Napoleon Alphonseau Chagnon (August 27, 1938 – September 21, 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. 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. His work centered on the analysis of violence among tribal peoples, and, using socio-biological analyses, he advanced the argument that violence among the Yanomami is fueled by an evolutionary process in which successful warriors have more offspring. His 1967 ethnography Yanomamö: The Fierce People became a bestseller and is frequen