I recall a building scientific consensus that us homo sapeins all evolved from a small group which migrated out of Africa eons ago. Then due to climate and other changed and stressful conditions, we all became, ever so slowly and over ever so long a period of time, the way we all are today. This accounts for the fact that all the so called "races" can make babys together and have interchangable parts!

It is because, darnitall, that we are all the SAME race - just different varieties!

Neanderthals were likely a different branch of the family tree who were unable to compete for scarce resourses with us newcomers.

But - could some still be around today? Dunno, but the worldwide distribution of Sasquatch, Bigfoot, Snowman, etc. stories makes me stop to wonder.