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Human Behavioral Ecology at Twenty-Five Evolutionary Anthropology 51 ARTICLES Analyzing Adaptive Strategies: Human Behavioral Ecology at Twenty-Five BRUCE WINTERHALDER AND ERIC ALDEN SMITH INTRODUCTION cesses of resource competition and tionally termed “behavioral ecology.” transfers, now supplement and enrich Behavioral analyses have been an in- Human behavioral ecology (HBE) those of resource production. Demo- tegral element of evolutionary ecology began in the mid-1970s with the ap- graphic and life history analyses have from the beginning, treating topics plication of optimal foraging models begun to show how ecological factors such as foraging strategies,27 mating to hunter-gatherer decisions concern- of production and distribution relate systems,30 and spatial organization ing resource selection and land use. In to those of mortality, fertility, and life and competition.32 The first textbooks the 25 years since, the field has devel- course. on behavioral ecology appeared in oped and successfully adapted evolu- Besides providing a comprehensive late 1970s33 and early 1980s.34 There tionary ecology theory and methods view of the field, we hope to demon- now is a voluminous literature, in- to a wide range of topics important to strate that HBE has established itself cluding monograph series, dedicated archaeology and to anthropology gen- as a progressive research tradition,1 a journals (e.g., Evolutionary Ecology, erally. In this review we examine the Behavioral Ecology and Sociobiol- basic theory and its extensions to chil- question we take up in our conclu- and dren’s foraging, conservation biology, sion. We note that this review supple- ogy), and a widely read, state-of-the- 35–38 demographic transitions, domestica- ments others. Two edited collections art series of volumes, each edition tion and agricultural origins, the evo- summarized the state of HBE in the with a new set of papers. 2 3 lution of menopause, field processing early 1980s and early 1990s; shorter Human behavioral ecology applies 4–6 and central place foraging, life his- reviews have appeared as well. A evolutionary ecology models and con- tory, male-female division of labor, pending collection carries us to the cepts to the study of human behav- 7 mating tactics and fertility decisions, late 1990s. Reviews of HBE general- ioral diversity. HBE began in the mid- 8,9 and resource intensification. Work on ly, as well as life history and demog- 1970s with a small set of interpretive 10–12 13 39–41 resource acquisition continues, but raphy, maturation, primate life papers and independent disserta- 14 has been extended from foragers to span and litter size, mating strate- tion projects. Initially centered on for- 15,16 17,18 pastoral and agricultural production gies, reproductive ecology, re- aging theory and hunter-gatherer systems. Studies of resource distribu- source transfers,19 resource conserva- studies, HBE has expanded over the tion, and especially intragroup pro- tion,20 and division of labor21 have last 25 years to encompass diverse appeared previously in this Journal. topics and subsistence systems (Fig. Evolutionary ecology studies “evo- 1). Although a second generation of lution and adaptive design in ecologi- HBE researchers is now in academic cal context.”22 As a distinct field, evo- positions, the field is young enough Bruce Winterhalder is Professor of Anthro- pology and Chair of the Curriculum in Ecol- lutionary ecology emerged in the that its initiators remain the majority ogy at University of North Carolina, Chapel 1960s with the work of Charnov and of those publishing in it. Hill. He currently is working on a book- 23 24,25 26 length analysis of the microecological Orians, Hutchinson, Lack, HBE’s early goals were to set the bases of the hunter-gatherer mode of pro- MacArthur and Pianka,27 MacArthur cultural ecology of Steward,42 partic- duction. E-mail: [email protected] and Levins,28 MacArthur,29 Ori- ularly as developed in his hunter-gath- Eric Alden Smith is Professor of Anthro- pology and Director of the Graduate Pro- ans,30,31 and others. Textbooks on evo- erer work43 and as represented in later gram in Environmental Anthropology at lutionary ecology appeared in the studies such as those by Lee,44 on a University of Washington, Seattle. He is currently engaged in studies of marine 1970s, covering topics from the struc- sounder theoretical footing by allying foraging, reproductive strategies, and so- tural and behavioral traits of organ- it to emerging, neo-Darwinian ap- cial status among Torres Strait Islanders isms to the organization of ecological proaches to behavior. From the start, in collaboration with Rebecca Bliege Bird and Douglas W. Bird. E-mail: communities. Evolutionary ecology the proposed alliance was a somewhat [email