A team at Arizona State University and the University of Colorado (USA) used complex computer modelling to analyse evidence of how human hunter-gatherers responded to dramatic changes during the last Ice Age.
     The researchers used the archaeological record to track human behavioural changes in Late Pleistocene (126,000 - 10,000 BP) Western Eurasia over a period of 100,000 years, and across the equivalent of 1,500 generations of human hunter-gatherers. They applied computer modelling to determine the evolutionary consequences of cultural and biological changes, which included how changes in the movements of modern humans and Neanderthals caused them to interact and interbreed with each other. The results showed that human mobility during the environmental changes associated with the Ice Age increased over time, likely in response to those environmental changes. The modelling suggests the last Ice Age caused the ancestors of modern humans - and Neanderthals - to widen their ranges across Western Eurasia in search of new resources as the climate shifted.
     According to study co-author Julien Riel-Salvatore of the University of Colorado, Denver, this provides new evidence that Neanderthals were more adaptable and resourceful than previously thought, and suggests Neanderthals were gradually absorbed within the expanding modern human populations.
     Michael Barton, study co-author and expert on archaeological applications to computer modelling at Arizona State University, says the modelling predicts the kind of low-level genetic admixture of Neanderthal genes found in the newest studies being published. "In other words, successful behavioural adaptations to severe environmental conditions made Neanderthals, and other non-moderns about whom we know little, vulnerable to biological extinction, but at the same time, ensured they made a genetic contribution to modern populations."

Edited from Arizona State University News, Popular Archaeology (17 November 2011)