DNA findings confirm "out of Africa" theories

BEIJING, Feb. 21 (Xinhuanet) -- Two genetic studies
confirm theories that modern humans evolved from Africa and then migrated
through Middle East to Europe and Asia and finally reached the Pacific and
Americas,according totheNature Thursday.

One studylooked at more than 500,000 genetic
variations from 485 volunteers in 29 different groups from Africa, Europe, the
Middle East, Southeast Asia, the Pacific Ocean islands and the Americas.

It found that people of African descent are the
most genetically diverse, followed by people from the Middle East, and then
Asians and Europeans. Native Americans resemble one another the most on a DNA
level.

The closer populations are, the greater the
degree of similarity between the populations, said Noah Rosenberg, co-senior author ofthe
study.

"This suggests that a genetic
history reflects a history in which populations migrated out of Africa, and
along the way only a portion of the genetic diversity available migrated to the
next location," he said.

Diversity has been eroded through the migration
process.

In another study, Carlos Bustamante, an assistant
professor of biological statistics and computational biology at Cornell
University, looked at 10,000 genes in 15 black Americans and 20
European-Americans, all of whom were healthy.

"Across all the individuals, we found almost
40,000 DNA sites that varied. The African-American sample more variations
than the European-American sample, which is consistent with previous work
showing higher levels of overall genetic diversity in African-Americans,"
Bustamante said.

They studiesreinforce the idea that humans
originated in Africa, then spread into the Middle East, followed by Europe and
Asia, the Pacific Islands and finally to the Americas.

However, the genes do not indicate the diverse genes
are better than the more stable ones, or vice versa.

"The one thing that I think we cannot say from this
study is that any one person's genome is any healthier or evolutionarily fit
than another person's genome," said Bustamante.

(Agencies)