1. ORIGEN DE LA VIDA - EVOLUCION DE VIDA.pptx

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1. Theories of the Origin of Life Depend Primarily on Indirect Evidence However, conditions on Earth for the first 100 million years or so were far too harsh to sustain any type of life. Eventually bombardment by meteorites decreased, water appeared on the planet in liquid form, and gases were released by geological activity to form Earth’s atmosphere . These conditions were amenable to the origin of the first life forms . Despite these problems, most scientists agree that life was present on Earth about 3.5 to 3.8 billion years ago To reach this conclusion, biologists rely on indirect evidence. Among the indirect evidence used are molecular fossils