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Washington Post
"Fossil Find May Back 'Out of Africa' Theory"
By Guy Gugliotta
Washington Post Staff Writer
Thursday, June 12, 2003; Page A01
Scientists working in northeast Ethiopia have unearthed the 160,000-year-old remains of two adults and a child, providing the oldest fossil evidence ever found of how modern humans evolved and a new indication that they arose from a common African ancestor. The remains -- fragments of three skulls found near the site of an ancient freshwater lake -- are about 60,000 years older than the oldest previously known specimen of Homo sapiens, and serve as an anatomical bridge between earlier human ancestors found in Africa and the fully modern humans who began appearing throughout the world about 100,000 years ago. The discovery fills a temporal and geographical gap in the evolutionary record and provides new evidence for the "out-of-Africa" theory, which holds that modern humans evolved as a single species and not as the result of interbreeding with human precursors -- especially the European Neanderthals. "This is a big, robust individual," said paleoanthropologist Tim D. White in describing the most complete of the three skulls. "I can't tell you [how tall he is], but we're not talking about a little man. This is a very large, muscular adult male. If you had a rugby team, you'd want this guy." White, from the University of California at Berkeley, led a multinational team that discovered the remains in the rich fossil beds near Herto village in Ethiopia's Middle Awash region, about 140 miles northeast of the capital of Addis Ababa. The team's findings were reported today in the journal Nature. "The new discovery clearly lends more support to the out-of-Africa hypothesis," said Harvard University paleoarchaeologist Ofer Bar-Yosef, who noted that genetic studies over the past decade have also generally supported that theory. "But whether or not it provides closure of the debate, it is an extremely important discovery because it closes a geographical gap." Before the latest discoveries, remains of what appeared to be modern humans from approximately the same period had been found in Africa, Bar-Yosef said. "But if the dates were good, the morphological evidence [defining the fossil as a modern human] was not. When the physical evidence was good, the dating was not." The Herto fossils help fill in the time sequence and may reflect the actual movement of early humans heading north out of Africa to the Middle East and the rest of the world. Scientists have found modern human fossils 100,000 years old in Israel. White described the Herto skulls as "near-modern" but sharing characteristics of pre-human species: "The brow ridges are very strong, and the area of the neck muscle attachment is very robust," giving the individuals a very powerful aspect, even though the facial features are generally recognizable as modern. "When you add these new fossils to past discoveries and genetics, the weight of evidence that modern humans basically came from Africa is very large," White said. "There will always be skeptics, but their arguments are becoming increasingly lawyerlike." However, some of those who believe in the multiple-origins, interbreeding hypothesis, known as "multi-regionalists," argued that White's team has not proven anything. "He gave us a nice piece of evidence that places the fossils in a nice sequence in Africa," said University of Michigan anthropologist ******* Wolpoff, a leading multi-regionalist. "But then he makes a jump -- saying that since this fits into a sequence, then this is the origin of all humans." The weakness of the out-of-Africa school, Wolpoff said, is that it depends on the idea that all earlier species went extinct and were replaced, without interbreeding, by a single new modern human from Africa. In this debate, the Herto find is "not new information," Wolpoff said. "It's just another fossil." The Middle Awash team, which included American, Ethiopian, French and Japanese scientists, found the Herto site in 1997, when White spotted the fossil skull of a butchered hippopotamus and stone tools in sandy sediment. The Middle Awash region, which is dotted with exposed rock strata dating back millions of years, has been the source of several path-breaking discoveries, including Ardipithecus ramidus, which, at 4.4 million to 5.8 million years old, is the oldest apelike human ancestor yet found. After years of careful excavation, cleaning, assembly and dating, the Herto team had the nearly complete skulls -- without jawbones -- of one male adult and a child between 6 and 7 years old, as well as the brain pan -- the portion of the skull that holds the brain -- of a second adult. The team also found bone fragments or teeth from seven other individuals. In what White described as "a fascinating twist to the story," the excavators found no bones from any part of the body except the head, "and we don't miss bones." White said the team suspected that the heads had been removed before they came to rest in Herto. White also suggested that the brain pan -- apparently scored with a stone tool -- and the child's skull, "polished" as though it had been handled by many hands, had ritual significance. The skull of the robust adult male had been cut twice with a tool, White said. White said the team used a combination of chemical tests and geological analysis to fix the age of the finds to between 154,000 and 160,000 years old. The tools recovered from the site included both crude, early Stone Age hand axes and sharper stone flakes identified with the Middle Stone Age. Hippopotamus and buffalo bones near the site showed signs of pounding to remove the marrow, White said. The team said it could find no evidence of any anatomical linkage between the Herto fossils and Neanderthals. Instead, White said, the new discoveries appeared to represent a transitional phase between earlier human ancestors and modern humans: "These people are separated from us by 10,000 generations," White said. "Yet, in their faces, we see many of the features that we see in our own."
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