The Neanderthal Next Door?

Ana Pinto is shedding some light on the controversial Neanderthal-to-human transition. A Spanish scientist, Pinto completed postdoctoral studies earlier this year at Arizona State University’s Institute of Human Origins. Her research at the Sopeña cave site in northern Spain is catching the attention of paleoanthropologists around the world.

As background, consider that two major competing theories currently exist among scientists to explain how and why modern humans replaced Neanderthals 40,000 years ago as the only human species in Europe.

The leading hypothesis is known as the “Out of Africa” theory. It is championed chiefly by Chris Stringer with the Natural History Museum in London. According to this theory, some 500,000 years ago a hominid species left Africa and flourished in Europe, eventually becoming Neanderthals. Then around 38,000 B.C., proponents of this theory say that anatomically modern humans entered Europe from Africa. They set up their own culture, out-competing or replacing the Neanderthals.

Milford Wolpoff is a University of Michigan anthropologist. He rejects the idea that early modern humans were genetically separate from Neanderthals. He proposes a “multiregional” theory. This theory suggests that some of today’s humans bear the genetic mark of interbreeding between Neanderthals and early humans.

Instead of replacing Neanderthals, Wolpoff thinks that modern humans genetically integrated with them. He cites certain morphological coincidences as evidence for this genetic mixing.

Pinto leans toward the “Out of Africa” theory. She suggests that cultural, climatic, and behavioral differences might have played a large role in modern humans replacing Neanderthals. However, she does not rule out the possibility of some genetic mixing.

Some scientists think that evidence left by erosion during a period when ice covered much of Europe provides a clue. They think that conditions during that period were more extreme than during earlier periods when ice covered the area.

Pinto thinks those extreme climate conditions might have had a hard impact on Neanderthals, who fed mainly on large mammals. If the numbers of their prey diminished, their chances for survival would have decreased dramatically. Modern humans may have arrived to a vastly and recently depopulated Europe. Despite that possibility, Pinto thinks it is unlikely that Neanderthals and early modern humans could have avoided each other entirely.

Also unlikely is the perception that Neanderthals were incapable of advanced technology.

Some scientists believe that complex tools discovered at Neanderthal sites must have resulted from the acculturation of Neanderthals by intellectually superior modern humans. French researcher Francisco d’Errico has compiled evidence that suggests Neanderthals and modern humans created similar technology independently. D’Errico thinks that Neanderthals and humans might even have engaged in trade.

Other researchers think that the possibility of such close contact inevitably begs the question of genetic mixing between the two species. Did Neanderthal man and early modern woman (or vice versa) ever go for a proverbial roll in the cave?

Anatomically, and theoretically, the two species are similar enough that intimate relations would have been possible if they encountered one another. Recent genetic evidence seems to discount the possibility that any Neanderthal genes remain in modern humans. But the relatively small sample size leaves the question open to further research.—Michael Price