Many people think that everything has a common ancestor, having us all linked in the same tree. I think maybe we came from one of two origins, since life can be created both on land and in water. In some places the to trees would come together and others they would be by themselves. This would explain why some animals stay in water, some cant swim, and some can thrive on both.It can't explain the mutations, but depending on how the first creatures were, it could decrease the amount of mutations created. Just an idea I had to lead to new possibilities.