In both biology and the human sciences, social groups are sometimes treated as adaptive units whose organization cannot be reduced to individual interactions. This group-level view is opposed by a more individualistic one that treats social organization as a byproduct of self-interest. According to biologists, group-level adaptations can evolve only by a process of natural selection at the group level. Most biologists rejected group selection as an important evolutionary force during the 1960s and 1970s but a positive literature began to (...) grow during the 1970s and is rapidly expanding today. We review this recent literature and its implications for human evolutionary biology. We show that the rejection of group selection was based on a misplaced emphasis on genes as "replicators" which is in fact irrelevant to the question of whether groups can be like individuals in their functional organization. The fundamental question is whether social groups and other higher-level entities can be "vehicles" of selection. When this elementary fact is recognized, group selection emerges as an important force in nature and what seem to be competing theories, such as kin selection and reciprocity, reappear as special cases of group selection. The result is a unified theory of natural selection that operates on a nested hierarchy of units. The vehicle-based theory makes it clear that group selection is an important force to consider in human evolution. Humans can facultatively span the full range from self-interested individuals to "organs" of group-level "organisms." Human behavior not only reflects the balance between levels of selection but it can also alter the balance through the construction of social structures that have the effect of reducing fitness differences within groups, concentrating natural selection (and functional organization) at the group level. These social structures and the cognitive abilities that produce them allow group selection to be important even among large groups of unrelated individuals. (shrink)

In both biology and the human sciences, social groups are sometimes treated as adaptive units whose organization cannot be reduced to individual interactions. This group-level view is opposed by a more individualistic one that treats social organization as a byproduct of self-interest. According to biologists, group-level adaptations can evolve only by a process of natural selection at the group level. Most biologists rejected group selection as an important evolutionary force during the 1960s and 1970s but a positive literature began to (...) grow during the 1970s and is rapidly expanding today. We review this recent literature and its implications for human evolutionary biology. We show that the rejection of group selection was based on a misplaced emphasis on genes as “replicators” which is in fact irrelevant to the question of whether groups can be like individuals in their functional organization. The fundamental question is whether social groups and other higher-level entities can be “vehicles” of selection. When this elementary fact is recognized, group selection emerges as an important force in nature and what seem to be competing theories, such as kin selection and reciprocity, reappear as special cases of group selection. The result is a unified theory of natural selection that operates on a nested hierarchy of units.The vehicle-based theory makes it clear that group selection is an important force to consider in human evolution. Humans can facultatively span the full range from self-interested individuals to “organs” of group-level “organisms.” Human behavior not only reflects the balance between levels of selection but it can also alter the balance through the construction of social structures that have the effect of reducing fitness differences within groups, concentrating natural selection (and functional organization) at the group level. These social structures and the cognitive abilities that produce them allow group selection to be important even among large groups of unrelated individuals. (shrink)

An evolutionary theory of socialization suggests that children from father-absent families will mature earlier, and form less-stable pair bonds, compared with those from father-present families. Using a sample of about 1,000 persons the recent study focuses on elements of father-absent children’s behavior that could be better explained by a Darwinian approach than by rival social science theories. As a result of their enhanced interest in male competition, father-absent boys were found to engage in rule-breaking behavior more intensively than father-present boys. (...) Compared with father-present children, adolescents from widowed households (both boys and girls) showed a higher intensity of various kinds of noncompliant behavior, which can be linked to their earlier maturation. School attendance, age at marriage, and marital success proved to be influenced by the children’s early family experiences, governed by adapted evolutionary strategies. Father-absent daughters conceived more children than those whose fathers were present during their childhood. As evolutionary theory predicts, reproductive behavior of individuals from divorced households differed from that of individuals who grew up in widowed households. Finally, the strong correlation found between spontaneous abortion/stillbirths and family arrangement indicates that father absence has certain direct impacts on the neurohormonal processes of child development. (shrink)

