I've always been rather puzzled about exactly why the Neanderthals went extinct. When they were first discovered, some two centuries ago, the assumption was that Neanderthals represented an inferior branch of humanity, more brutish than modern man, that inevitably was superseded by the superior traits of modern human beings. Various explanations were provided for why this might have occurred. There might have been wars between the two groups, resulting in the ultimate extermination of Neanderthals by armed force. Our own human ancestors would obviously have been in direct competition with the Neanderthals for food and resources of various types. Perhaps modern human beings were simply better at hunting and gathering than the Neanderthals were, and consumed all available resources, leaving the Neanderthals to die from starvation, or perhaps from exposure to the elements for lack of proper clothing and shelter. Various explanations were presented for this possibility. Possibly human beings were better at communicating verbally than Neanderthals were, for anatomical reasons related the structure of their brains, throats or tongues. This might have allowed them to work better with each other in hunting and gathering activities, and made them more effective than the Neanderthals. It might have also made them better at making tools useful in hunting and gathering.

However, none of these explanations seemed to be particularly compelling. The Neanderthals appeared to have brains as large, or even larger than those of human beings. Neanderthals were at least as intelligent, or more intelligent than modern human beings. Neanderthals were as big and strong, or stronger, than modern human beings. So, why would human beings have been able to defeat Neanderthals in war, had superior communication skills, or been able to out-compete Neanderthals, in any way whatsoever?

In recent decades, with the development of sophisticated DNA technologies for the analysis of human, and non-human remains, it's become quite clear that Neanderthals and modern humans certainly did interbreed, and that perhaps as much as 5% of modern human genetics is derived directly from this inter-species mating between Neanderthals and humans. This interbreeding, perhaps on a rather massive scale, may provide a rather interesting and simple explanation for the apparent "extinction" of Neanderthals.

Neanderthals were a highly specialized species, localized in Northern Europe during the Ice Age, and specialized in dealing with the climatic difficulties of surviving in this region, at that period of time. They were never particularly numerous, because of the extreme challenges of survival in this region, at that particular time. This, of course, meant they were left alone, and hadn't any competition. However, modern human beings spread out of Africa throughout Eurasia, they lived in Africa, India, China, Southeast Asia, and, ultimately, some of them braved the challenges of Ice Age northern Europe, where they encountered the Neanderthals. The Neanderthals were the masters of this region, so, really, our ancestors probably had no choice but to get along with them, to survive. And, that inevitably led to interbreeding. Far from exterminating the Neanderthals, or even competing for scarce resources with them, our ancestors might well have been little more than slaves to the Neanderthals. And, of course, slaves make perfectly legitimate breeding stock. And, with large numbers of modern humans infiltrating their territories from around the world, and working as slaves for them, and being used as limitless breeding stock, eventually, of course, the master Neanderthals would come to resemble modern man, more and more. Until, they became modern men, more or less, anyway.