Much clinical and ethnographic evidence suggests that humans, like many other organisms, are selected to avoid close inbreeding because of the fitness costs of inbreeding depression. The proximate mechanism of human inbreeding avoidance seems to be precultural, and to involve the interaction of genetic predispositions and environmental conditions. As first suggested by E. Westermarck, and supported by evidence from Israeli kibbutzim, Chinese sim-pua marriage, and much convergent ethnographic and clinical evidence, humans negatively imprint on intimate associates during a critical period (...) of early childhood.There is also much evidence that, like other social animals, humans do not seek to maximize outbreeding, but rather to maintain an optimal balance between outbreeding and inbreeding.Closeinbreeding reduces fitness through inbreeding depression, butsomeinbreeding brings the benefits of nepotism. For simple, stateless, horticultural societies, the optimal balance seems to be achieved by a combination of precultural inbreeding avoidance of relatives with anr≤·25 and cultural rules of preferential marriage with kin withr≥·25. Adjustment of the coefficient of inbreeding to other ecological settings seems to be largely cultural. An interactive model of “culture in nature” is presented, in which culture is seen as coevolving with genes to produce the maxiniization of individual inclusive fitness. (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)

Recent studies of the evolution of religion have revealed the cognitive underpinnings of belief in supernatural agents, the role of ritual in promoting cooperation, and the contribution of morally punishing high gods to the growth and stabilization of human society. The universality of religion across human society points to a deep evolutionary past. However, specific traits of nascent religiosity, and the sequence in which they emerged, have remained unknown. Here we reconstruct the evolution of religious beliefs and behaviors in early (...) modern humans using a global sample of hunter-gatherers and seven traits describing hunter-gatherer religiosity: animism, belief in an afterlife, shamanism, ancestor worship, high gods, and worship of ancestors or high gods who are active in human affairs. We reconstruct ancestral character states using a time-calibrated supertree based on published phylogenetic trees and linguistic classification and then test for correlated evolution between the characters and for the direction of cultural change. Results indicate that the oldest trait of religion, present in the most recent common ancestor of present-day hunter-gatherers, was animism, in agreement with long-standing beliefs about the fundamental role of this trait. Belief in an afterlife emerged, followed by shamanism and ancestor worship. Ancestor spirits or high gods who are active in human affairs were absent in early humans, suggesting a deep history for the egalitarian nature of hunter-gatherer societies. There is a significant positive relationship between most characters investigated, but the trait “high gods” stands apart, suggesting that belief in a single creator deity can emerge in a society regardless of other aspects of its religion. (shrink)

Despite its importance, the linkage between genetic and cultural evolution has until now been little explored. An understanding of this linkage is needed to extend evolutionary theory so that it can deal for the first time with the phenomena of mind and human social history. We characterize the process of gene-culture coevolution, in which culture is shaped by biological imperatives while biological traits are simultaneously altered by genetic evolution in response to cultural history. A case is made from both theory (...) and evidence that genetic and cultural evolution are inseverable, and that the human mind has tended to evolve so as to bias individuals toward certain patterns of cognition and choice rather than others. With the aid of mathematical models we trace the coevolutionary circuit: The genes prescribe structure in developmental pathways that lay down endocrine and neural systems, imposing regularities in the development of cognition and behavior; these regularities translate upward into holistic patterns of culture, which can be predicted in the form of probability density distributions ; natural selection acts within human history to favor certain epigenetic rules over others; and the selection alters the frequencies of the underlying genes. The effects of genetic and cultural changes reverberate throughout the circuit and are consequently tested with the passage of each life cycle. In addition to modeling gene-culture coevolution, we apply methods from island biogeography and information theory to examine the cultural capacity of the genes, the factors determining the magnitude of cultural diversity, and the possible reasons for the uniqueness of the human achievement. (shrink)

Cooperation towards public goods relies on credible threats of punishment to deter cheats. However, punishing is costly, so it remains unclear who incurred the costs of enforcement in our evolutionary past. Theoretical work suggests that human cooperation may be promoted if people believe in supernatural punishment for moral transgressions. This theory is supported by new work in cognitive psychology and by anecdotal ethnographic evidence, but formal quantitative tests remain to be done. Using data from 186 societies around the globe, I (...) test whether the likelihood of supernatural punishment—indexed by the importance of moralizing “high gods”—is associated with cooperation. (shrink)