Conspicuous consumption associated with status reinforcement behavior can be explained in terms of costly signaling, or strategic handicap theory, first articulated by Zahavi and later formalized by Grafen. A theory is introduced which suggests that the evolutionary raison d’être of status reinforcement behavior lies not only in its effects on lifetime reproductive success, but in its positive effects on the probability of survival through infrequent, unpredictable demographic bottlenecks. Under some circumstances, such “wasteful” displays may take the form of displays of (...) altruistic behavior and generosity on the part of high status individuals, in that is signals the ability to bear the short-term costs of being generous or “cooperative,” while at the same time reinforcing the long-term benefits of higher status. (shrink)

This paper investigates hypotheses drawn from two sources: (1) Belsky, Steinberg, and Draper’s (1991) attachment theory model of the development of reproductive strategies, and (2) recent life history models and comparative data suggesting that environmental risk and uncertainty may be potent determinants of the optimal tradeoff between current and future reproduction. A retrospective, self-report study of 136 American university women aged 19–25 showed that current recollections of early stress (environmental risk and uncertainty) were related to individual differences in adult time (...) preference and adult sexual behavior, and that individual differences in time preference were related to adult attachment organization and sexual behavior. These results are consistent with the hypothesis that perceptions of early stress index environmental risk and uncertainty and mediate the attachment process and the development of reproductive strategies. On this view individual differences in time preference are considered to be part of the attachment theoretical construct of an internal working model, which itself is conceived as an evolved algorithm for the contingent development of alternative reproductive strategies. (shrink)

The dissertation criticizes two analogical applications of Darwinism to the spheres of mind and culture: the Darwinian approach to creativity and memetics. These theories rely on three basic analogies: the ontological analogy states that the basic ontological units of culture are so-called memes, which are replicators like genes; the origination analogy states that novelty in human creativity emerges in a "blind" Darwinian manner; and the explanatory units of selection analogy states that memes are "egoistic" and that they can spread independently (...) of our mind. The detailed philosophical analysis offered in the dissertation shows that these three analogies rely on either wrong or trivial statements: they provide either wrong or no new descriptions or explanations of the phenomena at hand. In Chapter One, I introduce the diverse ways, in which contemporary Darwinism is used today outside of evolutionary biology. Chapter Two explains what it means to claim that something evolves in a Darwinian manner. Chapter Three to Five address each of the three analogies separately. Darwinism applied to culture and mind, at least in the way discussed in this study, is not a dangerous idea. It leads either to wrong claims or to a re-telling in Darwinian terms of what we have already known. (shrink)

We suggest that human culture exhibits key Darwinian evolutionary properties, and argue that the structure of a science of cultural evolution should share fundamental features with the structure of the science of biological evolution. This latter claim is tested by outlining the methods and approaches employed by the principal subdisciplines of evolutionary biology and assessing whether there is an existing or potential corresponding approach to the study of cultural evolution. Existing approaches within anthropology and archaeology demonstrate a good match with (...) the macroevolutionary methods of systematics, paleobiology, and biogeography, whereas mathematical models derived from population genetics have been successfully developed to study cultural microevolution. Much potential exists for experimental simulations and field studies of cultural microevolution, where there are opportunities to borrow further methods and hypotheses from biology. Potential also exists for the cultural equivalent of molecular genetics in “social cognitive neuroscience,” although many fundamental issues have yet to be resolved. It is argued that studying culture within a unifying evolutionary framework has the potential to integrate a number of separate disciplines within the social sciences. (shrink)

The various behavioral disciplines model human behavior in distinct and incompatible ways. Yet, recent theoretical and empirical developments have created the conditions for rendering coherent the areas of overlap of the various behavioral disciplines. The analytical tools deployed in this task incorporate core principles from several behavioral disciplines. The proposed framework recognizes evolutionary theory, covering both genetic and cultural evolution, as the integrating principle of behavioral science. Moreover, if decision theory and game theory are broadened to encompass other-regarding preferences, they (...) become capable of modeling all aspects of decision making, including those normally considered “psychological,” “sociological,” or “anthropological.” The mind as a decision-making organ then becomes the organizing principle of psychology. (Published Online April 27 2007) Key Words: behavioral game theory; behavioral science; evolutionary theory; experimental psychology; gene-culture coevolution; rational actor model; socialization. (shrink)

