Napoleon Alphonseau Chagnon (27 August 1938 – 21 September 2019) was an American cultural anthropologist, professor of sociocultural anthropology at the University of Missouri in Columbia and member of the National Academy of Sciences.

[2] Chagnon was known for his long-term ethnographic field work among the Yanomamö, a society of indigenous tribal Amazonians, in which he used an evolutionary approach to understand social behavior in terms of genetic relatedness.

[15][16] In 2000, Patrick Tierney, in his book Darkness in El Dorado, accused Chagnon and his colleague James V. Neel of unethical behavior, such as, among other things, manipulating data, and exacerbating a measles epidemic among the Yanomamö people.

Their report, which was issued by the AAA in May 2002, held that Chagnon had both represented the Yanomamö in harmful ways and failed in some instances to obtain proper consent from both the government and the groups he studied.

[20] Alice Dreger, a historian of medicine and science, concluded after a year's research that Tierney's claims were false and the American Anthropological Association was complicit and irresponsible in helping spread these falsehoods and not protecting "scholars from baseless and sensationalistic charges".

[3] The anthropologist Brian Ferguson argued that Yanomamö culture is not particularly violent, and that the violence that does exist is largely a result of socio-political reconfigurations of their society under the influence of colonization.

[14][24] Sahlins claimed that Chagnon's trade of steel weaponry for blood samples and genealogical information amounted to "participant-instigation" which encouraged economic competition and violence.

[3] In his autobiography, Chagnon stated that most criticisms of his work were based on a postmodern and antiscientific ideology that arose within anthropology, in which careful study of isolated tribes was replaced in many cases by explicit political advocacy that denied less pleasant aspects of the Yanomamö culture, such as warfare, domestic violence, and infanticide.

Chagnon stated that much of his work has undermined the idea of the 'Noble savage' – a romanticized stereotype of indigenous people living in synchrony with nature and uncorrupted by modern civilization.

[35] Chagnon also stated that his beliefs about sociobiology and kin selection were misinterpreted and misunderstood, similarly because of a rejection of scientific and biological explanations for culture within anthropology.

[37][38] Chagnon worked with ethnographic filmmaker Tim Asch to produce at least forty films on Yanomamo culture,[39] including The Feast (1969), Magical Death (1973) and The Ax Fight (1975).