This article argues that feminist analyses of patriarchy should be expanded to address the evolutionary basis of male motivation to control female sexuality. Evidence from other primates of male sexual coercion and female resistance to it indicates that the sexual conflicts of interest that underlie patriarchy predate the emergence of the human species. Humans, however, exhibit more extensive male dominance and male control of female sexuality than is shown by most other primates. Six hypotheses are proposed to explain how, over (...) the course of human evolution, this unusual degree of gender inequality came about. This approach emphasizes behavioral flexibility, cross-cultural variability in the degree of partriarchy, and possibilities for future change. (shrink)

Teaching is hypothesized to be a species-typical behavior in humans that contributed to the emergence of cumulative culture. Several within-culture studies indicate that foragers depend heavily on social learning to acquire practical skills and knowledge, but it is unknown whether teaching is universal across forager populations. Teaching can be defined ethologically as the modification of behavior by an expert in the presence of a novice, such that the expert incurs a cost and the novice acquires skills/knowledge more efficiently or that (...) it would not acquire otherwise. One behavioral modification hypothesized to be an adaptation for teaching is ostensive communication—exaggerations of prosody and gesture that signal intent to transmit generalizable knowledge and indicate the intended receiver. On this view, the use of ostensive communication in conjunction with the transmission of generalizable knowledge constitutes evidence of teaching. Oral storytelling appears to meet these criteria: Indigenous peoples regard their traditions as important sources of ecological and social knowledge, and oral storytelling is widely reported to employ paralinguistic communication. To test this hypothesis, descriptions of performed narrative in forager societies were coded for the use of 14 ostensive-communicative behaviors and the presence of generalizable knowledge. Although biased toward North America, the study sample comprised 53 forager cultures spanning five continents, 34 language families, and diverse biomes. All cultures evinced the predicted behaviors. Results suggest that foragers use storytelling as a mode of instruction, thus providing cross-cultural evidence of teaching in forager populations. (shrink)

Moral behaviour, based on social norms, is commonly regarded as a hallmark of humans. Hitherto, humans are perceived to be the only species possessing social norms and to engage in moral behaviour. There is anecdotal evidence suggesting their presence in chimpanzees, but systematic studies are lacking. Here, we examine the evolution of human social norms and their underlying psychological mechanisms. For this, we distinguish between conventions, cultural social norms and universal social norms. We aim at exploring whether chimpanzees possess evolutionary (...) precursors of universal social norms seen in humans. Chimpanzees exhibit important preconditions for their presence and enforcement: tolerant societies, well-developed social-cognitive skills and empathetic competence. Here, we develop a theoretical framework for recognizing different functional levels of social norms and distinguish them from mere statistical behavioural regularities. Quasi social norms are found where animals behave functionally moral without having moral emotions. In proto social norms, moral emotions might be present but cannot be collectivized due to the absence of a uniquely human psychological trait, i.e. shared intentionality. Human social norms, whether they are universal or cultural, involve moral emotions and are collectivized. We will discuss behaviours in chimpanzees that represent potential evolutionary precursors of human universal social norms, with special focus on social interactions involving infants. We argue that chimpanzee infants occupy a special status within their communities and propose that tolerance towards them might represent a proto social norm. Finally, we discuss possible ways to test this theoretical framework. (shrink)

Emotions can be the subject of moral judgments; they can also constitute the basis for moral judgments. The apparent circularity which arises if we accept both of these claims is the central topic of this paper: how can emotions be both judge and party in the moral court? The answer I offer regards all emotions as potentially relevant to ethics, rather than singling out a privileged set of moral emotions. It relies on taking a moderate position both on the question (...) of the naturalness of emotions and on that of their objectivity as revealers of value: emotions are neither simply natural nor socially constructed, and they apprehend objective values, but those values are multidimensional and relative to human realities. The axiological position I defend jettisons the usual foundations for ethical judgments, and grounds these judgments instead on a rationally informed reflective equilibrium of comprehensive emotional attitudes, tempered with a dose of irony. (shrink)

