Late Pleistocene of Flores, Indonesia".Nature431(7012): pp.
1055–1061.
Brown, T.A. (2010). "Human evolution: Stranger from Siberia".Nature464
(7290): pp. 838–839.
Brues, A.M., Snow, C.C. (1965). "Physical Anthropology".Biennial Review of
Anthropology4: pp. 1–39
David W.C., (2004).Hominid adaptations and extinctions. UNSW Press. p.76.
Harvati K (2003). "The Neanderthal taxonomic position: models of intra-and
inter-specific craniofacial variation".J. Hum. Evol.44(1): 107–32.
Hebsgaard M.B., Wiuf C., Gilbert M.T., Glenner H., Willerslev E (2007).
"Evaluating Neanderthal genetics and phylogeny".J. Mol. Evol.64(1):
50–60.
Herrera, K. J., Somarelli, J. A., Lowery, R. K., Herrera, R. J. (2009). "To what
extent did Neanderthals and modern humans interact?".Biological
Reviews84(2): 245–257.
Idodo-Umeh, G. (1996). College Biology. Petroleum TrustFund Low Price ed.
Idodo-Umeh Publishers Limited. Benin City, Nigeria, 609 pp.
12.0REFERENCES
Argue D., Donlon D., Groves C., Wright R, (2006). "Homo floresiensis:
microcephalic, pygmoid, Australopithecus, or Homo?".J. Hum. Evol.
51(4): 360–74.
Bill Bryson (2004). “The Mysterious Biped”.A Short History of Nearly
Everything. Random House, Inc. pp.522–543.
Bokma, F., van den Brink, V., Stadler, T. (2012). "Unexpectedly Many Extinct
Hominins".Evolution66(9): 2969–74
Brown P., Sutikna T., Morwood M.J., (2004). "A new small-bodied hominin
from the Late Pleistocene of Flores, Indonesia".Nature431(7012): pp.
1055–1061.
Brown, T.A. (2010). "Human evolution: Stranger from Siberia".Nature464
(7290): pp. 838–839.
Brues, A.M., Snow, C.C. (1965). "Physical Anthropology".Biennial Review of
Anthropology4: pp. 1–39
David W.C., (2004).Hominid adaptations and extinctions. UNSW Press. p.76.
Harvati K (2003). "The Neanderthal taxonomic position: models of intra-and
inter-specific craniofacial variation".J. Hum. Evol.44(1): 107–32.
Hebsgaard M.B., Wiuf C., Gilbert M.T., Glenner H., Willerslev E (2007).
"Evaluating Neanderthal genetics and phylogeny".J. Mol. Evol.64(1):
50–60.
Herrera, K. J., Somarelli, J. A., Lowery, R. K., Herrera, R. J. (2009). "To what
extent did Neanderthals and modern humans interact?".Biological
Reviews84(2): 245–257.
Idodo-Umeh, G. (1996). College Biology. Petroleum TrustFund Low Price ed.
Idodo-Umeh Publishers Limited. Benin City, Nigeria, 609 pp.
pg.45
Kordos L and Begun D R (2001). "Primates from Rudabánya: allocation of
specimens to individuals, sex and age categories".J. Hum. Evol.40
(1): 17–39.
Krings M., Stone A., Schmitz R.W., Krainitzki H., Stoneking M., Pääbo S
(1997). "Neandertal DNAsequences and the origin of modern
humans".Cell90(1): 19–30.
Lewin, Roger (1988). "Hip Joints: Clues to Bipedalism." Science. Volume 241.
1433pp.
Martin R.D., Maclarnon A.M., Phillips J.L., Dobyns W.B., (2006). "Flores
hominid: new species or microcephalic dwarf?".The anatomical
record. Part A, Discoveries in molecular, cellular, and evolutionary
biology288(11): 1123–45.
Reich D., Green R.E., Kircher M, (2010). "Genetic history of an archaic
hominin group from Denisova Cave in Siberia".Nature468(7327):
1053–60.
Srivastava (2009).Morphology Of The Primates And Human Evolution. PHI
Learning Pvt. Ltd. p.87
Stanley H.A., (1998). "Late Pleistocenehuman population bottlenecks,
volcanic winter, and differentiation of modern humans".Journal of
Human Evolution34(6): 623–651.
Strait D.S., Grine F.E., Moniz M.A., (1997). "A reappraisal of early hominid
phylogeny".J. Hum. Evol.32(1): 17–82.
Wood B., Collard M., (1999). The changing face of Genus Homo. Evol. Anth.
8(6) 195-207
Kordos L and Begun D R (2001). "Primates from Rudabánya: allocation of
specimens to individuals, sex and age categories".J. Hum. Evol.40
(1): 17–39.
Krings M., Stone A., Schmitz R.W., Krainitzki H., Stoneking M., Pääbo S
(1997). "Neandertal DNAsequences and the origin of modern
humans".Cell90(1): 19–30.
Lewin, Roger (1988). "Hip Joints: Clues to Bipedalism." Science. Volume 241.
1433pp.
Martin R.D., Maclarnon A.M., Phillips J.L., Dobyns W.B., (2006). "Flores
hominid: new species or microcephalic dwarf?".The anatomical
record. Part A, Discoveries in molecular, cellular, and evolutionary
biology288(11): 1123–45.
Reich D., Green R.E., Kircher M, (2010). "Genetic history of an archaic
hominin group from Denisova Cave in Siberia".Nature468(7327):
1053–60.
Srivastava (2009).Morphology Of The Primates And Human Evolution. PHI
Learning Pvt. Ltd. p.87
Stanley H.A., (1998). "Late Pleistocenehuman population bottlenecks,
volcanic winter, and differentiation of modern humans".Journal of
Human Evolution34(6): 623–651.
Strait D.S., Grine F.E., Moniz M.A., (1997). "A reappraisal of early hominid
phylogeny".J. Hum. Evol.32(1): 17–82.
Wood B., Collard M., (1999). The changing face of Genus Homo. Evol. Anth.
8(6) 195-207
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