Neanderthals--those brawny but big-brained cousins of ours--thrived across Europe and Asia for some 300,000 years. Then, in the course of just a few thousand years, they vanished, leaving only some bones, beads, stone tools, an enigmatic burial or two, and a scattering of their genes in our species, Homo sapiens.
Since the discovery of the first Homo neanderthalesis skeleton in 1856, scientists have speculated and argued about what caused their extinction. There have been lots of ideas, including climate change, disease, lack of genetic variability, interbreeding with, competition with, or outright extermination by H. sapiens.
New research using a sophisticated supercomputer model incorporating climate shifts, geography, availability of food, utilization of resources and interbreeding may have solved the mystery. It was us, modern humans at first filtering in from Africa and then expanding our range across Asia and Europe, who did them in.
"It is not a coincidence that Neanderthals vanished just at the time when Homo sapiens started to spread into Europe," says Axel Timmerman, a climate physicist at Pusan National University, in South Korea. "The new computer model simulations show clearly that this event was the first major extinction caused by our own species."
The model that Timmerman developed folded together a huge amount of information. It modeled the climate across northern Africa, Asia and Europe over the 100,000 years that preceded the Neanderthal extinction around 38,000 years ago, regional productivity of potential food sources, population densities of Neanderthals and modern humans across time and space, and interbreeding between the two species.
One conclusion that emerged clearly was that climate change alone was not the cause of the Neanderthal's extinction. This bears out the observation that they had survived hundreds of thousands of years of climate change, including periods of severe glaciation. "Neanderthals lived in Eurasia for the last 300,000 years and adapted to abrupt climate shifts that were even more dramatic than those than occurred during the time of Neanderthal disappearance," says Timmerman. It was only after the arrival of modern humans that Neanderthal populations began an irreversible decline.
Timmerman concludes that the anatomically modern humans who found their way into Eurasia around 50,000 years ago simply out-competed the Neanderthals. His model doesn't specify exactly what differences drove that competitive edge. If, for example, the modern humans simply were able to harvest more food from the environment, or were more resistant to diseases, or managed to raise more children to adulthood--anything that gave them a competitive advantage--that could have been enough to allow them, over the course of thousands of years, to displace and eventually replace the Neanderthals.
We shouldn't be surprised; one way or another the culprit was us.
You can find the f ull, open-source research paper by clicking here. It's worth scrolling down to the appendix, where you can watch movies depicting the influx and growth of the H. sapiens population and the decline and disappearance of the Neanderthals over time and space. Fascinating.
(Article changed on June 21, 2020 at 18:54)