Featured Research

from universities, journals, and other organizations

Genetic Evidence Used To Trace Ancient African Migration

Date:
August 5, 2008
Source:
Stanford University Medical Center
Summary:
Researchers peering at history's footprints on human DNA have found new evidence for how prehistoric people shared knowledge that advanced civilization.

Researchers have found that animal-herding methods arrived in southern Africa 2,000 years ago on a wave of human migration, rather than by movement of ideas between neighbors.
Credit: iStockphoto/Michel De Nijs

Stanford University researchers peering at history's footprints on human DNA have found new evidence for how prehistoric people shared knowledge that advanced civilization.

Using a genetic technique pioneered at Stanford, the team found that animal-herding methods arrived in southern Africa 2,000 years ago on a wave of human migration, rather than by movement of ideas between neighbors. The findings shed light on how early cultures interacted with each other and how societies learned to adopt advances.

"There's a tradition in archaeology of saying people don't move very much; they just transfer ideas through space," said Joanna Mountain, PhD, consulting assistant professor of anthropology. Mountain and Peter Underhill, PhD, senior research scientist in genetics at Stanford's School of Medicine, were the study's senior authors. Their findings will appear in the Aug. 5 advance online edition of Proceedings of the National Academy of Science.

"We know that humans had to migrate at some point in their history, but we also know humans tend to stay put once they get someplace," Underhill said.

Instead of using archaeological evidence alone to guess whether people migrated, "all of a sudden, with genetics, you can actually address that question," Mountain said.

The researchers tracked genetic variation on the Y chromosome, the sex chromosome passed from father to son that encodes maleness, using a technique now widely used that was developed in the early 1990s by Underhill and colleagues in the lab of Luigi Cavalli-Sforza, professor emeritus of genetics. The method has given scientists a powerful window into ancient human migrations and prehistoric cultural shifts. The technique has also been adopted by some commercial genealogy services that offer Y-chromosome testing to the public.

Previous research suggested that prehistoric people in eastern and southern Africa had little contact, with only two known migrations between the regions about 30,000 and 1,500 years ago. After Bantu-language speakers migrated from eastern to southern Africa 1,500 years ago, agriculture took off in southern Africa. But the timing of the Bantu migration didn't quite match the 2,000-year-old anthropological evidence for the first sheep and cattle herds in southern Africa, so anthropologists were unsure whether the region's agricultural knowledge came from a bow-wave of ideas that spread in front of the migrating Bantu, or whether a separate migration brought the first herders.

"Africa has the most genetic diversity in the world, but it is one of the least-studied places," said Brenna Henn, a doctoral student in anthropology who was the study's lead author. "I've always felt like there were a lot of stories there that nobody's had the time or interest to look into."

The Stanford scientists picked the Y sex chromosome to examine for clues to migration because it changes very little from one generation to the next. Autosomes - the non-sex chromosomes - come in pairs, and the members of a pair can exchange bits of DNA during reproduction, making each autosome a mishmash of DNA from all of an individual's ancestors. But the Y chromosome is a singleton; males inherit one Y chromosome and one X chromosome, while women have two X chromosomes. In men, only a tiny region of the Y chromosome can swap DNA with the X chromosome. This means almost all of the Y chromosome moves intact from father to son, changing only infrequently when a new mutation arises. That allows researchers to examine several generations of ancestry by looking at the Y chromosomes of living men.

"The family tree of the Y chromosome is very, very clear," Mountain said.

The team analyzed Y chromosomes from men in 13 populations in Tanzania in eastern Africa and in the Namibia-Botswana-Angola border region of southern Africa. They discovered a novel mutation shared by some men in both locations, which implied those men had a common ancestor. Further analysis showed the novel mutation arose in eastern Africa about 10,000 years ago and was carried by migration to southern Africa about 2,000 years ago. The mutation was not found in Bantu-speakers, suggesting that a different group - Nilotic-language speakers - first brought herds of animals to southern Africa before the Bantu migration.

This new genetic evidence correlates well with pottery, rock art and animal remains that suggest pastoralists - herders who migrated to new pasture with their flocks - first tended sheep and cattle in southern Africa around 2,000 years ago. The genetic finding also helps explain linguistic similarities between peoples in the two regions.

"I like the fact that the linguistic, genetic and archaeological evidence all line up," Henn said. "When you see lines of evidence converge on a single model, it means that's probably something that actually happened."

Underhill and Roy King, MD, PhD, associate professor of psychiatry and behavioral sciences, published a similar paper in the June issue of the journal Antiquity. That study used Y chromosome evidence to examine how climate change drove prehistoric migration in the Middle East. They found that a shift in rainfall 10,000 years ago propelled a cultural split among genetically related people. Some stayed in rainy areas and grew crops, while others moved to arid regions and lived the nomadic life of pastoralist herders. The groups didn't intermingle much after the split, perhaps explaining the origins of modern Middle Eastern cultures.

Genetic evidence gives a degree of clarity to the study of prehistoric migration that's hard to achieve in other ways.

"So rarely do we get to pin down the questions raised by archaeology," Mountain said.

Henn, Mountain and Underhill collaborated with scientists at the Stanford Genome Technology Center; the University of Regensburg, in Germany; Sapienza Università di Roma, in Italy, and the University of Maryland.

The research was supported by grants from the National Science Foundation, the National Institutes of Health, the Wenner-Gren Foundation, the Leakey Foundation and BayGene (the Bavarian Genome Network).


Story Source:

The above story is based on materials provided by Stanford University Medical Center. Note: Materials may be edited for content and length.


Cite This Page:

Stanford University Medical Center. "Genetic Evidence Used To Trace Ancient African Migration." ScienceDaily. ScienceDaily, 5 August 2008. <www.sciencedaily.com/releases/2008/08/080804190635.htm>.
Stanford University Medical Center. (2008, August 5). Genetic Evidence Used To Trace Ancient African Migration. ScienceDaily. Retrieved September 2, 2014 from www.sciencedaily.com/releases/2008/08/080804190635.htm
Stanford University Medical Center. "Genetic Evidence Used To Trace Ancient African Migration." ScienceDaily. www.sciencedaily.com/releases/2008/08/080804190635.htm (accessed September 2, 2014).

Share This




More Fossils & Ruins News

Tuesday, September 2, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Did Neanderthals Play Tic-Tac-Toe?

Did Neanderthals Play Tic-Tac-Toe?

Newsy (Sep. 2, 2014) — Artwork found in a Gibraltar cave that was possibly done by Neanderthals suggests they may have been smarter than we all thought. Video provided by Newsy
Powered by NewsLook.com
Millions Of Historical Public Domain Photos Added To Flickr

Millions Of Historical Public Domain Photos Added To Flickr

Newsy (Aug. 30, 2014) — Historian Kalev Leetaru uploaded a large collection of historical photos, images that were previously difficult to collect. Video provided by Newsy
Powered by NewsLook.com
Minds Blown: Scientists Develop Fish That Walk On Land

Minds Blown: Scientists Develop Fish That Walk On Land

Newsy (Aug. 28, 2014) — Canadian scientists looking into the very first land animals took a fish out of water and forced it to walk. Video provided by Newsy
Powered by NewsLook.com
Huge Ancient Wine Cellar Found In Israel

Huge Ancient Wine Cellar Found In Israel

Newsy (Aug. 28, 2014) — An international team uncovered a large ancient wine celler that likely belonged to a Cannonite ruler. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins