By Paul Rincon
BBC News science reporter
A project spanning five continents is aiming to map the history of human migration via DNA.
Scientists aim to trace ancient human migratory routes (Image: Chris Johns/National Geographic)
The Genographic Project will collect DNA samples from over 100,000 people worldwide to help piece together a picture of how the Earth was colonised.
Samples gathered from indigenous people and the general public will be subjected to lab and computer analysis to extract the valuable genetic data.
Team leader Dr Spencer Wells calls the plan "the Moon shot of anthropology".
The $40m (£21m) privately funded initiative is a collaboration between National Geographic, IBM and the Waitt Family Foundation charity.
Participating in the five-year study are some of the world's top population geneticists, as well as leading experts in the fields of ancient DNA, linguistics and archaeology.
"We see this as a resource for humanity going into the future. It could potentially become the largest genetic database ever created," Dr Wells told the BBC News website.
Members of the public will be able to buy a kit that contains all the material needed to add their genetic information to the database.
Already, evidence from genetics and archaeology places the origin of modern humans (Homo sapiens) in Africa roughly 200,000 years ago.
It is thought, the first moderns to leave the continent set off around 60,000 years ago.
By studying the Y (or male) chromosome and mitochondrial DNA (which is passed down exclusively on the maternal line), scientists have pieced together a broad-brush picture of which populations moved where in the world - and when.
What is lacking, says Wells, is the fine detail, which could be filled in by this large-scale project.
"We know which markers on the Y chromosome to focus on; we know our way around the mitochondrial genome fairly well. We just haven't had the large sample sizes to apply these technologies properly," Dr Wells explained.
"There are still many questions we haven't answered. Was there any interbreeding with Neanderthals as modern humans moved into Europe? Did any of the migrations to the Americas come across the Pacific - or even the Atlantic?"
These and other unanswered questions form the research goals of the project. They include:
A total of 10 DNA collection centres located around the world will focus on obtaining samples from indigenous peoples. The genetic markers in the blood of these groups have remained relatively unchanged for generations.
- Who are the oldest populations in Africa - and therefore the world?
- Did Alexander the Great's armies leave a genetic trail?
- Who were the first people to colonise India?
- Is it possible to obtain intact DNA from the remains of Homo erectus and other extinct hominids?
- How has colonialism affected genetic patterns in Africa?
- Was there any admixture with Homo erectus as modern humans spread throughout South-East Asia?
- Is there any relationship between Australian Aboriginal genetic patterns and their oral histories?
- What are the origins of differences between human groups?
"Sub-Saharan Africa harbours the spectrum of variation that will allow us to trace the very origin of our species as well as more recent incursions," said Himla Soodyall, principal project investigator for that region.
But some researchers said experience on other projects suggested this one could run into trouble with indigenous groups - particularly those, such as Native Americans and Aboriginal Australians, with a history of exploitation.
"I don't know how they'll deal with getting samples from more sensitive places," commented François Balloux, a population geneticist at the University of Cambridge, UK.
"Amongst Australian Aborigines and Native Americans, the cultural resistance to co-operating with scientists is very strong.
Spencer Wells aims to build the world's largest genetic database ( Image: Mark Read)
"For example, many Native American communities are strongly advised by their elders not to give samples."
Ajay Royyuru, IBM's lead scientist on the Genographic Project was optimistic on the issue.
"We want to attract their participation by being extremely clear about what we do and do not do. For example, we are very clear about not trying to exploit their genetic diversity for medical uses," he told the BBC News website.
Project directors said they had already sought advice from indigenous leaders about their participation.
IBM says it will use sophisticated analytical techniques to interpret the information in the biobank and find patterns in the genetic data. The IT giant will also provide the computing infrastructure for the project.
The project will shed light on the origins of human diversity (Image: Jodi Cobb/National Geographic)
Kits sold to the public contain cheek swabs used to scrape the inside of the mouth for a DNA sample. The swabs can then be mailed to a central laboratory for analysis.
After four to six weeks, the results of the analysis will appear on the website behind an anonymous password contained in the kit.
The exact budget available for the study will depend on how many test kits are sold to the public. The net proceeds will go back into the research and into a "legacy project" to support indigenous peoples.
The Genographic Project's directors emphasise that the information in the database will be made accessible to scientists studying human migrations.
"We see this as part of the commons of our species. We're not going to be patenting anything - the information will all be in the public domain," said Dr Wells.
HUMAN MIGRATION ROUTES
Map shows first migratory routes taken by humans, based on surveys of different types of the male Y chromosome. "Adam" represents the common ancestor from which all Y chromosomes descended
Research based on DNA testing of 10,000 people from indigenous populations around the world
Source: The Genographic Project