The pieces are infinitesimal, the puzzle as big as history itself. And scientists are ready to solve it--to mount a worldwide gene hunt, from Africa's jungles to remote Pacific islands, to finally trace the story of man.
If only man would cooperate.
Under the ambitious plan, called the Human Genome Diversity Project, researchers would compare genes from hundreds of ethnic groups in order to map relationships, track prehistoric human migrations and perhaps make medical discoveries.
But American Indians, Australian aborigines and other indigenous groups have mobilized against the proposal, suspicious of commercial exploitation, worried that findings might undermine land claims and troubled by scary scenarios--the suggestion, for example, that someone could use their DNA to customize biological weapons to turn against them.
"What we're looking at are the most vulnerable people becoming victimized by science and commercial interests," said Debra Harry, a Nevada Indian activist.
The opposition has had an impact. In Paris, UNESCO has shied away from endorsing the project. In Washington, agencies that might underwrite the $5-million-a-year cost are wary.
"No major funds have been committed to it because of the controversy that arose," said Amar Bhat of the National Institutes of Health.
The controversy now rests with a 16-member committee at the U.S. National Academy of Sciences. The group will meet periodically in the coming months before reporting on the plan's scientific value and ethical safeguards.
The Diversity Project differs from the better-known Human Genome Project, the huge endeavor that regularly makes headlines by finding links between diseases and genes--those inherited bits of DNA in our cells whose chemical code determines each body's characteristics.
One by one, 100,000 or so genes, collectively known as the human genome, are being blueprinted by the $200-million-a-year "HGP." But everyone's genome is minutely different from everyone else's, so scientists are developing only a composite of broadly shared DNA, using samples from a handful of North Americans and Europeans.
The Diversity Project, on the other hand, would focus on the minute differences and reach out to every corner of the globe.
The plan, conceived by international geneticists led by Stanford University's Luigi Luca Cavalli-Sforza, would coordinate independent gene-sampling projects already underway.
Organizers say it will take at least five years to collect blood or other DNA samples from perhaps 500 ethnic groups, with a focus on isolated populations.
Because a New Guinea forest tribe, for example, has few, if any, outsiders' variant genes in its makeup, tribe members have relatively consistent genomes--making them easier to compare to other groups in search of patterns.
Patterns would enable geneticists to find family ties between groups--to reconstruct human genealogy. That could help answer a key question of anthropology: Did modern man evolve in Africa and then migrate; did he evolve on other continents too?
Geneticists also hold out the prospect that they may discover clues to disease susceptibility or immunity. "We firmly believe this project could be one of the most important scientific efforts of its era," Cavalli-Sforza said.
Mark Weiss, program director for physical anthropology at the National Science Foundation in Washington, described the project as "a splendid opportunity . . . to gain tremendous insight into human population history, human adaptation, biomedical questions."
But only "if it is done properly, after due judgment."
After the project was organized in 1993, the Canada-based World Council of Indigenous People quickly reached its judgment. "We . . . categorically reject and condemn the Human Genome Diversity Project," it declared.
Indigenous groups said outsiders were viewing them merely as a scientific resource, when they would prefer outsiders' help in preserving their cultures.
Council spokesman Rodrigo Contreras said scientists seemed to assume that "indigenous people are going to disappear in the immediate future and their cells are going to be studied in perpetuity."
Native groups also worry that genetic findings about a tribe's history might devastate traditional beliefs about its origins or undermine claims to "ancestral" lands. And some believe biotechnology companies will patent and profit from project discoveries without benefiting the source group.
Presenting their case last fall at the U.N. Educational, Scientific and Cultural Organization, indigenous representatives said that uneducated tribes cannot give truly informed consent to such scientific work.
"How can you expect that throughout the world people really understand what they are giving their consent on?" UNESCO's George Kutukdjian asked in a telephone interview from Paris.
His International Bioethics Committee has not decided whether to grant the Diversity Project's request for UNESCO oversight.
Project organizers say their ethical guidelines will address the objections, requiring extensive work to inform and obtain the consent of individuals and groups for gene sampling, and giving sampled populations veto power over the commercial use of genetic information.
A positive assessment by the National Academy could help chances for funding, but even if the project stalls, independent researchers will continue sampling genes among consenting populations worldwide.
"Ultimately," American Indian activist Harry said, "it will be a choice to be made by every indigenous nation."