eli5 : how did different animals come from common ancestors

Question

eli5 : how did different animals come from common ancestors

In: 1

Answer 1

Separation.

We and chimpanzees share a common ancestor a couple of million years back. The descendants who became chimps and those that became us lived in different environments and were therefore exposed to different selective pressures, environmental conditions making certain traits favorable and others less favorable.

this is pretty much the ground floor of how speciation works. If you separate a population for long enough, the separated groups will each adapt to their new environment and eventually become incapable of interbreeding due to accumulated genetic differences.