The argument over whether or not Neanderthals and the remaining extant Human species to which you and I belong interbred has been up there in the ether for several generations. Objections to the idea were often fierce, and without the science that permits an unraveling of a genome those objections were as much an utterance from a Pulpit as anything reasonable.
The baby Neanderthal head was too big to pass through the birthing tube of a
darling Human Being. I recall this objection being debated. Not so much in a
lecture hall but in those corridors of power where vast quantities of beer are
consumed. Discussion raged this way and that, but found no resolution. Then it
deteriorated into name calling, head measuring and a series of ancillary
entertainments all of which seemed reasonable at the time.