The same thing that happened
to Homo erectus.
The Big Bang Theory Season 4, Episode 24
A Homo habilis discovering
his opposable thumbs says, "What?"
The Big Bang Theory Season 1, Episode 6
...Homo habilis would've figured out
to kill the guy with the runny nose.
The Big Bang Theory Season 1, Episode 11
is that Neanderthals and Homo Sapiens
frequently mated with each other.
The Big Bang Theory Season 9, Episode 24
You know, a Homo novus, if you will.
The Big Bang Theory Season 2, Episode 5