The University Record, February 15, 1993

10 making presentations at AAAS

Ten U-M scholars are making presentations at the American Association for the Advancement of Science (AAAS) meeting that began Feb. 11 in Boston.

‘No cradle of modern humanity’

In a paper titled “Klasies River Mouth Cave: Modern Humans or Not?” anthropologists Rachel Caspari and Milford Wolpoff reinterpret the fossil evidence from one of the most important archaeological sites in Africa, offering new insights on a surprisingly intractable question: What does it mean to be a modern human?

The paper provides fresh support for a theory of multiregional evolution rather than a single-origin, Out-of-Africa theory. Their research weakens a major pillar of support for the so-called Eve theory—the idea that one African woman who lived about 200,000 years ago was the mother of the modern human race.

“The site in South Africa is one of the most examined and firmly dated in the field. The fossil remains there are generally assumed to be those of the earliest modern humans. But we believe the fossils are archaic rather than modern,” states Caspari, who will deliver the paper.

All the fossils date from the same time period, roughly 100,000 years ago, but not all have certain craniofacial features widely thought to be marks of modern man.

“The problem of defining what a modern human is reflects not only the wide range of modern human variation, but also the fact that there really is no discrete entity—anatomically modern Homo sapiens—with a distinct origin in any specific place,” Caspari says. “Simply put, we will never find the cradle of modern humanity—the birthplace of Eve—because a single source does not exist.

“To define what it means to be a modern human,” she concludes, “we need to look beyond anatomy to culture.”

ECHO sorts through complex adaptive systems

Many of our most troubling long-range problems—such as international trade, AIDS and genetic defects—center on systems of extraordinary complexity called complex adaptive systems (CAS). John Holland, professor of psychology and of electrical engineering and computer science, believes the behavior in all such systems is governed by one set of general principles. To identify these principles and study CAS interactions, he has developed ECHO, a computer simulation of complex adaptive systems.

“ECHO is based on simple interactions found in all complex adaptive systems,” Holland says, “and it provides a unified framework for studying the evolution of CAS. ECHO simulates a population of evolving, learning, reproducing agents distributed over an array of sites with different inputs of renewable resources at the site. The agents can be business firms, species in a ecosystem, antigens in the immune system, or mixtures of different types of agents,” he explains.

Holland is concentrating on identifying factors that encourage or discourage innovation by ECHO agents. He also is trying to understand the delicate balance between cooperation and competition that is the basis for interaction between agents in all complex adaptive systems.

Little Ice Age not a global event

The Little Ice Age—a period of increased precipitation and cooler temperatures in Western Europe that lasted from 1500 to 1850—also occurred in several other parts of the Northern Hemisphere, but not at the same time or with the same degree of cooling, says Henry N. Pollack, professor of geological sciences.

While borehole temperatures confirm cooling took place in Greenland, Alaska, France and Canada, they also show that “the Little Ice Age was not a globally uniform event in terms of onset, duration or amplitude,” says Pollack, who presented a summary of data from several independent investigators at the AAAS meeting.

Pollack is one of a handful of geologists using boreholes originally drilled for mineral exploration to study long-term climate changes.

Inbreeding less significant than thought

When first cousins marry, genetic abnormalities in their offspring are less significant than expected, according to James Neel, the Lee R. Dice Distinguished Professor Emeritus of Human Genetics and professor emeritus of internal medicine.

Analyzing data from postwar Japan, a society with a high rate of consanguineous marriages, Neel found only a 1.5 percent higher rate of mortality among the offspring of related parents than among the offspring of non-related parents. The same rate applied to major genetic defects.

Neel’s study shows only a slight dip in the intelligence curve, mathematical skills and language ability among both boys and girls born to cousins.

The children of cousins who marry have been of interest to geneticists for years. At the clinical level, Neel’s data on these offspring provide information to genetics counselors when the question of a cousin marriage arises. On a more theoretical level, the data provide rare information on the gene pool to population geneticists.

Other U-M participants in the meeting:

—Elliott Soloway, associate professor of electrical engineering and computer science, demonstrated a software package he developed for a notebook to be used by computational scientists.

—Randolph M. Nesse, professor of psychiatry, spoke on “Evolutionary Psychiatry.”

—Carol S. Hollenshead, Cinda-Sue Davis and Brian Coppola organized a symposium on “Women in Science, Engineering and Mathematics: Research and Institutional Change.” Hollenshead, director of the Center for the Education of Women (CEW), discussed “Climate for Graduate Women in Scientific Fields.” Coppola, lecturer in chemistry, discussed “How Will We Know Good Curricula When We See Them?” Davis heads CEW’s Women in Science Program.

Based on material provided by Sally Pobojewski, News and Information Services, and Cindy Fox Aisen, Medical Center Public Relations.