Since kangaroos cannot breed with crocodiles wouldn't you say this is a trait humans SHARE with all other animals? The general inability to breed outside our species. We are talking about traits aren't we and the general inability to breed outsides our species is absolutely a trait humans share with almost all life that procreates sexually.
Extremely few species can interbreed. A wolf and coyote are different species but can interbreed and have fertile offspring. So can lions and tigers and some whales and dolphins. Could a human interbreed with a bonobo? Has anyone ever demonstrated that such a union cannot produce an infertile offspring? I expect humans and bonobos cannot interbreed but I don't know this for a fact and would be surprised if they can but I've been surprised before. I seem to recall that the chromosomal difference between humans and apes is no greater than for members of the equine families. Is that correct? Horse, zebras, donkeys, can interbreed and have sterile offspring because of the difference in chromosomal numbers so maybe humans and apes (or chimps/bonobos) can do the same? Wasn't there a hybrid ape back in the 1980's that was the result of mating between two distinct ape species thought not to be able to crossbreed? Was the offspring sterile?
John Thornton