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Eugène Morin of Trent University has just published this paper in PNAS, “Evidence for declines in human population densities during the early Upper Paleolithic in western Europe.”

He studied the fluctuations in the zooarchaeological record from the Saint-Césaire site in France. And he found remains of rodents that live in the tundra species which indicate colder conditions. To coincide with the presence of rodents, there was a dramatic decrease in large mammal diversity, except for reindeer. Reindeer populations jumped up from 35 to 87% during this climate change.

An increase in reindeer population inversely relates to human population densities because the diversity of animals that could be hunted shrank severely, and that would have impacted human populations. He concludes, Neandertal populations reduced as Europe’s environment became harsher, with some groups going extinct by 40,000 to 35,000 years ago.

Reindeer jawbone from a site in France

Since 2006, I’ve read several studies going back and forth on climate change as the nail in the coffin for Neandertals. Do you remember the ‘last stand in Gilbraltar‘? That study relied on archaeological remains of a sheltered site in Gibraltar. It also suggested extreme climates affected the extinction of Neandertals. But in September 2007 a study from Max Planck’s Katerina Harvati concluded that catastrophic climate change was not a cause for extinction. Here’s the link to that paper, “Placing late Neanderthals in a climatic context.”

Morin is taking a different angle. He’s saying climate change was a cause for the reduction on Neandertal populations but also that Neandertals gave rise to the first modern humans in Europe! Morin says to National Geographic News that climate stresses may have wrought evolutionary adaptations in surviving Neandertals, leading them to develop characteristics like those of modern humans. And in his the abstract, Morin writes,

“These data suggest that the EUP represented for humans a period of significant niche contraction in western Europe. In this context, the possibility that a modern human expansion occurred in this region seems low. Instead, it is suggested that population bottlenecks, genetic drift, and gene flow prevailed over human population replacement as mechanisms of evolution in humans during the EUP.”

So he’s suggesting that climate change influenced the rise of the first modern humans in Europe from Neandertals. How do you feel about this conclusion?