Modern, Early Man Coexisted, Study Says
Startling new research indicates that the evolutionary predecessor of present-day humans--a smaller-brained, thicker-boned, heavy-duty species called Homo erectus--may have lived alongside anatomically modern people for tens of thousands of years in Asia.
The controversial study, reported in today’s issue of the journal Science, suggests that Homo erectus was still alive as recently as 27,000 years ago, about 200,000 years after it was supposed to have become extinct.
According to conventional theory, Homo erectus first appeared in Africa about 1.8 million years ago, and spread through Eurasia until it vanished around 200,000 BC, displaced by slender, handier, brainier Homo sapiens, the species to which all living people belong.
But the new research, by an international team of collaborators, sets an upper age range for putative Homo erectus fossil remains found on the island of Java at only 53,000 years. And the lower estimate overlaps by about 20,000 years the period in which Homo sapiens inhabited that part of southeast Asia.
If both species lived simultaneously in Java, no one knows to what degree they might have interacted, or even interbred. The very possibility that the two groups coexisted in the same place came as a surprise to the scientists themselves.
The U.S.-Canadian-Indonesian team, headed by Carl Swisher of the Berkeley Geochronology Center in California, had set out to obtain new evidence for one of the most furiously disputed questions in modern anthropology: Where and how did the modern form of humans evolve?
There are two principal alternative explanations. The multiregional theory holds that Homo sapiens developed among Homo erectus groups in several parts of the world at more or less the same time, perhaps as advanced newcomers drifted in and added their genes to the local gene pool. That would help explain differences in appearance between, say, Asians and Africans.
The other theory, known as the “Out of Africa” hypothesis, holds that Homo sapiens evolved in one area of Africa about a quarter of a million years ago, and gradually spread, eventually supplanting Homo erectus everywhere without appreciable interbreeding. (Presumably the more artful and language-prone Homo sapiens simply out-competed the earlier model, leading to Homo erectus’ extinction.)
The findings published today, if confirmed by additional tests, would dramatically bolster the “Out of Africa” theory by showing that both species were alive in the same place at the same time.
But many anthropologists disagree over how convincing the new research is. Even if the dates are right, Kimbel said, “it is by no means certain” that the bones analyzed in the new research “do indeed represent Homo erectus.” They are not completely typical of finds elsewhere. For one thing, the Java skull capacity averages around 1,200 cubic centimeters, much larger than the 900-cc average for earlier Homo erectus specimens, though still far below the 1,400- to 1,500-cc volume of modern humans.
