Chagnon also has many sympathizers in the major media, perhaps because of the growing popularity of the cultural views that his research supports. In short, Chagnon seems to have considerably more famous firepower on his side, and that adds up to a significant public relations advantage in the United States and Britain. I soon discovered, when I began asking questions, that many of Chagnon's friends are certain, even before they have read Tierney's book, that the charges against Chagnon, Neel and other anthropologists will prove to be merely "ugly politics." They confidently frame the conflict as Chagnon's manly "hard evidence" against his softheaded critics' "emotional assertions."

So, are Tierney's red-hot allegations about Neel and Chagnon legitimate?

Tierney's most shocking suggestion -- played for all it was worth by Turner and Sponsel -- is that in 1968, Atomic Energy Commission geneticist Neel, his protégé Chagnon and a respected Venezuelan physician named Marcel Roche deliberately inoculated a sample population of Yanomami Indians with Edmonston B, a dangerous and totally inappropriate live-virus measles vaccine. Coincidentally with the vaccinations, and following the researchers' path, a full-blown measles epidemic broke out among the Yanomami. Tierney quotes several people who hint darkly that an epidemic might have been exactly what Neel was seeking.

Neel, who died in February, considered himself, as he titled his 1994 autobiography, a "Physician to the Gene Pool." He thought that modern culture, with its supportive interventions on behalf of the weak, was "dysgenic." It had strayed too far from humankind's original "population structures": small, relatively isolated tribal groups where men competed with one another -- violently -- for access to women. In these societies, Neel assumed, the best fighters would have the most wives and children, and pass on more of their genetic "index of innate ability" to the next generation, leading to a continual upgrading of the quality of the gene pool. But among modern humans, Neel wrote, the "loss of headmanship as a feature of our culture, as well as the weakening of other vehicles of natural selection, is clearly a minus."

Tierney never establishes what definitive data he thinks Neel's tiny research team could have hoped to obtain in the midst of a widespread, out-of-control epidemic. But there were things Neel would have been anxious to discover about Yanomami resistance to disease. Historically, small and isolated populations tend to become more and more susceptible to "contact diseases" from outsiders, and all those generations of genetic improvement might go for naught if a village could be wiped out in a matter of days by an intruding microbe. On the other hand, if the "best" males of Neel's ideal tribal societies also had better resistance to disease, an epidemic would be likely to further concentrate their superior genes.

Susan Lindee, of the Department of the History and Sociology of Science at the University of Pennsylvania, reviewed Neel's 1968 field notes on the epidemic immediately after hearing about Turner and Sponsel's letter to the AAA. "Neel was a Cold Warrior deluxe, and an elitist," she wrote in an e-mail summarizing her findings. He was "confident about his hierarchical rankings of races, sexes, civilizations, fields of knowledge production, and forms of social organization." She suggested that his confidence may even have extended to seeing the Yanomami as "primitives" who could be legitimately used for research into the conditions of human evolution.

But her review of Neel's notes indicates that the outbreak of measles caught Neel and Chagnon very much by surprise. Tierney himself found audiotapes in the National Archives, recorded by filmmaker Timothy Asch during the first days of the epidemic, that show that Neel and Chagnon were increasingly distressed and puzzled at the astonishing coincidence of their vaccinations and a virulent outbreak of measles. Putting Neel's field notes and Tierney's narrative together, it seems highly unlikely that Neel and Chagnon actually intended to start an epidemic. But that doesn't mean they didn't start it unintentionally.

Maya Angelou reads from "The Heart of a Woman"