Finds unearthed in southeastern India offer a cutting-edge revision of hominid migrations out of Africa more than 1 million years ago that spread pivotal tool-making methods. Makers of a specific style of teardrop-shaped stone hand ax, flat-edged cleavers and other implements that originated in Africa around 1.6 million years ago reached South Asia not long afterward, between 1.5 and 1 million years ago, say archaeologist Shanti Pappu of the Sharma Center for Heritage Education in Tamil Nadu, India and her colleagues.
     Rather than waiting until around 500,000 years ago to head into South Asia, as many researchers have thought, the African hand ax crowd wasted relatively little time before hightailing it to India, Pappu's team concludes.
     Archaeologists categorize stone hand axes and related implements as Acheulian tools. Most researchers regard Homo erectus, a species that originated around 2 million years ago, as the original brains behind Acheulian innovations. "Acheulian tool makers were clearly present in South Asia more than 1 million years ago," Pappu says. Several previous excavations in different parts of India have also yielded Acheulian tools, but these finds lack firm age estimates, she adds.
     H. erectus must have rapidly moved from East Africa to South Asia, proposes archaeologist Robin Dennell of the University of Sheffield in England. Pappu's new finds raise the possibility that 800,000-year-old hand axes previously discovered in southeastern China indicate the presence of H. erectus groups that came from South Asia - or at least exposure of Chinese hominids to Acheulian techniques, Dennell suggests. Prior finds point to a second migration of Acheulian-savvy hominids out of Africa, he says. Homo heidelbergensis - a species first identified in Europe that some researchers now suspect inhabited East Africa and possibly Asia - trekked northward to the Middle East and then westward into Europe by half a million years ago, Dennell hypothesizes.
     Until now, scientific consensus held that Acheulian tool makers, presumably H. erectus, reached the Middle East at least twice, around 1.4 million and 800,000 years ago, but went no further. H. heidelbergensis then took Acheulian implements from Africa to both South Asia and Europe approximately 500,000 years ago in this scenario. If that was the case, even older Chinese hand axes might represent a tool tradition that developed independently of outside influences.
     Any relationship of those Chinese finds to tools unearthed by Pappu's group remains unclear, comments Harvard anthropologist Philip Rightmire. But it's not surprising that H. erectus inhabited South Asia sometime around 1.5 million years ago, he says. Other evidence suggests that H. erectus left Africa for several destinations throughout Asia beginning at least 1.8 million years ago, wielding simple chopping tools. "For now, it's enough to say that Homo erectus introduced Acheulian tools to India," Rightmire says.

Edited from ScienceNews (24 March 2011)