Work was conducted among traditional, subsistence whale hunters in Lamalera, Indonesia, in order to test if strict biological kinship or lineage membership is more important for explaining the organization of cooperative hunting parties ranging in size from 8 to 14 men. Crew identifications were collected for all 853 hunts that occurred between May 3 and August 5, 1999. Lineage identity and genetic relatedness were determined for a sample of 189 hunters. Results of matrix regression show that genetic kinship explains little (...) of the hunters’ affiliations independent of lineage identity. Crew members are much more closely related to each other than expected by chance, but this is due to the correlation between lineage membership and genetic kinship. Lineage members are much more likely to affiliate in crews, but kin with r<0.5 are just as likely not to affiliate. The results are discussed vis-à-vis the evolution of cooperation and group identity. (shrink)

I argue that the magnitude and nature of sex differences in aggression, their development, causation, and variability, can be better explained by sexual selection than by the alternative biosocial version of social role theory. Thus, sex differences in physical aggression increase with the degree of risk, occur early in life, peak in young adulthood, and are likely to be mediated by greater male impulsiveness, and greater female fear of physical danger. Male variability in physical aggression is consistent with an alternative (...) life history perspective, and context-dependent variability with responses to reproductive competition, although some variability follows the internal and external influences of social roles. Other sex differences, in variance in reproductive output, threat displays, size and strength, maturation rates, and mortality and conception rates, all indicate that male aggression is part of a sexually selected adaptive complex. Physical aggression between partners can be explained using different evolutionary principles, arising from the conflicts of interest between males and females entering a reproductive alliance, combined with variability following differences in societal gender roles. In this case, social roles are particularly important since they enable both the relatively equality in physical aggression between partners from Western nations, and the considerable cross-national variability, to be explained. (shrink)

Many evolutionary models assume that behaviors are caused directly by genes. An implication is that behavioral uniformity should be found only in groups that are genetically uniform. Yet, the members of human social groups often behave in a uniform fashion, despite the fact that they are genetically diverse. Behavioral uniformity can occur through a variety of psychological mechanisms and social processes, such as imitation, consensus decision making, or the imposition of social norms. We present a series of models in which (...) genes code for social transmission rules, which in turn govern the behaviors that are adopted. Transmission rules can evolve in randomly formed groups that concentrate phenotypic variation at the between-group level, favoring the evolution of altruistic behaviors and other group-advantageous traits. In addition, a direct bias toward adopting altruistic behaviors can evolve. Our models begin to show how group selection can be a strong force in human evolution, despite the absence of extreme genetic variation among groups. (shrink)

We present a cross-cultural analysis showing that the presence of an active or moral High God in societies varies generally along a continuum from lesser to greater technological complexity and subsistence productivity. Foragers are least likely to have High Gods. Horticulturalists and agriculturalists are more likely. Pastoralists are most likely, though they are less easily positioned along the productivity continuum. We suggest that belief in moral High Gods was fostered by emerging leaders in societies dependent on resources that were difficult (...) to manage and defend without group cooperation. These leaders used the concept of a supernatural moral enforcer to manipulate others into cooperating, which resulted in greater productivity. Reproductive success would accrue most to such leaders, but the average reproductive success of all individuals in the society would also increase with greater productivity. Supernatural enforcement of moral codes maintained social cohesion and allowed for further population growth, giving one society an advantage in competition with others. (shrink)

This paper investigates the impact of kin on child survival in a matrilineal society in Malawi. Women usually live in close proximity to their matrilineal kin in this agricultural community, allowing opportunities for helping behavior between matrilineal relatives. However, there is little evidence that matrilineal kin are beneficial to children. On the contrary, child mortality rates appear to be higher in the presence of maternal grandmothers and maternal aunts. These effects are modified by the sex of child and resource ownership: (...) female children and children in households where women, rather than men, own land suffer higher mortality rates in the presence of maternal kin. These modifiers suggest the detrimental effects of matrilineal kin may result from competition between such kin for resources. There are some positive effects of kin on child survival: the presence of elder siblings of both sexes is correlated with higher survival rates, and there is some weak evidence that paternal grandmothers may be beneficial to a child’s survival chances. There is little evidence that any male kin, whether matrilineal or patrilineal, and including fathers, affect child mortality rates. This study highlights the importance of taking social and ecological context into account when investigating relationships between kin. (shrink)

