[RipSawyer]

I was taught that homo sapiens and neanderthal were two separate species, I was also taught that true hybrids are infertile. Modern horses don’t have donkey dna because their hybrid offspring, the mule, is infertile. If homo sapiens and neanderthal were truly two different species how can there be any neanderthal dna in modern humans?

[varmintman]

Same way that banking software and rocket telemetry software can share a few low-level C language math functions. All it means is that some original designer used a few of the same low-level genetic parts on dissimilar projects.

There is zero possibility of us having genes in common with any hominid from interbreeding. Humans exterminated all hominids from the planet other than possibly for a few survivors (bigfoot etc.) surviving in areas which humans could not inhabit. Humans would not have tolerated crossbreeds amongst themselves.

[allmendream]

Coyotes and wolves are different species and they produce fertile offspring.

[PapaBear3625]

I was taught that homo sapiens and neanderthal were two separate species, I was also taught that true hybrids are infertile. Modern horses don’t have donkey dna because their hybrid offspring, the mule, is infertile. If homo sapiens and neanderthal were truly two different species how can there be any neanderthal dna in modern humans?

There couldn't, therefore they were not separate species. There may have been a lot of genetic distance between Cro Mag and Neanderthal, but not enough to bar mixing. For example, although lions and tigers look very different, they can produce fertile offspring.