Of course, giving groups the right to consent means that some will decline. "That's fine," Greely says. "We're under no illusion that we're going to get samples of every human population. Our goal is to get just five percent—so nineteen of twenty could not participate."
How Different Are We?
RAFI's efforts to derail the Human Genome Diversity Project can be seen as a noble attempt to protect the powerless. They can also be seen as tragically misguided. If activists succeed in fomenting widespread distrust of genetics research, they could ruin an opportunity to discredit the essential notion underlying racism—that human groups have innate and fundamental biological differences.
This idea has deep roots. In 1758 the Swedish botanist Carolus Linnaeus gave the human species its formal name, Homo sapiens. He also divided the species into subcategories: red Americans, yellow Asians, black Africans, and white Europeans. He described Homo sapiens americanus as "ill-tempered, ... obstinate, contented, free." Homo sapiens asiaticus was "severe, haughty, desirous." Homo sapiens afer was "crafty, slow, foolish." And Homo sapiens europaeus was—of course—"active, very smart, inventive."
Similar prejudices characterized biological thinking well into the twentieth century. From 1910 to 1930 most of the leading human geneticists in the United States actively supported the campaigns of eugenicists to limit reproduction by those deemed biologically inferior, including Eastern Europeans, Jews, and people with mental disabilities. This line of thinking led directly to the gas chambers of Nazi Germany, which effectively ended the eugenics movement. Yet the basic tenet of eugenic thinking—that the mental attributes of human groups differ for genetic reasons—remains firmly embedded in the popular imagination.
Until very recently most geneticists professed agnosticism on this issue. They said that not enough was known to assess the contributions of genetics to behavioral differences among groups. The data collected by Cavalli-Sforza and other population geneticists have been making that position less and less tenable. People are too closely related—and have mixed too much throughout history—to differ in fundamental ways.
Interpretations of this research have been controversial in the past, but the genetic evidence is now overwhelming. It clearly indicates that sometime in the period 100,000 to 200,000 years ago our ancestors went through a severe genetic bottleneck. Perhaps an environmental change drove ancient people to the brink of extinction. A more likely scenario, however, is that a relatively small group, numbering fewer than 20,000 at times and probably living in eastern Africa, was isolated for many thousands of years from the many groups of archaic human beings scattered throughout Africa, Europe, and Asia. The people who emerged from this genetic bottleneck had traits never before seen in human beings. They had lighter builds, new ways of interacting among themselves, and perhaps a greater facility with language. Eventually the descendants of these people spread throughout Africa and beyond. They reached Australia at least 60,000 years ago, probably traveling from the Horn of Africa and then along the South Asia shoreline. They arrived in the Middle East a bit more than 40,000 years ago. By 35,000 years ago anatomically modern people had spread into Europe from the Middle East and into East Asia from Southeast Asia. Sometime more than 12,000 years ago they entered the Americas.
Elsewhere on the Web
Links to related material on other Web sites. Evolution of Modern Humans: The Biological and Cultural Evolution of Archaic and Modern Homo sapiens
A site offering descriptions, charts, and timetables documenting the evolution of modern humans. Created by a professor at Palomar College, San Marcos, California. Whenever modern human beings came in contact with their archaic counterparts, the latter eventually disappeared. Many questions surround this process. The genetic evidence indicates that modern people bred very little with the archaic people living throughout the Old World. According to Joanna Mountain, a Stanford anthropologist who has been studying the genetics of African groups since the 1980s, when the Peace Corps took her to Kenya, "If the ancestral modern human population fifty thousand years ago had been highly diverse genetically, as it would have been if there had been a lot of mating with archaic peoples, we would still see evidence of that diversity today, but we don't." One possibility is that modern and archaic human beings did mate, but were so different genetically that such matings were infertile. Or maybe some matings between archaic and modern human beings did produce offspring, but at such a low rate that the archaic genes have been diluted out of existence.
How modern human beings replaced their predecessors also remains a mystery. Archaeological evidence indicates that bands of modern and archaic people sometimes lived near each other for thousands of years. Yet no remnants of warfare have been found. The cave paintings of Europe, some of which date from the period when modern people were replacing Neanderthals, evince plenty of violence against animals but not against other people.