Current debates about “Darwinizing culture” have typically focused on the validity of memetics. In this article we argue that meme-like inheritance is not a necessary requirement for descent with modification. We suggest that an alternative and more productive way of Darwinizing culture can be found in the application of phylogenetic methods. We review recent work on cultural phylogenetics and outline six fundamental questions that can be answered using the power and precision of quantitative phylogenetic methods. However, cultural evolution, like biological (...) evolution, is often far from treelike. We discuss the problems reticulate evolution can cause for phylogenetic analyses and suggest ways in which these problems can be overcome. Our solutions involve a combination of new methods for the study of cultural evolution , and the triangulation of different lines of historical evidence. Throughout we emphasize that most debates about cultural phylogenies can only be settled by empirical research rather than armchair speculation. (shrink)

Across the world people in different societies structure their family relationships in many different ways. These relationships become encoded in their languages as kinship terminology, a word set that maps variably onto a vast genealogical grid of kinship categories, each of which could in principle vary independently. But the observed diversity of kinship terminology is considerably smaller than the enormous theoretical design space. For the past century anthropologists have captured this variation in typological schemes with only a small number of (...) model system types. Whether those types exhibit the internal co-selection of parts implicit in their use is an outstanding question, as is the sufficiency of typologies in capturing variation as a whole. We interrogate the coherence of classic kinship typologies using modern statistical approaches and systematic data from a new database, Kinbank. We first survey the canonical types and their assumed patterns of internal and external co-selection, then present two data-driven approaches to assess internal coherence. Our first analysis reveals that across parents’ and ego’s generation, typology has limited predictive value: knowing the system in one generation does not reliably predict the other. Though we detect limited co-selection between generations, “disharmonic” systems are equally common. Second, we represent structural diversity with a novel multidimensional approach we term kinship space. This approach reveals, for ego’s generation, some broad patterning consistent with the canonical typology, but diversity is considerably higher than classical typologies suggest. Our results strongly challenge the descriptive adequacy of the set of canonical kinship types. (shrink)

A historical survey of the inheritance practices of farming families in North America and elsewhere indicates that resource allocations among children differed through time and space with regard to sex bias and equality. Tensions between provisioning all children and maintaining a productive economic entity (the farm) were resolved in various ways, depending on population pressures, the family’s relative resource level, and the number and sex of children.Against a backdrop of generalized son preference, parents responded to ecological circumstances by investing in (...) offspring differentially within and between the sexes. Vesting the preponderance of family resources in one heir increased the likelihood of at least one line surviving across several generations, whereas varying degrees of parental investment in emigrating sons or out-marrying daughters might yield boom or bust harvests of grandchildren according to circumstances in more remote locales. Primogeniture (eldest son as primary heir) allowed early identification of heirs and appropriate socialization, as well as more time for parents to contribute to the heir’s reproductive success. Son bias and unigeniture decreased as numbers of children per family declined, as land became less critical to economic success, and as legal changes improved the resource-holding potential of females. We suggest that changing ecological conditions affected parental decisions regarding resource allocation among children at least as much as did changing ideologies of parent-child relations. (shrink)

MOST MODERN PEOPLE think it is obvious why people become modern. For them, a more interesting and important puzzle is why some people fail to embrace modern ideas. Why do people in traditional societies often seem unable or unwilling to aspire to a better life for themselves and their children? Why do they fail to see the benefi ts of education, equal rights, democracy, and a rational approach to decisionmaking? What is the glue that makes them adhere to superstition, religion, (...) and obligations to family and tribe even if it means accepting a life of insecurity and poverty? The “kin infl uence hypothesis” (Newson et al. 2005) suggests an explanation both for why people become modern and for why modern ideas are often slow to be accepted by a population. The hypothesis is based on the understanding gained by social-psychological research of how cultural norms change. It takes a Darwinian approach to explaining human behavior and recognizes that much of the cultural change associated with modernization is a progressive abandonment of values and norms that encourage people to pursue what evolutionary theorists refer to as “reproductive success.”1 The kin infl uence hypothesis proposes that the cascade of cultural changes associated with modernization is the result of the momentous change in the human social environment that occurs early in economic development. For most of human evolutionary history, the norms of all cultures must have prescribed behavior that, on balance, enhanced the genetic fi tness of their members. If this were not the case, then, as Lumsden and Wilson (1981) and Alexander (1979) rightly pointed out, evolutionary biologists would be unable to explain how humans evolved the uniquely human capacity for learning and imitation that makes culture possible. Nor could we explain how an African ape came to be the world’s dominant organism. With economic development, however, people begin to abandon the beliefs and values that encourage fi tness-enhancing behavior.. (shrink)

