If Homo sapiens and Neanderthals are different species, how did they interbreed and produce the fertile offspring needed for modern humans to have some Neanderthal DNA?

Question

I was told that two seperate species couldn’t interbreed and produce fertile offspring, so I don’t understand how we ended up with some Neanderthal DNA.

In: Biology

Answer 1

It’s quite common for separate species to be able to interbreed and produce fertile offspring, what you were told was just the very oversimplified school version. Cats can crossbreed with a number of related species, wolves can cross with dogs and coyotes, Bison can cross with cattle (despite being in different genera!) and dolphins can cross with false killer whales. There are many more examples.