Sapiens: A Brief History of Humankind

by Yuval Noah Harari

As we shall see in the next chapter, Sapiens were already very different from Neanderthals and Denisovans not only in their genetic code and physical traits, but also in their cognitive and social abilities, yet it appears it was still just possible, on rare occasions, for a Sapiens and a Neanderthal to produce a fertile offspring. So the populations did not merge, but a few lucky Neanderthal genes did hitch a ride on the Sapiens Express. It is unsettling – and perhaps thrilling – to think that we Sapiens could at one time have sex with an animal from a different species, and produce children together.

I have that there are those of us walking around with some Neanderthal genes which makes me wonder if there useful elements to that for medical science. Maybe they had immunities to something that we don't.