William Irons

Intergroup aggression in chimpanzees and humans.

The occurrence of fatal attacks during intergroup encounters among chimpanzees suggests that certain aspects of chimpanzee and human intergroup aggression may be explicable in similar ways. This paper addresses three questions: What conditions favor the evolution of lethal raiding in intergroup aggression? Why is intergroup aggression in these two species predominantly the domain of males? Under what circumstances do groups compete over access to females as opposed to material resources? Examination of comparative data on nonhuman primates and crosscultural study of foraging societies suggests that attacks are lethal because where there is sufficient imbalance of power their cost is trivial, that these attacks are a male and not a female activity because males are the philopatric sex, and that it is resources of reproductive interest to males that determine the causes of intergroup aggression.

Adaptation and human behavior : an anthropological perspective

This volume presents state-of-the-art empirical studies working in a paradigm that has become known as human behavioral ecology. The emergence of this approach in anthropology was marked by publication by Aldine in 1979 of an earlier collection of studies edited by Chagnon and Irons entitled Evolutionary Biology and Human Social Behavior: An Anthropological Perspective. During the two decades that have passed since then, this innovative approach has matured and expanded into new areas that are explored here. The book opens with an introductory chapter by Chagnon and Irons tracing the origins of human behavioral ecology and its subsequent development. Subsequent chapters, written by both younger scholars and established researchers, cover a wide range of societies and topics organ-ized into six sections. The first section includes two chapters that provide historical background on the development of human behavioral ecology and com-pare it to two complementary approaches in the study of evolution and human behavior, evolutionary psychology, and dual inheritance theory. The second section includes five studies of mating efforts in a variety of societies from South America and Africa. The third section covers parenting, with five studies on soci-eties from Africa, Asia, and North America. The fourth section breaks somewhat with the tradition in human behavioral ecology by focusing on one particularly problematic issue, the demographic transition, using data from Europe, North America, and Asia. The fifth section includes studies of cooperation and helping behaviors, using data from societies in Micronesia and South America. The sixth and final section consists of a single chapter that places the volume in a broader critical and comparative context. The contributions to this volume demonstrate, with a high degree of theoretical and methodological sophistication--the maturity and freshness of this new paradigm in the study of human behavior. The volume will be of interest to anthropologists and other professions working on the study of cross-cultural human behavior.

The Evolution of the Capacity for Culture: Sociobiology, Structuralism, and Cultural Selectionism [and Comments and Replies]

Cultural selectionism is a Darwinian approach to the understanding of human culture which, in constrast to sociobiology, holds that cultural evolution proceeds solely on the phenotypic level. Unlike structuralism, cultural selectionism predicts that the form taken by any culture will reflect historical processes rather than underlying, genetically induced biases of the human mind. Genetic selection, however, must be invoked to explain both the origin of the human capacity for culture and the maintenance of this genetic capacity in modern humans. Both the origin and the maintenance of the genetic capacity for culture in humans are most realistically modeled if we assume that culture is fundamentally an adaptation to the social, as opposed to the natural, environment.