• A Stone Age Murder Mystery
In the decade since a 5,300-year-old freeze-dried body was pulled from a melting glacier in Austria, theories have been advanced about the cause of death. He got caught in an autumn storm, fell into a crevasse, and froze to death. No, he was carried up the mountain in spring and served as a human sacrifice. Or was it arthritis or malnutrition that killed him? Finally, the verdict is in. The Tyrolean ice man Ötzi was shot from behind with an arrow.
The jury on the case, doctors at the General Regional Hospital in Bolzano, the Italian town where Ötzi now rests, discovered the flint arrowhead on X rays while searching for fractures; CT scans confirmed the verdict. Lodged less than an inch from Ötzi's left lung, the arrowhead not only paralyzed his left arm but also shattered his shoulder blade, tearing major blood vessels and causing him to bleed to death, probably within hours. So why did it take investigators 10 years to determine how the ice man died? Apparently the arrowhead escaped detection because radiologists were looking for bone fractures, malformations, or signs of illness—not for arrows.
The motive for the murder remains a mystery. Perhaps Ötzi was ambushed from behind by a rival who was trying to steal his sheep. Or he could have died in battle, says lead detective Eduard Egarter-Vigl, the pathologist who helped coordinate the scientific investigation of the ice man. Bows and arrows were commonly used during this epoch for hunting, so there's no reason to believe they weren't used for fighting too. In any case, it's clear now that Ötzi's end was not a peaceful one. "He died not naturally," says Egarter-Vigl, "but by violence."
— Josie Glausiusz
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• From Our Faithful Correspondent
The editors of Discover wondered recently how the father of evolution would view the arguments bubbling up in the field of human origins, so we asked contributing editor Joseph D'Agnese what Charles Darwin might have said if he were around today:
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| Did all Homo sapiens originate from one tribe in Africa? Paleoanthropologist Milford Wolpoff argues that ancient Homo sapiens skulls found in far-flung regions reveal evidence that both European and African ancestors could have given rise to modern humans. His theory is based in part on comparative analysis of skulls from three locations: (left to right) Belgium, Moravia, and Israel. Photograph courtesy of Wolpoff, M.H., J.D. Hawks, D.W. Frayer, and K. Hunley/Science 291: 293-297 |
I am in receipt of your kind request for news of developments in human evolution in the last year. If you are willing to permit a fossil to comment on other fossils, I shall be delighted to oblige.
Last year paleoanthropologists nearly engaged in fisticuffs over the birthplace of Homo sapiens. Did modern man migrate out of Africa and replace Neanderthals 100,000 years ago? Or did our species decamp from Africa much earlier as hoary, small-brained Homo erectus and evolve simultaneously in several different places across the globe? The out-of-Africa chaps insist their genetic finds conclusively support man's single African origin. But the science of wresting genes from ancient carcasses dates only to 1997.
The Australians kicked off the imbroglio in January with the discovery that mitochondrial DNA extracted from the remains of the anatomically modern, 60,000-year-old Mungo man, found near Lake Mungo in New South Wales, does not match modern human DNA. The team argued that ancient aboriginal predecessors such as Mr. Mungo and his friends—who possessed both frame and countenance not unlike our own—evolved in their time, on their blessèd plot, in the 2 million years since Homo erectus left Africa.
In February a team of Chinese and Australian scientists announced that they had redated the Chinese Homo erectus fossils called Nanjing man. Once believed to be 400,000 years old, the fossils were found to be 580,000 to 620,000 years old after calculating the ratio of thorium to uranium in the limestone layers above and below the dig site. If the dates hold up, it means modern Asians could have easily evolved in isolation. They would not have had to wait for African Homo sapiens to clamber over the steppes 100,000 years ago. The roots of the Asian family tree were already firmly planted.
The challenges didn't end there. At the University of Michigan, paleoanthropologist Milford Wolpoff—multiregionalism's most visible spokesman—weighed in with a paper describing how his team had analyzed 25 ancient skulls from throughout the Old World and determined that three relatively recent ones displayed both local and African ancestry, a finding con-sistent with multiregionalist theory. At the State University of New York in Oneonta, the anthropological geneticist John Relethford showed that just because Neanderthal DNA does not match that of living people does not mean Homo sapiens never consorted with them. The out-of-Africa contingent has been insisting for years that Cro-Magnons simply replaced Neanderthals and that there was no crossbreeding of the species. Remember: If crossbreeding was common, then the evolve-and-replace tenet would begin to look frightfully simplistic.
Just as a number of out-of-Africa chaps were becoming comfortable with the notion that perhaps there had been some hybridisation of the species, a team of scientists from the United States, Finland, Hungary, and South Africa played both sides against the middle. Their analysis of 61 modern humans and some great apes found significant genetic attributes popping up not just in Africa but arising on their own in geographic pockets the world over. Their conclusion: "We suggest that both the out-of-Africa and the multiregional models are too simple to explain the evolution of modern humans."
As you can see, the muddle becomes muddier. I am pleased that you and your staff enjoyed the tropical worms I sent. Next time, perhaps, some carnivorous beetles.
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| Photograph courtesy of the Department of Library Services/American Museum of Natural History |
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• A Crunchy Hominid Taste Treat
Early human ancestors from the species Australopithecus robustus, which emerged in South Africa 2 million years ago, sported large, flat teeth and powerful jaws. So researchers have long assumed they chomped their way through life as plant-eaters. But a study published last January suggests their diet also included a nonvegetarian delicacy: termites.
Lucinda Backwell, a graduate student in paleoanthropology at the University of Witwatersrand in Johannesburg, South Africa, made the discovery while sorting through a collection of 108 tools fashioned by A. robustus from antelope bones. Tiny scratch marks on the ends of some of the tools caught her eye. "At first I thought they were made by wind erosion or water erosion or some hyena, but a pattern suddenly emerged in the striations," Backwell says. Then she realized that the striations just didn't match those on other tools used for digging tubers from soft ground: "When one looked under the microscope, it was clear the tool had penetrated something hard." To determine what had caused the marks, Backwell and her collaborator, Francesco d'Errico of the Institute of Quaternary Prehistory and Geology in France, found bone tools of their own that were approximately the same size—the length of a pen and the width of a thumb. They jabbed these tools into the earth and stabbed them into carcasses and against bone but failed to match the telltale striations. Recollecting that chimpanzees are known to eat termites, Backwell and d'Errico plunged the tools into the hard covering of a termite colony. "We were able to match those fossilized patterns within about five minutes," says Backwell.
The likelihood that our early ancestors ate termites as part of their diet had been predicted by Jane Goodall as early as the 1960s, on the basis of her observations of chimpanzee behavior. "However, this is the first time that anyone has been able to prove it definitively," says Lee Berger, director of the Anthropology Unit for Research and Exploration at the University of Witwatersrand. "The results are a beautiful example of a well-planned experiment."
— Curtis Rist
