Sorry for late reply. Yes, this is a serious question. The evolution of one species into the other has never been witnessed because as scientists say it takes thousands if not millions of years. So if it takes so long there should be some form of the between species.
Discussion
1. There are a lot of bones of them. We drove them extinct.
2. remember that in evolution you can't point at an individual and say "this is now another species/race". It so incremental you can never 100% look at some bones and fully tag then as one or another
3. Even evolution never stops. If we didn't kill all of those, their ancestors would have evolved into humans, evolved into something else, or died for not being fit for the environment