Homo neanderthalensis was a close cousin of modern man. Generally known as Neanderthal man, these short, strong and very tough people inhabited Eurasia for over 150,000 years from about 200,000 ago until just less than 30,000 years ago, when modern man superceded them.
The mystery has always been - why did Neanderthals vanish? Was it climate, genetics, an inability to compete with the interlopers from Africa or something more sinister, like extermination by genocide?
The answer is complex and seems to be rooted in the events that began some 45,000 years ago. At that time, most of the Neanderthal range was beset not by a long protracted ice age, something that Neanderthals had survived in the past and were well equipped to survive, but rather by a rapid and violent fluctuation in climate and environment that would strain the resources of a modern nation to manage.
In the wake of this disaster, Neanderthals vanished from most of their former holdings. It might be expected that modern man might have filled the gap presented by this dieing off but that does not seem to have been the case. Instead, Neanderthals began gradually to re-occupy their old territories.
But modern investigatory techniques based on mitochondrial DNA find a big difference in the peoples who occupied Eurasia in the second wave of occupation. Whereas the DNA of Neanderthals prior to the reoccupation show broad genetic diversity, post re-occupation samples show a highly restricted gene pool. Apparently the Neanderthal resurgence occurred only because a restricted group of survivors supplied the genetic material.
This is not a promising formula for long term survival.
It has also been suggested that, as the modern or Cro magnan peoples flooded into Neanderthal lands, the two species interbred and the superior numbers of the newcomers genetically overwhelmed their older cousins, until all trace of them has disappeared. This phenomenon has been observed in animal populations where one group of organisms swamps a lesser population where the two populations are capable of interbreeding.
Were this to have been the case fossil remains of a number of obvious hybrids would be expected, but conclusive evidence of such is very difficult to document. Breeding out, then, would not seem to be a major component of Neanderthal extinction.
It does seem that the very strengths that made Neanderthals able to survive during the ice ages may have worked against them in the newer environment, which was one of open plains and savannahs, quite unlike the heavy forests that prevailed during Neanderthal hay day. The ambush techniques Neanderthals presumably used for taking prey would not have worked well in the open environment where the more agile modern humans, armed with missile weapons would have a decided advantage in the competition for game animals.
These possibilities seem to indicate that the decline and eventual extinction of the Neanderthal race was due to the shock to their genetic base delivered by the climatic events of 45,000 years ago and thereabouts. The change in climatic conditions made their traditional hunting methods suspect, and in the face of a superior competitor they did not have time to adjust. Finally, a certain amount of “genetic swamping” may have indeed taken place, with evidence of same merely awaiting the next archeological discovery.
In any event, while it seems that modern man did contribute to some extent to the demise of the Neanderthal there is some comfort perhaps to be taken that no direct evidence of genocidal warfare has yet been discovered. Modern man's involvement in Neanderthal extinction would appear to be accidental and incidental, and not deliberate.