Vast language, gene study unveils our history ROOTS OF HUMANITY

American scientists working with colleagues in six African nations and Europe have been boldly tracing the genetic roots of all humanity for the past 10 years, and their first results have just started coming in.

The effort - the most ambitious of its kind ever undertaken - is an attempt to learn in detail how remarkably diverse humans are; how our varied genes make some of us susceptible to deadly diseases and some immune; and just where in Africa our human ancestors first moved out of the continent more than 50,000 years ago to populate the world.

The researchers examined the genes and historical linguistics among thousands of remote African tribal peoples, carrying on a long and once-controversial study begun more than 50 years ago by Stanford geneticist Luigi Luca Cavalli-Sforza and continuing today in partnership with Stanford mathematician Marcus Feldman.

Geneticist Sarah A. Tishkoff of the University of Pennsylvania is leading the latest project with support from African researchers in Cameroon, Mali, Tanzania, Kenya, Nigeria and Sudan. The first results were reported Thursday in the online journal Science Express.

Over the past decade, the researchers analyzed the genes and languages of more than 3,000 people in 121 population groups across the most isolated regions of Africa, plus 60 in Europe, and four groups of African Americans in various states across the United States. All of the participants volunteered blood samples for gene analysis, the scientists said.

Tishkoff's team also combined clues from the most ancient languages of Africa with their knowledge of the 2,000 languages now spoken on that continent. The scientists also examined the genomes of all the individuals they studied, and from all of that drew a picture of historic migration patterns among the many African population groups, linking them to the origins of African Americans in greater detail than ever before.

New insights into Africa

One of Tishkoff's colleagues, Dr. Muntaser Ibrahim, a molecular biologist at the University of Khartoum's Institute of Endemic Disease in Sudan, said in a phone interview from Khartoum that the project has revealed "spectacular insights into the history of African populations and indeed the origins of all mankind."

Because such projects in the past required drawing blood samples from so many thousands of African hunter-gatherers in isolated tribes, some scientists had branded them as unethical. But Ibrahim said that won't be an issue this time.

"These remote people are unique genetically, and they have been very, very cooperative because they too would like to know about their past," he said. "The notion that these remote people are not interested in genetics is not at all true."

Christopher Ehret, a noted specialist in African historical linguistics at UCLA and a member of Tishkoff's team, said his analysis of tribal languages revealed striking patterns of migration across Africa.

"When people move, they borrow words from the people where they settle," he said. Those new words inserted into older languages, he said, can tell us when the newcomers arrived.

For example, Ehret said, the "click" language still spoken among people as varied as the San of South Africa, the Pygmy tribes of Central and West Africa and the Hadze people far to the east may well be the original spoken language of all humans - and the genes of those distant click speakers indicate they share a common ancestry, the scientists noted.

Scott M. Williams of Vanderbilt University, who searched for disease-causing genes among the most remote African populations, said he found genetic evidence of ancient susceptibility to disorders as varied as hypertension, prostate cancer and the lactose intolerance that is common today both among African Americans and other American ethnic groups.

The ancient migration patterns that the scientists followed indicated to them that the very first true humans must have emerged on the evolutionary scene nearly 200,000 years ago somewhere in southern Africa, near where Namibia is now, Tishkoff said.

And while most of today's African American ancestors originated from West Africa during the infamous slave trade, Ehret and Tishkoff found strong evidence that many of those West African people came from groups that had migrated from the continent's eastern areas.

Stanford project led way

Stanford's Cavalli-Sforza and Feldman spent decades on what they called their Human Genome Diversity Project, and it continues today at Stanford's Morrison Institute.

The two Stanford leaders "paved the way for scientists like myself," said Tishkoff.

"They were the first to characterize global patterns of genetic variation and to show correlations between genetic and linguistic evolution," she said. "This is just the beginning of even more detailed studies of genetic variation in African and African American populations."

In a telephone interview from Italy on Thursday, Feldman said the new report "reinforces in a strong way the tremendous diversity and variability of population groups in Africa."

And the Tishkoff team's finding of such varied historical migration patterns in West Africa surely means any attempt by African Americans to learn the true origin of their earliest ancestors in Africa will be difficult, Feldman said.