THERE'S NO SUCH THING AS SPECIES:

In late 2005, scientists reported the discovery of a gene mutation that had led to the first appearance of white skin in humans. Other than this minor mutation--just one letter of DNA code out of 3.1 billion letters in the human genome--most people are 99.9 percent identical genetically. And yet, what divisions have arisen as a result of such a seemingly inconsequential genetic anomaly. Moreover, this mutation had separated members of my family along tightly demarcated racial lines for three generations. As this discovery became known, I was invited to join a class on race relations at Pennsylvania State University in which all the students participated in DNA ancestry testing as a way of discussing contemporary attitudes about race and cultural identity.

Through the DNA tests, students came to realize that the racial or ethnic identities they grew up with were sometimes in conflict with their genetic material, belying the notion of racial purity. In class, I listened to students talk about racial labels and identities, and whether ancestry testing had changed their perceptions of themselves. Most embraced the newly found diversity that their DNA test revealed, and none felt that ancestry testing had changed their personal identities. Still, the discovery of mixed ancestry was a struggle for a few. One white student wondered whether her African heritage came from "a rape in my past," and another thought that her African DNA must have come from "promiscuous family members." These comments were indicative of the stigma that any hint of African ancestry carries for many white Americans. No one suggested that racial passing--which I'd immediately brought up in the discussion--might explain some of these traces of mixed heritage. Only one student even seemed to understand the idea of racial passing. He grew up in an interracial home, with a father of Jamaican descent and an Irish mother, and he was close to both sides of his family. Although issues of race were discussed openly at home, he told me, no one ever forced him to choose between being black and being white. And in spite of having fair skin, he did not claim to be white, choosing instead to forge his own identity as multiracial, thus embracing his phenotypic ambiguity.

When the instructor, sociologist Sam Richards, asked whether I would be interested in taking my own DNA ancestry test, as part of a larger DNA study being conducted by anthropologist Mark Shriver, I did not hesitate to say yes. Given that I already knew my mixed-race background, the results weren't shocking: 60 percent West African ancestry combined with 32 percent European, six percent East Asian, and two percent Native American. The East Asian ancestry was the only surprise, but Mark explained that Asians and Native Americans are closely related evolutionarily. (Several years later, I took a second and more sophisticated DNA test that revealed slightly different results: 50 percent African, 44 percent European, and six percent Asian. These two sets of results are within the margin of error.)

Outside Mark's office at Penn State, I studied a wall of photographs showing the faces of various people from his DNA study, from Penn State and around the world, each image accompanied by the ethnic designation that person identified with. Beside the photograph was a paper flap, which, when lifted, showed what a DNA sample revealed about that person's ethnic background. As I went through photograph after photograph, few of the personal ethnic identities matched the DNA profiles. Most people had some mixture of DNA from at least two groups; many, like me, had genetic ancestry from Europe, East Asia, West Africa, and Native American groups. Blond people had African and Asian ancestry, and several dark-skinned people had more than half of their DNA from Europe.

What we see when we look at a person may or may not correlate to his or her ancestral and ethnic background. DNA results confirmed for me that identity cannot be constructed based on a "percentage" of African ancestry, and that our society's generally accepted racial categories cannot begin to address the complexity and nuance of our heritage. I soon began to think about race only in terms of culture and biology together. And as race became an abstract rather than a concrete concept, the categorical ways in which I had thought about race in the past were quickly broken down. Once we see how small the differences are that bring about the characteristics we think of as racial--hair, skin color, eyes, facial features--in relation to the entire human genome, it's hard to make a fuss about them. Our differences are astonishingly slight.

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