Every one of us is a melting pot of genetic lineages. Even so, the findings of our genome map have sent shockwaves through certain groups. Take the ancient trade route known as the Silk Road, which ran through Eastern Europe and Central Asia. Sampling blood from populations along the Silk Road, Wells uncovered a Y chromosome marker common among Mongolians but rare in central Asians. This means the twelfth- and thirteenth-century invasions of the Mongol armies of Ghenghis Khan left a strong cultural heritage, but not a genetic one; in other words, they were a small, elite group moving into a much larger population. They may have changed the course of history, but their genes did not prevail.

Other research into Jews known in Hebrew as kohanim—priests who are said to be direct descendents of Moses and Aaron—actually confirms the legend. A gene found in only about 3 percent of all male Jews shows up in about half of all self-declared kohanim. At the same time, Jews were shocked when scientists found the kohanim gene in a black, Christian tribe in South Africa and Zimbabwe named the Lemba—a tribe that believes its members are descended from Jews and that scholars have never taken seriously. In fact, in the tribe’s founding clan, 53 percent of males had the gene. In another surprise, Jewish males studied by an international team of scientists led by Michael Hammer of the University of Arizona in Tucson and Batsheva Bonne-Tamir of Tel Aviv University in Israel were shown to have Y-chromosomes that correlated highly not only with other Jews but also with Palestinian Arabs, Syrians, and Lebanese.

In one fell swoop, the genome map confirms apocryphal oral histories and yet binds groups that may consider themselves enemies. Even more striking, new studies are resurrecting the speculation that intelligence is heritable, and that it may be different in different groups. This kind of thinking began with Swedish botanist Carolus Linnaeus, who in 1758 divided humans into four races: red Americans, yellow Asians, black Africans, and white Europeans—each with different traits. It was a short skip and a hop to eugenics and the Nazi gas chambers. Recently these ideas were resurrected in the controversial bestseller The Bell Curve by Charles Murray and Richard Hernstein (Free Press, 1994), which proposed that IQ was inherited and “discovered” that IQs of black people were uniformly lower than those of Caucasians. The book relied in part on the work of geneticist Philippe Rushton, a professor at the University of Western Ontario in Canada.

“What most people seem to miss about The Bell Curve is that it followed twelve thousand youths for twelve years and found that IQ is the single best predictor of all kinds of life outcomes,” Rushton says. “But it was the fifteen IQ-point difference between blacks and whites that took all the attention. Nobody cared that East Asian and Jewish [students] scored much higher than whites.”

Rushton says the much-pilloried The Bell Curve didn’t go far enough. “It could have explained the differences in IQ scores by the differences in brain size,” he contends. “Black-white differences in brain size have been known reliably for 150 years. The attempt to abolish the concept of race is pure political correctness. If race was not a predictive variable, it would not be used.”

It’s enough to make your skin crawl—whatever color you happen to be. But what’s even more discomfiting is that some of the science backs up these differences. “The stuff he says makes you gag, but it’s right,” says the University of Utah’s Harpending. “I don’t teach it because I’m a coward. He publishes these abridged editions that are just right for the Ku Klux Klan. On the other hand, this correlation between brain size and intelligence has been there for years.”

A new study from the University of California-Los Angeles seems to confirm the evidence. UCLA researchers found that the amount of gray matter in the frontal parts of the brain is determined by the genetic makeup of an individual's parents, and it strongly correlates with that individual’s cognitive ability— as measured by IQ tests. Published in Nature Neuroscience in November, the research used specialized brain mapping, creating the first images ever linking genes and intelligence. “ 'We were stunned at the results,'” said assistant professor of neurology Paul Thompson, the study's chief investigator.

Group traits may be inherited as well. Softer but intriguing work from Harpending suggests that traits like impulsiveness and unpredictability may be regulated by the dopamine receptor known as D4. Specific mutations of genes are known as alleles, and according to Harpending, one allele puts people at a somewhat increased risk for Attention Deficit Hyperactivity Disorder. “There are big population differences around the world in that gene. It’s completely absent in China and in Bushmen. You find it in 40 percent of North American Indians, and 60 percent of South American Indians. We believe it does have an effect on behavior.”

