It was a very triumphant moment for the young scientist. He was up for tenure and his work was being featured in back-to-back articles in the country's most prestigious science journal. Yet today, Dr. Lahn says he is moving away from the research. The reason why? "It's getting too controversial," he says.



Dr. Lahn has touched a nerve in science, race and intelligence.

Dr. Lahn told his audience that genetic changes over the past several thousand years may be linked to brain size and intelligence. He flashed maps that showed the changes had taken hold and spread widely in Europe, Asia and the Americas, but weren't as common in sub-Saharan Africa.

Web sites and magazines promoting white "racialism" quickly seized on Dr. Lahn's scientific snapshot. One magazine that blames black and Hispanic people for social ills hailed his discovery as "the moment the antiracists and egalitarians have dreaded."

Dr. Lahn has drawn criticism from other leading genetics researchers. They say the genetic differences he found may not signify any recent evolution, and even if they do, it is too big of a leap to suggest any link to intelligence. "This is definately not the place you want to report a weak association that may or may not stand up," says Francis Collins, director of the genome program at the National Institutes of Health.

Several scientific groups have set out to disprove Dr. Lahn's discoveries. His own university now says it is abandoning a patent application it filed to cover a DNA-based intelligence test that drew on his work.

As scientific tools for probing genes become increasingly more powerful, research into human differences has definately exploded. Most of the time, scientists are searching for clues about the causes of disease. But some research is raising tensions as scientists such as Dr. Lahn venture into studies of genetic differences in behavior or intelligence.

Pilar Ossorio, a professor of law and medical ethics at the University of Wisconsin, criticizes Dr. Lahn for implying a result similar to "The Bell Curve," a controversial 1994 bestseller by Richard J. Herrnstein and Charles Murray. The book argued that the lower average performance by African-Americans on IQ tests had a genetic component and wasn't solely the result of social factors. Referring to Dr. Lahn and his co-authors, Prof. Ossorio says: "It's exactly what they were getting at. There was a lot of hallway talk. People said he's doing damage to the whole field of genetics."

The 37-year-old Dr. Lahn says his research papers, published in Science last September, offered no view on race and intelligence. He personally believes it is possible that some populations will have more advantageous intelligence genes than others. And he thinks that "society will have to grapple with some very difficult facts" as scientific data accumulate. Yet Dr. Lahn, who left China after participating in prodemocracy protests, says intellectual "police" in the U.S. make such questions difficult to pursue.

Scientists believe that a small group of anatomically modern humans struck out from Africa probably less than 100,000 years ago. After arriving on the Eurasian land mass, they continued to split up and eventually humans populated nearly every corner of the globe. One use of genetic research is to probe how each group evolved differently after becoming isolated from the others. Recently created genetic maps of people of African, Asian and European ancestry make that research easier.

Other research is starting to explain variations in human skin color and hair texture. But scientists tense up when it comes to doing the same sort of research on the brain. Sociologist Troy Duster, who studies the use of racial categories by geneticists, worries that scientists will interpret data in ways that fit their prejudices. He cites the sorry history of phrenology, a study of skull shapes popular in the 19th century, and other pseudoscientific techniques used to

categorize people as inferior. "Science doesn't transcend the social milieu," says Dr. Duster, of New York University.

The fellowship pays most of his research bills and has allowed him to pursue creative projects, often on attention-grabbing subjects. One study looked at how promiscuity among female chimpanzees, gorillas and humans affected the evolution of a gene that makes sperm sticky. "Bruce is in a hurry to be famous," says Martin Kreitman, a Chicago colleague who is friendly with him.

Henry Harpending, a University of Utah anthropology professor who recently published a theory for why Ashkenazi Jews tend to have high IQ's, says Dr. Lahn once suggested they co-author an article for Scientific American about the genetics of behavior, in which they could explain why "Chinese are boring."