Featured Research

from universities, journals, and other organizations

Fuller picture of human expansion from Africa

Date:
October 22, 2012
Source:
Stanford University
Summary:
A comprehensive analysis of the anthropological and genetic history of humans' expansion out of Africa could lead to medical advances.

A new, comprehensive review of humans' anthropological and genetic records gives the most up-to-date story of the "Out of Africa" expansion that occurred about 45,000 to 60,000 years ago. This expansion had a dramatic effect on human genetic diversity, which persists in present-day populations.
Credit: © Doreen Salcher / Fotolia

A new, comprehensive review of humans' anthropological and genetic records gives the most up-to-date story of the "Out of Africa" expansion that occurred about 45,000 to 60,000 years ago.

Related Articles


This expansion, detailed by three Stanford geneticists, had a dramatic effect on human genetic diversity, which persists in present-day populations. As a small group of modern humans migrated out of Africa into Eurasia and the Americas, their genetic diversity was substantially reduced.

In studying these migrations, genomic projects haven't fully taken into account the rich archaeological and anthropological data available, and vice versa. This review integrates both sides of the story and provides a foundation that could lead to better understanding of ancient humans and, possibly, genomic and medical advances.

"People are doing amazing genome sequencing, but they don't always understand human demographic history" that can help inform an investigation, said review co-author Brenna Henn, a postdoctoral fellow in genetics at the Stanford School of Medicine who has a PhD in anthropology from Stanford. "We wanted to write this as a primer on pre-human history for people who are not anthropologists."

This model of the Out of Africa expansion provides the framework for testing other anthropological and genetic models, Henn said, and will allow researchers to constrain various parameters on computer simulations, which will ultimately improve their accuracy.

"The basic notion is that all of these disciplines have to be considered simultaneously when thinking about movements of ancient populations," said Marcus Feldman, a professor of biology at Stanford andthe senior author of the paper. "What we're proposing is a story that has potential to explain any of the fossil record that subsequently becomes available, and to be able to tell what was the size of the population in that place at that time."

The anthropological information can inform geneticists when they investigate certain genetic changes that emerge over time. For example, geneticists have found that genes for lactose intolerance and gluten sensitivity began to emerge in populations expanding into Europe around 10,000 years ago.

The anthropological record helps explain this: It was around this time that humans embraced agriculture, including milk and wheat production. The populations that prospered -- and thus those who survived to pass on these mutations -- were those who embraced these unnatural food sources. This, said Feldman, is an example of how human movements drove a new form of natural selection.

Populations that expand from a small founding group can also exhibit reduced genetic diversity -- known as a "bottleneck" -- a classic example being the Ashkenazi Jewish population, which has a fairly large number of genetic diseases that can be attributed to its small number of founders. When this small group moved from the Rhineland to Eastern Europe, reproduction occurred mainly within the group, eventually leading to situations in which mothers and fathers were related. This meant that offspring often received the same deleterious gene from each parent and, as this process continued, ultimately resulted in a population in which certain diseases and cancers are more prevalent.

"If you know something about the demographic history of populations, you may be able to learn something about the reasons why a group today has a certain genetic abnormality -- either good or bad," Feldman said. "That's one of the reasons why in our work we focus on the importance of migration and history of mixing in human populations. It helps you assess the kinds of things you might be looking for in a first clinical assessment. It doesn't have the immediacy of prescribing chemotherapy -- it's a more general look at what's the status of human variability in DNA, and how might that inform a clinician."

The study is published in the current edition of the Proceedings of the National Academy of Sciences and was co-authored by Feldman's longtime collaborator, population geneticist Luigi Luca Cavalli-Sforza of Stanford and the Universitΰ Vita-Salute San Raffaele in Italy.


Story Source:

The above story is based on materials provided by Stanford University. The original article was written by Bjorn Carey. Note: Materials may be edited for content and length.


Journal Reference:

  1. B. M. Henn, L. L. Cavalli-Sforza, M. W. Feldman. The great human expansion. Proceedings of the National Academy of Sciences, 2012; DOI: 10.1073/pnas.1212380109

Cite This Page:

Stanford University. "Fuller picture of human expansion from Africa." ScienceDaily. ScienceDaily, 22 October 2012. <www.sciencedaily.com/releases/2012/10/121022145445.htm>.
Stanford University. (2012, October 22). Fuller picture of human expansion from Africa. ScienceDaily. Retrieved November 22, 2014 from www.sciencedaily.com/releases/2012/10/121022145445.htm
Stanford University. "Fuller picture of human expansion from Africa." ScienceDaily. www.sciencedaily.com/releases/2012/10/121022145445.htm (accessed November 22, 2014).

Share This


More From ScienceDaily



More Fossils & Ruins News

Saturday, November 22, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Amphipolis Tomb Architraves Reveal Faces

Amphipolis Tomb Architraves Reveal Faces

AFP (Nov. 22, 2014) — Faces in an area of mosaics is the latest find by archaeologists at a recently discovered tomb dating back to fourth century BC and the time of Alexander the Great in Greece. Duration: 01:05 Video provided by AFP
Powered by NewsLook.com
US Returns Looted Artifacts to Thailand

US Returns Looted Artifacts to Thailand

AFP (Nov. 19, 2014) — The United States has returns over 500 vases, bowls, axes, and other ancient artifacts mostly from the Ban Chiang archaeological site which were illegally looted from Thailand decades ago. Duration: 01:13 Video provided by AFP
Powered by NewsLook.com
How To Search Through Every Public Tweet Sent Since 2006

How To Search Through Every Public Tweet Sent Since 2006

Newsy (Nov. 19, 2014) — Twitter has announced improvements to its search index that allow users to search through every public tweet sent since its inception in 2006. Video provided by Newsy
Powered by NewsLook.com
Professor Unlocks the Mystery of Paintings

Professor Unlocks the Mystery of Paintings

AP (Nov. 19, 2014) — Richard Johnson, a computer and engineering professor at Cornell University, is using technology to uncover mysteries about the age and authenticity of historic paintings by artists like Johannes Vermeer and Vincent Van Gogh. (Nov. 19) Video provided by AP
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:

Strange & Offbeat Stories

 

Plants & Animals

Earth & Climate

Fossils & Ruins

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