system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: If Neanderthals became extinct by breeding with humans, how were they a different species in the first place?
gpt
A lot of people classify both Neanderthals and modern humans as subspecies of the same species: *Homo sapiens neanderthalensis* and *Homo sapiens sapiens*. That’s still up for debate, but the interbreeding is a strong signal in its favor. There’s still a lot we don’t understand about the disappearance of the Neanderthals (and the Denisovans with whom we also interbred) but it likely came down to modern humans out-competing them.