protected] shares fuzzy boundaries with evolu- wary and selective one. To varying de- tionary genetics, community ecology, grees, there were attempts to distance animal behavior, and decision theory. this anthropological effort (some- Key words: behavioral ecology; foraging strate- 2 gies; human adaptation; human evolution; hu- When applied to the analysis of behav- times termed “socioecology” ) from man life history; reproductive strategies ior, evolutionary ecology is conven- the sociobiology of Wilson,45 and 52 Evolutionary Anthropology ARTICLES particularist tradition of anthropolo- gy.70 HBE assumes that complex so- cioecological phenomenon are most fruitfully studied in a reductionist rather than holistic fashion. However, the methods of HBE and anthropology overlap in a common concern with ethnography: the ex- tended recording of behavioral obser- vations in their immediate socioenvi- ronmental context, often in small communities in remote and materi- ally impoverished conditions, supple- mented with data collected by survey, interview, or archival research. Here the uncluttered predictions of simple models meet the messy reality of field- work and participant observation. Al- HBE is an anomaly within sociocultural anthropology due to its hypothetico-deductive research strategy and its neo-Darwinian Figure 1. A tabulation of theoretical sources. HBE HBE publications, by topic and decade. The topical derives testable divisions correspond to sections of this article, with hypotheses from “Other” representing publi- mathematical or cations that cross these boundaries (e.g., review graphical models articles) or do not fit neatly in any of them. As indi- anchored in basic cated, the graph is divided principles of evolution into ethnographic, ar- chaeological, and com- by natural selection. bined tabulations. The count is based on a com- bination of the authors’ personal bibliographic da- tabases, plus a survey of though HBE is more committed to selected journals and re- cent review articles (we quantitative methods that reliably thank Geoff Kushnick for document observable behavior than is bibliographic assistance). sociocultural anthropology generally, it is rare that key variables can be controlled, samples randomized, or more recently from the approach sources. HBE derives testable hypoth- replication achieved. HBE research- known as evolutionary psychology eses from mathematical or graphical ers share field methods with their so- (see Box 1). models anchored in basic principles ciocultural colleagues, but within a of evolution by natural selection. Em- theoretical and epistemological phasizing generality, most HBE mod- framework that is alien to that field. THEORY AND METHOD IN HBE els strive to be as simple as possible. A complete HBE explanation com- HBE is an anomaly within sociocul- They seek to capture the essential fea- bines models of circumstance and tural anthropology due to its hypo- tures of an adaptive problem, and ne- models of mechanism.71 Models of cir- thetico-deductive research strategy glect to some degree the myriad ancil- cumstance ask, “How do socioenvi- and its neo-Darwinian theoretical lary variables of concern in the more ronmental factors shape the costs and ARTICLES Evolutionary Anthropology 53 Box 1. HBE Compared to Some Closely Related Fieldsa Behavioral ecology Evolutionary psychology Dual inheritance theory Explanatory focus Behavioral strategies Psychological mechanisms Cultural evolution Key constraints Ecological, material Cognitive, genetic Structural, information Temporal scale of Short-term Long-term (genetic) Medium-term (cultural) adaptive change (phenotypic) Expected current Highest Lowest Intermediate adaptiveness Hypothesis generation Optimality and ESS Informal inference Population-level models models Primary hypothesis-testing Quantitative Survey, laboratory Mathematical modeling methods ethnographic experiment and simulation observation Favored topics Subsistence, Mate choice, sex differences Cooperation, reproductive maladaptation strategies a Modified from Smith.46 HBE is only one of several distinct approaches to evolutionary analysis of human behavior that have developed in recent years; other prominent ones include evolutionary psychology and dual inheritance theory. Here we offer a brief comparison with these two fields.46–49 Evolutionary psychology (EP) aims to uncover the evolved “psychological mechanisms that underpin human...be- havior,” and “the selective forces that shaped those mechanisms”50 (see reviews51–54). EP posits that human behavior is guided by specialized cognitive modules rather than “general purpose” mechanisms that work across multiple behavioral domains. It argues that these modules evolved in the EEA (environment of evolutionary adaptedness), and are designed to
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