Theories on How Life Could Have Begun.pptx

This lesson discusses the different theories about the creation of life.

1. Theories on How L ife C ould Have B egun

2. What was the first form of life? Life is believed to have existed on earth for billions of years now. Scientists do not know exactly when life began on Earth. However, they can trace how life developed and evolved using some pieces of evidence.

3. Earth is much older than life. Based on radioactive decay studies of rocks, it was revealed that Earth is around 4.5 billion years old – 1 billion years older than the oldest fossils. So how did life begin? Where did it come from?

4. Earth is much older than life. Based on radioactive decay studies of rocks, it was revealed that Earth is around 4.5 billion years old – 1 billion years older than the oldest fossils. So how did life begin? Where did it come from?

5. Theories on how life could have begun

6. 1. Extraterrestrial origin The hypothesis explains that life originated on another planet outside our Solar System. Life was then carried to Earth on a meteorite or an asteroid and colonized Earth. However, this hypothesis has not been proven.

7. 2. Panspermia The theory presumes that the “seed” of life exists all over the universe and can be propagated through space, and that life on Earth originated from those seeds.

8. 3. Divine creation Many people believe that life was put on Earth by divine forces. Creation theories are common to many of the world’s religions and cultures.

9. 4. Origin from nonliving matter Scientist believed that life arose on Earth from inanimate matter after Earth had cooled. They stated that random events probably produced stable molecule that could self-replicate. Then, natural selection favored changes in the rate of reproduction which eventually led to the first cell.