Final answer:
Napoleon Chagnon's research characterizes the Yanomamo society as hunter-gatherers and horticulturalists with a notable practice of warfare and a complex sociopolitical structure based on kinship and marriage alliances. They have an egalitarian social structure, along with gender-based division of labor and feasting practices for political negotiation.
Step-by-step explanation:
According to anthropologist Napoleon Chagnon, Yanomamo society is characterized by its social structures and cultural practices that reflect their subsistence as a hunter-gatherer and horticulturalist group. The Yanomamo, residing in the Amazon rainforest along the border between Venezuela and Brazil, are known for their warfare practices and aggressive stance which has historically been a dominant aspect of their culture. Chagnon's studies reveal a complex sociopolitical system with emphasis on kinship, alliance forming through marriage, and a notable feature of feasting called 'reahu' which is used as a political tool.
Their society practices a division of labor based on gender, with men generally handling hunting and inter-village affairs, while women are primarily involved in gardening and domestic tasks. The Yanomamo maintain strong egalitarian values but also have hierarchical elements in the form of village headmen, though these leaders do not wield absolute power. Chagnon's work has stirred controversy, emphasizing the Yanomamo's violent conflicts, which some critics argue, overstated the levels of violence and did not sufficiently account for the impact of outside influence on their society.