To reliably identify the major sources of disease, one would need to collect demographic data in many villages and map it against the various forms of contact. As it happens, this is just what Chagnon did, and he gradually concluded that the Catholic missions were serious sources of disease, largely because of their regular roles as points of contact and entry. Yanomamö living at the missions benefited from the medical care, but those living close enough to catch their diseases yet too far to get the medical care suffered. When Chagnon saw the pattern, he blew the whistle. This did not endear him to the missionaries, who have ever since been the source of enough anti-Chagnon anecdotes to keep an enterprising journalist busy for years.
Similarly, Tierney says that competition over the pots and machetes and other steel tools that Chagnon gave the Yanomamö sometimes led to war. This too is logically possible. The Yanomamö certainly valued Chagnon's gifts, since cutting the jungle back for their crops was much easier with machetes. But Tierney fails to mention that Chagnon's contributions (made so that he would be allowed to collect data) were dwarfed by all the other sources of such items, such as the military, who hired Yanomamö laborers, and especially the vast mission system, which imports boatloads of machetes and other goods, and even has its own airline.
While Tierney considers Chagnon's distribution of steel tools an outrageous threat to peace, he amazingly gives a free pass to the introduction by others—including some missionaries—of hundreds of shotguns. These weapons are known to have been used by the Yanomamö in raiding from mission areas to the less well-armed villages where Chagnon worked. Chagnon blew the whistle on this, too.
In short, what Tierney leaves out of his story is that what his key sources have accused Chagnon of—causing disease and warfare—just happens to be what Chagnon had previously accused some of them of doing. Indeed, a prerequisite of Tierney's ability to do research in this restricted area was almost certainly his endorsement of one side in this feud. Tierney's translators, his guides, his selection of interviewees—all carry the strong implication that he received a guided tour drenched with these local politics. Throughout the book, Tierney goes to extraordinary lengths to explain away real causes of disease and violence that trace back to his patrons. (He has a whole appendix devoted to attacking evidence that the missionaries spread disease.) When this context is supplied, the unremitting denunciations of Chagnon start to sound different, and Tierney, The New Yorker's intrepid "Reporter At Large," appears in a less flattering light.
Chagnon has made enemies in academia as well as in the rain forest. Anthropology is full of people who still subscribe to Rousseau's "noble savage" view of human nature, and their battles with Chagnon have been intense. That is why Tierney could pepper his New Yorker article, and his book, with anthropologists who question Chagnon's Yanomamö data—a technique of great rhetorical power unless you know about all the anthropologists Tierney doesn't mention whose data support Chagnon. Chagnon's longtime critics include Turner and Sponsel, a fact that explains their uncritical and hyperbolic embrace of the Tierney book, and a fact that isn't mentioned in their incendiary letter to the American Anthropological Association.
With experts increasingly coming forward to debunk various aspects of the Tierney book, the accusations against Neel and Chagnon "are crumbling by the hour," as it was put by Lou Marano of UPI, one of the few reporters to deeply examine the credibility of Tierney's charges. But much damage has already been done—and not just to the reputations of Neel and Chagnon. Tierney's claim that an immunization program can start an epidemic has been carried around the world in media reports. This myth could compromise the ability of health workers to administer such programs, especially in poor countries, and people could die as a result. Moreover, indigenous cultures will not benefit from the public's impression that they are endangered only by the occasional anthropologist, when in fact they are victims of far more powerful forces, ranging from well-meaning missionaries to untrammeled modernization.
The slow-motion tragedy of the world's indigenous peoples continues, and Tierney's thoroughly dishonest book is just one more exploitation of them.