Findings explain why they disappeared as a distinct population
DENVER – Anthropologists using computer modeling to determine how early hominins adapted to climate change during the last Ice Age have gained new insights into why Neanderthals disappeared as a distinct population some 30,000 years ago.
The scientists believe Neanderthals interbred with more numerous modern humans until they ceased to exist as their own population.
“It’s been long believed that Neanderthals were outcompeted by fitter modern humans and they could not adapt,” said Julien Riel-Salvatore, Ph.D., assistant professor of anthropology at the University of Colorado Denver. “We are changing the main narrative. Neanderthals were not inferior to modern humans. They were just as adaptable and in many ways simply victims of their own success.”
The findings by Riel-Salvatore and C. Michael Barton, Ph.D., professor of anthropology at Arizona State University, were published Nov. 17 in the journal Human Ecology.
Barton, the lead investigator, said he and Riel-Salvatore used archeological data to track behavioral changes in Western Eurasia over 100,000 years and showed that human mobility increased over time, probably as a result of environmental change.
According to Barton, the last Ice Age saw hunter-gatherers, including both Neanderthals and the ancestors of modern humans, range more widely across Eurasia searching for food during a major shift in the Earth’s climate.
The scientists employed computer modeling to explore the evolutionary consequences of those changes, including how changes in the movements of Neanderthals and modern humans caused them to interact – and interbreed – more often.
The team ran a computer program for the equivalent of 1,500 generations showing that as Neanderthals expanded their yearly ranges, they were slowly absorbed by more numerous modern humans.
“This demographic process is relevant for the Late Pleistocene where hominins we call Neanderthals were a population limited to temperate Western Eurasia and the hominins we call `moderns’ were more widespread across Africa and Asia,” Barton said. “It demonstrates how Neanderthals could disappear as a distinct, regional population even with the same or even greater biological fitness than `modern’ forms.”
Riel-Salvatore said the study offered further evidence that Neanderthals were more flexible and resourceful than previously assumed.
“Neanderthals had proven that they could roll with the punches and when they met the more numerous modern humans, they adapted again,” he said. “But modern humans probably saw the Neanderthals as possible mates . As a result, over time, the Neanderthals died out as a physically recognizable population.”
Barton and Riel-Salvatore pointed out that Neanderthals may no longer exist as a population but live on in all of us.
“Neanderthal genes make up between one and four percent of today’s human genome, especially in those of European descent,” Barton said. “Their legacy lives on in our genome and possibly in our cultural knowledge.”
The paper “Modeling Human Ecodynamics and Biocultural Interactions in the Late Pleistocene of Western Eurasia” is also co-authored by John Martin “Marty” Anderies, an associate professor of computational social science at ASU in the School of Human Evolution and Social Change and the School of Sustainability; and Gabriel Popescu, an anthropology doctoral student in the School of Human Evolution and Social Change at ASU.
The research presented in Human Ecology was supported in part by the National Science Foundation, a Fulbright Senior Research Fellowship and a Fulbright Graduate Student Fellowship.
Barton CM et al. (2011) Modeling Human Ecodynamics and Biocultural Interactions in the Late Pleistocene of Western Eurasia. Human Ecology. DOI 10.1007/s10745-011-9433-8
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