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IN WHICH YEAR EVOLUTION TAKES PLACE?

We cannot watch changes in life directly. They take place over thousands or millions of years. However, scientists cannot find proof that these changes have taken place. Important evidence for evolution comes from fossils, the leftovers of ancient life. When animals or plants die they are pressed into sand or clay. Over millions of years rocks are formed.

FossilsScientists have found out that different fossils are found in rocks of different ages. For example, the oldest rocks of our earth are about 3.8 billion years old. They contain no fossils because there was probably no life at that time. Fossils of bacteria appear in rocks that are about 3.5 billion years old. Fish , reptile and mammal fossils appear in younger rocks. Human fossils are found only in the youngest and highest rock layers.

Fossils also show that certain groups of animals have evolved from other groups. Amphibians evolved from fish that could breathe air and move on land. They had legs but also scales and a fin.


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