De modo semelhante aos rompantes etnocêntricos de uma cultura humana frente a outras, as relações entre humanos e primatas não humanos incluem um estranhamento pontuado por atração e repulsa, identificação e diferença. Ciência, arte e mitologia são a expressão viva e atualizada disso. Desde 1960, a primatologia destaca-se nesse cenário por contribuir significativamente na revisão das definições sobre o comportamento dos primatas e, consequentemente, na redefinição do humano ao apresentar a polêmica proposição de existência de "culturas" entre animais não humanos. (...) Assim, a aproximação entre humanos e primatas não humanos parece inexorável e irreversível. Isso implica, por exemplo, em cogitar se esse processo engendra, ou não, a constituição de novas alteridades a partir de um novo outro (não humano), carregado de significados. Isso incluiria, por exemplo, a reformulação de representações e de categorias de classificação, bem como o aprofundamento do debate sobre os direitos dos animais não humanos. Ao dirigir tal tipo de desafio a situações de pesquisa antropológica deve-se ter aguda consciência de que o registro etnográfico das relações entre humanos e os outros primatas será uma construção empírica, perceptual e teórica. Dado o tipo particular de relação estabelecida entre humanos e outros primatas, pautada em um universo fronteiriço de incômodas semelhanças e diferenças, constituem-se aí coletivos híbridos em que o alcance e a profundidade das interações possíveis ainda são desconhecidos. The relations between humans and non-human primates resemble the ethnocentric reaction of one human culture in relation to others, and include an estrangement marked by attraction and rejection, identification and differentiation. Art, science and myths are the vivid and updated expression of these phenomena. Since the 1960's primatology stands out in that scenario for contributing significantly to the revision of the definitions about the behavior of primates and, consequently, for the redefinition of human beings, and for making the controversial proposal of the existence of non-human animal "cultures". Then, the close connection between humans and non-human primates seems relentless and irreversible - and raises the question on whether or not these processes engender a new kind of otherness deriving from a non-human other that is full of meaning. This would include, for example, the reformulation of the representations and categories of classification, as well as deepening the debate about the rights of non-human animals. When the challenge is taken up in situations of anthropological research that address the relationships between human beings and the other primates, the ethnographic register that describes the relations between human beings and other primates will be an equally sharp empirical, perceptual and theoretical construction. Given the peculiar type of relationship established between human beings and other primates, implemented in a frontier universe of uncomfortable similarities and differences, they constituted a hybrid collective where interactions are possible but we do not know exactly how complex or how depth they are. (shrink)

I admire Wilson & Sober's (W & S's) aim, to alert social scientists that group selection has risen from the ashqs, and to explicate its relevance to the behavioral sciences. Group selection has beenwidely misunderstood; furthermore, both authors have been instrumental in illuminating conceptual problems surrounding higher-level selection. Still, I find that this target article muddies the waters, primarily through its shifting and confused definition of a "vehicle" of selection. The fundamental problem is an ambiguity in the definition of "adaptation." (...) On the one hand, any evolutionary change that results from a selection process could be called an adaptation, by definition; I call this the "weak" view of adaptation. A "strong" view of adaptation, on the other hand, includes some notion of design - the evolution of a specific complex trait understood, in an engineering sense, to provide a mechanism favoring its owner's success in contributing to the evolutionary lineage. (shrink)

Kinship was one of the key areas of research interest among anthropologists in the nineteenth century, one of the most hotly debated areas of theory in the early and mid-twentieth century, and yet an area of waning interest by the end of the twentieth century. Since then, the study of kinship has experienced a revitalization, with concomitant disputes over how best to proceed. This special issue brings together recent studies of kinship by scientific anthropologists employing evolutionary theory and quantitative methods. (...) We argue that the melding of the evolutionary theoretical perspective with quantitative and ethnographic methodologies has strengthened and reinvigorated the study of kinship by synthesizing and extending existing research via rigorous analyses of evidence. (shrink)

