| A simple google search turned up many sites including this one on the origin of whales, since that is what you asked for.
You are under the misconception that evolution requires major mutations. It doesn't. Every new birth is a mutation; a new combination of DNA that didn't exist before. Cross breeding and hybridization have produced animals significantly different than their ancestors, and that is all evolution does. Bear in mind that deliberate breeding of plants animals for specific traits by humans has only been going on for a few thousand years, yet we have produced numerous variations. Evolution has had hundreds of millions of years. |
