Did a chill kill Neanderthals? Clues point to climate change
Most anthropologists think Europe’s Neanderthals were out-competed to extinction by anatomically modern humans, but new evidence suggests that climate change played a much bigger role in their demise than previously suspected, a Canadian scientist said this week.
A dramatic cold spell in the region between 40,000 and 35,000 years ago sharply reduced the food supply for Neanderthals, rendering their survival problematic, anthropologist Eugene Morin of Trent University in Peterborough, Canada, reported Monday in the Proceedings of the National Academy of Sciences.
The Neanderthals were distant cousins of humans who lived in Europe about the same time humans made their first appearance there.
The two groups apparently had little interaction and little or no interbreeding until the Neanderthals became extinct between 32,000 and 24,000 years ago.
Evidence from studies of deep-sea sediments indicate that temperatures in Europe dropped by nearly 15 degrees Fahrenheit during the period when Neanderthals were flourishing.
Morin studied the effects of this temperature decline by examining bones and other artifacts from a Neanderthal site at Saint-Cesaire in southwestern France.
Accurately dated bones from the site show that the Neanderthals feasted on bison, horses, red deer and reindeer when the climate was warmer. But as temperatures declined, the proportion of reindeer in their diet increased to 87% from 35%. The proportion of remains of the small tundra-dwelling rodent known as the narrow-skulled vole also increased, confirming the colder weather.
The problem, Morin noted, is that excessive reliance on reindeer as a food source is risky because their populations fluctuate widely. A decline in their numbers would lead to famine and population decline, he said.
Morin speculates that modern humans would have fared even worse in these conditions because, coming from Africa, they would not have adapted to the cold.
He speculates that the frigid conditions may have induced more socialization among the Neanderthals for mutual support and made them more human-like, with the strongest among them surviving to greet the emerging humans many years later and perhaps to breed with them to produce modern Europeans.