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10/19/93

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Stanford begins program in human biocultural evolution

STANFORD -- A new program in human biocultural evolution gets under way at Stanford this fall with the addition of archeologist Richard Klein to the faculty.

Klein, at the University of Chicago for 20 years, is teaching the human evolution portion of Stanford's core course in the Human Biology Program this fall, a course on human origins in evolution this winter, and a seminar devoted to modern human origins next spring.

Klein's appointment is divided between the Anthropology Department and the Human Biology Program. He fits well into both because "he has suggested a correlation in space and time" between cultural and biological development in human prehistory, said Bill Durham, professor of anthropology and director of Stanford's Human Biology Program.

The Anthropology Department at Stanford is known mostly for its work on theories of culture, Durham said, while the large undergraduate program in human biology marries social and biological sciences so that students get both in the same quarter and sometimes even in the same lecture. Its graduates go on to a wide range of careers in medicine, government and business.

Klein's 1989 book, The Human Career: Human Biological and Cultural Origins, is "the number one text in its field," Durham said, because it is both scientifically rigorous and integrative of evidence from a variety of perspectives and specialties.

"It summarizes the existing anatomical and archeological data on human origins and then employs these data in a fair and comprehensive evaluation of theories concerning the biological and cultural origins of the species," Durham said.

The Human Career has sold almost 10,000 copies, and the royalties helped make it possible for Klein and his wife, a marketing consultant, to move from Chicago to the Bay Area, he said recently amid stacks of unpacked boxes in his Quad office. Housing is much more expensive here and cars essential, he said. "We didn't own a car because we didn't need one in Chicago," Klein said.

The book sales were a surprise, Klein said, because he did not set out to write a college textbook.

"I wanted to summarize human evolution for myself to see if I was doing the most useful research I could," he said.

His conclusion was to focus on the problem of modern human origins. He has continued with this, even since last February when landmark molecular biological research bearing on the origins of modern humans was seriously disputed in letters to Science. Scientists at Washington University and Pennsylvania State reported statistical flaws in the way the original researchers at the University of California-Berkeley had analyzed the data that they had published in 1987.

The original research involved comparing samples of mitochondrial DNA from 140 living individuals from around the world. Using computers, the geneticists assembled a human ancestral tree based on the similarities and differences in this type of genetic material, which is simpler to track through generations than other DNA, because individuals inherit it only from their mothers.

"What emerged was a tree rooted in Africa with two main branches, one composed only of Africans, and another of some Africans and everyone else," Klein said.

The rate of divergence in mitochondrial DNA suggested we all shared a common female ancestor between roughly 140,000 to 280,000 years ago, he said, which fit well with his and others' archeological data suggesting a very recent common ancestor for all living humans. The mitochondrial DNA supported one of two major competing theories of human evolution - the so-called "Noah's Ark" or "Out-of-Africa" theory.

This theory proposes that all modern humans evolved relatively recently from a small population in Africa whose descendants subsequently swept through the rest of the occupied world, replacing non-modern humans such as the Neanderthals in Europe.

This contrasts with the "Multiregional" theory, which posits that anatomically modern humans evolved simultaneously more or less everywhere where non-modern humans had lived before. Klein said that the fossil record supported the Out-of-Africa theory even before the mitochondrial DNA tree was published. However, the tree had enormous impact on popular thinking, because it seemed more "scientific" and less controversial than the fossils.

Now, it looks as though the geneticists made a major mistake when they failed to understand the assumptions behind the computer program they used to construct their tree. When later researchers employed suitable assumptions, they obtained multiple ancestral trees, which cannot be statistically distinguished from one another. "Some of these other trees rooted in America and Australia, where nobody believes humans originated," Klein said.

There is still important genetic evidence that supports the Out-of-Africa theory, Klein said, "but nothing as compelling as the mitochondrial DNA tree, and now that it has been shelved, the theory once again depends mainly on the fossil record."

In a lecture he delivered recently at the University of Illinois, Klein said that "full closure" on modern human origins may be "beyond our grasp," but that "the accumulation of fresh, high-quality evidence will surely allow us to refine alternative explanations" and to determine which is probably correct in much the same way that a court of law reaches a final verdict on innocence or guilt.

It means a lot more work, he said, not just by archeologists but by geneticists and geochronologists, who provide the methods by which the fossil record is dated.

Klein has produced an important part of the existing record himself, mainly in South Africa, where he has conducted archeological research yearly for the last 25 years. He has also done extensive work in Spain and the former Soviet Union.

He is an unusual paleoanthropologist, Durham said, in that "lots of people have paid lip service to the interrelationship of cultural, biological and environmental change in human evolution, but he has used that interaction as an explanatory tool."

For example, Durham said, Klein has convincingly used his data on animal remains from four cave sites in South Africa to reconstruct the differences in hunting patterns between the inhabitants who lived before and after 40,000 years ago. Before 40,000 years ago, southern Africans apparently did not know how to fish or to hunt birds, and the mammals they obtained were mainly the least dangerous ones. They also do not seem to have fully appreciated variability in the seasonal availability of important resources like fur seals.

Since bones show that the people who lived in southern Africa before 40,000 years ago were anatomically modern or near modern, Klein concluded that "the appearance of the modern physical form preceded the appearance of fully modern behavior."

The evidence for this goes beyond hunting practices to artifacts, he said. People before 40,000 years ago "made much cruder artifacts that changed remarkably little through time and hardly differed over vast areas. They failed to recognize bone, ivory and shell as materials that could be cut, carved or polished into points, needles and so forth, and perhaps in keeping with this, they left us no evidence for art."

After 40,000 years ago, "much more sophisticated artifacts appear; there is rapid turnover in artifact types," he said. "Regional variation in artifact types is striking; bone, ivory and shell artifacts become commonplace; and art is everywhere."

Klein believes that a major neurological change occurred in Africa about 50,000 to 40,000 years ago. The result was a dramatic advance in human ability to adapt to environment via culture, and armed with this ability, fully modern humans were then able to spread to other continents where they replaced the Neanderthals and other non-modern populations. "Conceivably," Klein said, "this neurological change could have occurred in Europe, in which case you and I would be Neanderthals talking about the strange people who used to live in Africa."

The Human Biology Program integrates social science and biology on a teaching level, Klein said. For example, "in the introductory human biology course this fall, Bill Durham has shown how the evolution of lactose absorption in humans cannot be understood with an either/or approach. If you really want to understand modern human variability in lactose absorption, you must consider both biology and culture."

These scholars feel that biocultural interactions have been essential throughout the last 50,000 years of human evolution, shaping many aspects of our physiology, morphology and behavior. The challenge facing Klein, Durham and their colleague John Rick, also of the Anthropology Department, is to construct the foundation for a strong undergraduate and graduate curriculum in human biocultural evolution.

The new program in human biocultural evolution does not yet have the resources to support graduate-level training, Klein said. Forthcoming renovation of a building in the main Quad will provide the necessary laboratory facilities, and the Anthropology Department hopes to make two key additional appointments soon. Meanwhile, Klein said he is looking forward to working closely with undergraduates in both human biology and anthropology.

"I came here twice in the past three years to teach the human origins portion of the human biology core class and was impressed both with that program and the students. My position in the Anthropology Department at Chicago made it much harder to interact with undergraduates."

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