The science itself is not the danger; it’s what we do with it. Fissionable atoms can’t hurt us, but atomic bombs can. According to Marks from the University of North Carolina, even non-racist and brilliant scientists like Cavalli-Sforza have difficulty eliminating the deeply embedded “Platonic” ideal of Linneaus’ four races. “Cavalli will gladly tell you there is no such thing as race,” Marks says, “but his genetic diversity map has four color-coded ethnic regions. He’s starting out with a fundamental fallacy that’s 250 years old. He’s reproduced race but called it ethnic regions. The fact is, we’re so accustomed to thinking about our world this way it seems entirely natural. But if we look at it very, very carefully, we will realize it is entirely arbitrary, and not natural at all.”

The genome map tells us two stories: Groups—and races—do pass on traits such as intelligence, robustness, impulsivity; and groups—and races—cannot be so easily separated because our diversity and our links are far more complex. But our culture tells another story, and its crimes are based in our biology, the ways our brains are hardwired—a different aspect of our genes.

Racism arises from our primate origins, according to Frans De Waal, director of the Living Links Center at Emory University in Atlanta, Georgia: “Outgroup hostility is very strongly developed in our species, like many others.” Just like birds, hyenas, chimps, and all other species, we compete for resources. “The basic reason for all animal territoriality is to defend the resources that are on it,” De Waal says. In addition, race segregation seems to occur in adolescence and to be linked to reproductive strategies. “It sure is striking,” Harpending says. “When The New York Times did its big series about race, it made that point. People lost their friends in puberty. Evolution leads me to propagate with somebody who looks like me, so I can pass on copies of DNA like mine.”

OK, but when a Muslim declares Jihad on an American citizen ten thousand miles away, territory and reproductive strategy seem unlikely motives.

“Race talk is as tricky as God talk,” says molecular geneticist Ursula Goodenough, a professor of biology at Washington University in St. Louis, Missouri, and author of The Sacred Depths of Nature (Oxford University Press, 1998). “Race is something you can see, and it’s important if only because of that. But there’s a difference between being aware of race and chasing it away.” Goodenough suggests racism is just one aspect of our primate-based fear of difference. “If you take a group of apes and introduce an ape they’re not familiar with, they gang up on him. My cats do it too. Lord have mercy on a strange cat that ventures into my yard. The core thing we fear is the unfamiliar. There was a group of day care kids in Iowa in a particular town with a lot of diversity—orphans from Vietnam and Thailand, black kids, white kids, Chinese. The kids all went to school together and never paid any attention to color. But then a kid came in with Down’s Syndrome, and they were completely freaked out.”

Because we are more sophisticated than our ape brethren, we are exquisitely tuned to subtle cues of difference. And those differences need not be physical, although when we band into groups, we often create physical differences by grooming ourselves in what amount to invented species markers, whether it’s the wide-brimmed hats and studded boots of swaggering Texans or the shaven heads and flowing orange robes of Hare Krishna followers. “We have words for things and can symbolize and abstract,” Goodenough says. “You can’t say, ‘The reason Germany is down and out is because of the Jews’ until you can abstract. That’s at the core of any fundamentalist group.”

The answer, Goodenough says, is to become familiar with what is different, like the multiracial kids at the Iowa day care center: “You can still label it as a difference, but without judgment. We all know some people are smarter than others, and some are nicer than others, some are musical, and some can’t carry a tune. The problem is we are each embedded in our hierarchies, but at the same time we say all men are created equal. It’s emblazoned on our constitution. It ain’t true, and we know it. The best we can offer is an equal chance.”

Brent Kennedy’s path to spirituality and the Pandora’s box of his own genome began when he almost died of a rare auto-immune disease called sarcoidosis, a condition more common in non-Caucasians than whites. “I was incapacitated,” he says. “I had searing fevers, lost my hair, had lung adhesions, and ended up in a wheelchair certain I was going to die.”