Prior to European influence, predation by Native Americans was the major factor limiting the numbers and distribution of ungulates in the Intermountain West. This hypothesis is based on analyses of (1) the efficiency of Native American predation, including cooperative hunting, use of dogs, food storage, use of nonungulate foods, and hunting methods; (2) optimal-foraging studies; (3) tribal territory boundary zones as prey reservoirs; (4) species ratios, and sex and age of aboriginal ungulate kills; (5) impact of European diseases on aboriginal (...) populations; and (6) synergism between aboriginal and carnivore predation. Native Americans had no effective conservation practices, and the manner in which they harvested ungulates was the exact opposite of any predicted conservation strategy. Native Americans acted in ways that maximized their individual fitness regardless of the impact on the environment. For humans, conservation is seldom an evolutionarily stable strategy. By limiting ungulate numbers and purposefully modifying the vegetation with fire, Native Americans structured entire plant and animal communities. Because ecosystems with native peoples are entirely different than those lacking aboriginal populations, a “hands-off” or “natural regulation” approach by today’s land managers will not duplicate the ecological conditions under which those ecosystems developed. The modern concept of wilderness as areas without human influence is a myth. North America was not a “wilderness” waiting to be discovered, instead it was home to tens of millions of aboriginal peoples before European-introduced diseases decimated their numbers. (shrink)

When wealth is heritable, parents may manipulate family size to optimize the trade-off between more relatively poor offspring and fewer relatively rich ones, and channel less care into offspring that compete with siblings. These hypotheses were tested with quantitative ethnographic data collected among the Karo Batak—patrilineal agriculturalists from North Sumatra, Indonesia, among whom land is bequeathed equally to sons. It was predicted that landholding would moderate the relationship between reproductive rate and parental investment on one hand, and the number of (...) same-sex siblings on the other, among boys but not girls. The predicted interaction effect was observed in interbirth intervals and immunizations, but only a trace of the effect was detected in age-five mortality. The study raises questions about the coevolution of human behavior and social structure. (shrink)

Health research has shown that overweight and obesity in children and adults are becoming significant public health problems in the developing world. Evidence suggests that this phenomenon is more marked in urban than rural areas and may be associated with modernization. However, the underlying reasons for this nutrition transition remain unclear. Dietary shifts, often in conjunction with income and time constraints in urban environments, may entail a greater reliance on more convenient sugar and fat-dense food. Also, the necessity of labor-intensive (...) agricultural work to meet rural subsistence needs is supplanted in urban environments by sedentary work. This paper extends the application of human behavioral ecology theory into the realm of international development and policy by applying Kaplan’s embodied capital theory to explore differences in food habits and nutritional status of Indo-Fijian children within the context of urbanization. Urban high-embodied-capital women demonstrate higher rates of wage-earning employment than urban low-embodied-capital or rural women. Findings indicate that urban high-embodied-capital households spend significantly more on food purchases, purchase a greater proportion of processed foods, and have children with higher body mass indexes (BMI) than do urban low-embodied-capital or rural households. This suggests that urban high-embodied-capital mothers, who tend to be employed, may be making trade-offs between income and food choices. (shrink)

Governments and non-govermental organizations (NGOs) that plan projects to conserve the environment and alleviate poverty often attempt to modify rural livelihoods by halting activities they judge to be destructive or inefficient and encouraging alternatives. Project planners typically do so without understanding how rural people themselves judge the value of their activities. When the alternatives planners recommend do not replace the value of banned activities, alternatives are unlikely to be adopted, and local people will refuse to participate. Human behavioral ecology and (...) behavioral economics may provide useful tools for generating and evaluating hypotheses for how people value economic activities in their portfolios and potential alternatives. This is demonstrated with a case example from southwestern Madagascar, where plans to create a Mikea Forest National Park began with the elimination of slash-and-burn maize agriculture and the encouragement to plant labor-intensive manioc instead. Future park plans could restrict access to wild tuber patches, hunting small game, and fishing. The value of these activities is considered using observational data informed by optimal foraging theory, and experimental data describing people’s time preference and covariation perception. Analyses suggest that manioc is not a suitable replacement for maize for many Mikea because the two crops differ in terms of labor requirements, delay-to-reward, and covariation with rainfall. Park planners should promote wild tuber foraging and stewardship of tuber patches and the anthropogenic landscapes in which they are found. To conserve small game, planners must provide alternative sources of protein and cash. Little effort should be spent protecting lemurs, as they are rarely eaten and never sold. (shrink)

