<< News >> Stone-age innovation explains ancient population boom
Submitted by coldrum on Friday, 24 July 2009 Page Views: 6954
DiscoveriesThirty-five thousand years ago, the advent of stone microblades set the stage for the Indian subcontinent's explosive population growth, new research suggests.The easy-to-manufacture tools – also known as microliths – were a vast improvement over larger stone flake tools used previously, says Michael Petraglia, an archaeologist at the University of Oxford, UK, who led the study. Because microblades could be cut from stone more quickly and in higher volumes than flakes, hunting probably became a vastly more efficient endeavour.
"It allows people to more reliably and more cheaply slaughter animals," says Lawrence Guy Straus, a paleoanthropologist at the University of New Mexico in Albuquerque, who was not involved in the study.
Petraglia and his colleagues contend that the beginnings of a global ice age pushed ancient populations of Indians into closer contact – and competition – with one another. "They need to develop new strategies to produce new resources. They invent microlithic technology and it spreads very rapidly."
Though proving causality of any ancient upheaval is difficult, if not impossible, Petraglia's team argue that genetic, environmental and archaeological records make a strong circumstantial case for their theory.
Genetic evidence
Between 30 and 35,000 years ago, the Earth cooled dramatically. In Europe, these changes brought with them massive glaciers, pushing Neanderthals and newly arrived humans into small pockets, and perhaps contact.
In India, however, this ice age shortened the monsoon season and transformed what had been a rather homogenous tropical landscape into a patchwork of savannahs and deciduous forests bordered by desert, Petraglia says.
"When you get more deserts you're getting environmental fragmentation. That is conducive to hunter-gatherers, Petraglia says. "They like mosaic environments because you tend to have a lot of diversity in flora and fauna."
These changes almost certainly would have split up ancient populations, but they could have spurred their growth as well, Petraglia says. By treating the mitochondrial DNA of contemporary Indians as a sort of molecular clock, the researchers documented an expansion in Indian genetic diversity dated to around the time of this ice age.
wild climatic swings.
Read more at New Scientist
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