After six months of medicine and meditation, he went into remission. “Something just kind of happened two weeks into it, and I accepted it and decided to try and learn from it. I don’t even pretend to know the nature of God, all I know is that God is there and there’s a purpose to our lives. So I’d lie in bed and meditate on getting well, and think about my life and my family.” When he recovered, Brent quit work, took his life savings and began a quest to find out why he had sarcoidosis. He was certain the answer lay in his family’s lineage.

Brent’s family settled in the Appalachian mountains of southwestern Virginia and Eastern Tennessee in the early 1700s. He grew up being taught that he was of English and Scotch-Irish origin—like all his neighbors. At age nine, however, he began to question his roots.

“I went to the Coal Town Theater in nearby Norton and saw the movie Lawrence of Arabia. I sat there in that darkened theater and thought, ‘My family doesn’t look like the English. My family looks like the Arabs. My mother looks like she walked out of the Sahara desert.’ And a lot of people in the mountains of Appalachia look like this.” His family, however, had little to say when he questioned them. Later, on fishing trips to the mountain lakes, he sometimes encountered dark-complexioned people who belonged to an Appalachian group known as Melungeons. “They were a mystery people. I thought my mother looked like them. I asked my Dad and he just looked surprised and went about his work. So I decided my family was just a funny-looking group of English people.”

In 1988, after recovering from sarcoidosis, Brent began to interview all of his living relatives about their background. It took two years, and a few relatives were so angered they refuse to speak to Brent today. “I was asking about race, and that’s not something people want to talk about. What I discovered is that I had Melungeon ancestry through all four of my grandparents, and really heavily on my mother’s side. I had discovered a mystery heritage.” He also discovered that all his life he’d suffered from another rare ailment: Familial Mediterranean Fever (FMF). Once properly diagnosed, he was treated and his symptoms disappeared. Both FMF and sarcoidosis are common in Melungeons.

Who were the Melungeons? They’d preserved an oral history that was scoffed at by scholars. They claimed to have Turkish, Portuguese, and Mediterranean blood. Back in the sixteenth century, it is said, Sir Francis Drake dropped fifteen hundred Turkish and Mediterranean captives on Roanoke Island; not long after, Spanish and Portuguese soldiers were abandoned in the Carolinas and Tennessee. Brent became convinced that the Appalachian Mountains had become a kind of safe haven and melting pot for dark-skinned immigrants pushed out of colonial towns by Caucasians.

The genetics now back up the oral histories. Two years ago, University of Virginia botanist Kevin Jones began to analyze locks of hair from eighty Melungeon women and swabs of cheek cells from forty Melungeon men. Tested against the National Institutes of Health’s encyclopedia of genetic sequences from around the world, he has found exotic DNA from northern India and the Middle East. The study is still to be completed, but it’s intriguing that diseases to which Melungeons are susceptible—such as FMF—are also more commonly found in the Mediterranean. Brent knows thirteen other Melungeons with FMF. All are being successfully treated.

“One of the most amazing things to me,” Brent says, “is that the Melungeon people want the genetics. They’re not afraid. We want to prove that the old Melungeon ancestors were not lying; they were to the best of their ability trying to tell people who they really were. We’ve been taught the preferred history of the settlement of this country. We weren’t taught about Turks and Armenians and gypsies and Jews settling here in the 1600s. Yet I can take you to the most isolated family cemeteries here and show you tombstones with carved stars of David. I trust these people. These were my ancestors; they knew who they were even if American historians did not. You can change your name and your language, but your cultural artifacts and your genetics remain.”

Ultimately, Brent says, he hopes the genetic studies show something more profound about identity. “What is pure? What the heck is an Irishman anyway? A Viking, a Scot, a Celt? If you take the vast majority of Americans and run their DNA, they’ll be in for some surprises. The truth is, nobody is who they think they are.”

That’s the true challenge of our genetic map—to look without flinching at the ways we differ and the ways we are the same. To give the science its full measure, without corrupting it in service of myth and history. To understand that, in the end, identity is not fixed and impermeable with clear boundaries, but an ever-evolving creation. As it should be.