Its hard to read this sometimes when they make inncorrect historical statements. This is not my expertise, but its been studied and confimred both sub human races surived. True, one was being pushed to the brink of extinction but it was later discovered that peace eventually came around and the two joined and had offsprings between them. Exactly how this played out is any ones guess but one can speculate it had to do with leader(s) making the first move by doing the nasty or perhaps comming to some sort of understanding, maybe a bigger threat at the time.