|Vol. 20, No. 19||October 15, 1998|
Genetic Findings Support 'Out of Africa' Theory
A recently published genetic study involving 28 Chinese populations found evidence to suggest modern Chinese people descended from a common African ancestor, which supports the theory that modern man migrated out of Africa.
Some anthropologists have challenged the 'Out of Africa' theory and believe human fossil remains unearthed in China indicate that the modern Chinese Man originated independently.
University of Texas-Houston geneticist Li Jin, who spearheaded the genetic study, said, "By analyzing the data, you can clearly see the majority of the gene pools in China were from Africa. We could not find any evidence that is consistent with the hypothesis of independent origin in China.
"This study still does not exclude the fact that there could have been independent origin. But it shifts the burden of proof to those who believe in that theory," he added.
The five-year collaborative effort between Dr. Jin, an assistant professor at The University of Texas-Houston Genetics Center at the School of Public Health, and 12 other researchers based in China also confirmed genetic differences between northern and southern Chinese populations. China contains 56 official ethnic groups, with up to 200 languages spoken.
According to Dr. Jin, the northern populations can be broken down into two subgroups, one of which resembles populations in southern China. This raises the theory that some northern groups may be a subset of the southern Chinese.
The research supports the hypothesis that both northern and southern populations entered China 50,000 to 60,000 years ago from Southeast Asia and then moved north. Some members of this group continued even further north, overcoming the geographic barrier that separates North and South China, and populated parts of northern China.
Dr. Jin stressed that genetic differences among individual human beings account for up to 85 percent of the entire genetic spectrum, while the genetic differences in the world population are only about 15 percent. "No matter which ethnic group you come from, we're all pretty much the same."
The study's findings will have an impact on the way in which Chinese populations are selected for research, said Dr. Jin. Information about the genetic makeup of the Chinese populations will allow researchers to select certain groups when studying such complex diseases as diabetes and hypertension.
Dr. Jin and his collaborators used microsatellites, a set of genetic markers, to study the genetic relationships between the Chinese populations. Microsatellites are short stretches of DNA that have high mutation rates and occur in large numbers within the human genome. "These markers are extremely informative compared with classical markers," said Dr. Jin.
The study's results appeared in the September 29 issue of the Proceedings of the National Academy of Sciences. Funding for the project came from the National Natural Sciences Foundation of China.
- KRISTINA VAN ARSDEL, LISA GARVIN
©2006 Texas Medical Center