Indigenous people around the world will be asked to supply a cheek swab to help geneticists answer the question of how humanity spread from Africa.
The National Geographic Society and IBM hope to sample 100,000 people or more and look for ancient clues buried in living DNA to calculate who came from where and when.
For $US100, anyone who wants to can supply his or her own cheek swab for a personalised analysis and perhaps to contribute to the research.
Geneticist and anthropologist Spencer Wells said: "We all came out of Africa but how did we get to where we are today? What we are aiming for is the story of everybody."
Experts in related fields such as population genetics, archaeology, evolution science, linguistics and palaeontology will help in the five-year project.
Fossils provide some clues about where people settled as they evolved and moved from Africa to colonise every continent except Antarctica.
But mysteries remain, for example, about how people first got to Australia 50,000 to 60,000 years ago, or when and from where the first humans arrived in the Americas.
Linguistics and DNA provide many clues but the so-called Genographic Project will aim to systematically look at all peoples on all continents.
Teams in China, Russia, India, Lebanon, Brazil, South Africa, Paris, Britain and Australia have signed on to help.
Mr Wells says some groups may be hostile to the effort. "There has been a history of exploitation of indigenous groups around the world," he said.
But, he added, experts on dealing with various groups will help sell the idea. "It's a question of explaining the science," he said.
Geneticists will look at little changes in DNA code that have been used by experts to trace human history.
Mitochondrial DNA, handed down virtually unchanged from mothers to their children, is one source that was used to calculate the so-called ancestral Eve, who would have lived in Africa about 180,000 years ago.
Men have their own version, found in the Y chromosome, which is inherited with very little change from father to son.
Tiny mistakes in the code that occur with each generation can be used as a kind of genetic clock to track backward.
People who buy the mail-in swab kit are unlikely to add to the indigenous people's database but can find out something about their own ancient ancestry and perhaps add to the effort, Mr Wells said.