This paper begins with the hypothesis that Mikea, participants in a mixed foraging–fishing–farming–herding economy of southwestern Madagascar, may attempt to reduce interannual variance in food supply caused by unpredictable rainfall by following a simple rule-of-thumb: Practice an even mix of activities that covary positively with rainfall and activities that covary negatively with rainfall. Results from a historical matrix participatory exercise confirm that Mikea perceive that foraging and farming outcomes covary positively or negatively with rainfall. This paper further considers whether Mikea (...) learn about covariation through personal observation and memory recall (individual learning) or through socially transmitted ethnotheory (social learning). Dual inheritance theory models by Boyd and Richerson (1988) predict that individual learning is more effective in spatially and temporally variable environments such as the Mikea Forest. In contrast, the psychological literature suggests that individuals judge covariation poorly when memory of past events is required, unless they share a socially learned theory that a covariation should exist (Nisbett and Ross 1980). Results suggest that Mikea rely heavily on shared ethnotheory when judging covariation, but individuals continually strive to improve their judgment through individual observation. (shrink)

Human behavioral ecology (HBE) began as an attempt to explain human economic, reproductive, and social behavior using neodarwinian theory in concert with theory from ecology and economics, and ethnographic methods. HBE has addressed subsistence decision-making, cooperation, life history trade-offs, parental investment, mate choice, and marriage strategies among hunter-gatherers, herders, peasants, and wage earners in rural and urban settings throughout the world. Despite our rich insights into human behavior, HBE has very rarely been used as a tool to help the people (...) with whom we work. This article introduces a special issue of Human Nature which explores the application of HBE to significant world issues through the design and critique of public policy and international development projects. The articles by Tucker, Shenk, Leonetti et al., and Neil were presented at the 104th annual meeting of the American Anthropological Association (AAA) in Washington, D.C., in December 2005, in the first organized session of the nascent Evolutionary Anthropology Section (EAS). We conclude this introduction by summarizing some theoretical challenges to applying HBE, and ways in which evolutionary anthropologists can contribute to solving tough world issues. (shrink)

Competition for resources is one of the main evolutionary explanations for dispersal from the natal area. For humans this explanation has received little attention, despite the key role dispersal is thought to play in shaping social systems. I examine the link between dispersal and resources using historical data on people from the small farming town of Oakham, Massachusetts (1750–1850). I reconstruct individual life histories through a variety of records, identifying dispersers, their age at dispersal, and their destinations. I find that (...) sex, father’s wealth and social status, and age at father’s death were all significantly associated with one or more dispersal variables. Birth order and number of siblings were not significantly associated with any of the dispersal variables. I also use wills and deeds to study transfers of land from fathers to sons. More stayers than dispersers acquired Oakham land from their fathers, but some sons who acquired Oakham land later dispersed. I discuss the causality underlying the relationship between dispersal and resource acquisition, as well as implications for a general understanding of human dispersal. (shrink)

Over the past two decades, archaeologists and physical anthropologists investigating the prehistoric Anasazi culture have identified numerous cases of suspected cannibalism. Many scholars have suggested that starvation caused by environmental degradation induced people to eat one another, but the growing number of cases as well as their temporal and spatial distribution challenge this conclusion. At the same time, some scholars have questioned the validity of the osteoarchaeological indicators that are used to identify cannibalism in collections of mutilated human remains. To (...) address these concerns, this study attempts to reconstruct the behaviors that produced the Anasazi skeletal trauma by first examining ethnographic, ethnohistoric, and archaeological material for analogues useful for interpreting mutilated human remains and then correlating these analogues with the evidence from the Southwest. The patterns suggest that different behaviors are responsible for the Anasazi skeletal mutilation seen in different time periods. To explain these differences, the study employs game theoretical models that examine how changing social and physical contexts altered the sociopolitical strategies that Anasazi groups would likely have employed. The results suggest that violent mutilation and perhaps cannibalism was an intentional sociopolitical strategy of intimidation used during Pueblo II (A.D. 900–1100), while environmental changes after this period promoted resource-based warfare and the incidental skeletal trauma associated with this behavior. (shrink)