Dyadic play fighting occurs in many species, but only humans are known to engage in coalitional play fighting. Dyadic play fighting is hypothesized to build motor skills involved in actual dyadic fighting; thus, coalitional play fighting may build skills involved in actual coalitional fighting, operationalized as forager lethal raiding. If human psychology includes a motivational component that encourages engagement in this type of play, evidence of this play in forager societies is necessary to determine that it is not an artifact (...) of agricultural or industrial conditions. We examine whether coalitional play fighting appears in the hunter-gatherer record and includes motor skills used in lethal raiding. Using the ethnographic record, we generated a list of motor patterns regularly used in forager warfare. Then, using Murdock’s Ethnographic Atlas, we identified 100 culture clusters containing forager societies and searched the ethnographic records of these societies for descriptions of coalitional play fighting, operationalized as contact games played in teams. Resulting games were coded for the presence of eight motor patterns regularly used in forager lethal raiding. Although play does not tend to be systematically documented in the hunter-gatherer literature, sufficiently detailed descriptions of coalitional play were found for 46 of the 100 culture clusters: all 46 exhibited coalitional play using at least one of the predicted motor patterns; 39 exhibited coalitional play using four or more of the eight predicted motor patterns. These results provide evidence that coalitional play fighting occurs across a diverse range of hunter-gatherer cultures and habitats, regularly recruits motor patterns used in lethal raiding, and is not an artifact of agricultural or industrial life. This is a first step in a new line of research on whether human male psychology includes motivations to engage in play that develops the deployment of coordinated coalitional action involving key motor patterns used in lethal raiding. (shrink)

Children may be viewed as public goods whereby both parents receive equal genetic benefits yet one parent often invests more heavily than the other. We introduce a microeconomic framework for understanding household investment decisions to address questions concerning conflicts of interest over types and amount of work effort among married men and women. Although gains and costs of marriage may not be spread equally among marriage partners, marriage is still a favorable, efficient outcome under a wide range of conditions. This (...) bioeconomic framework subsumes both cooperative and conflictive views on the sexual division of labor. We test hypotheses concerning marriage markets, assortative mating, and men’s labor motivations among Tsimane forager-horticulturalists of Bolivia and find that: (1) men and women both value work effort in marital partners, (2) marital labor contributions are complementary, (3) work effort is correlated between spouses, (4) total production is correlated with total reproduction, and (5) better hunters have higher fitness gains within marital unions. (shrink)

Cooperation for the public good is vulnerable to exploitation by free-riders because it always pays individuals to exploit the social contract for their own benefit. This problem can be resolved if free-riders are punished, but punishment is itself a public good subject to free-riding. The fear of supernatural punishment hypothesis (FSPH) proposes that belief in supernatural punishment might offer a solution to this problem by deflecting the cost of punishment onto supernatural forces and thereby incentivizing cooperation. FSPH is supported empirically (...) by ethnographic data, but this work has so far focused on (1) institutional cooperative traits which may not reflect individual choices on how to behave in everyday social interactions and (2) threat of punishment from all-powerful moralizing high gods rather than other agents capable of supernatural punishment. Here, we consider the FSPH using variables which are linked to individual interaction and expand the number of variables measuring belief in different forms of supernatural punishment. Our findings do not fit these more general FSPH predictions. We suggest there may be something special about the link between moralizing high gods and institutional enforcement of cooperation that is not captured by these other variables. (shrink)

Most research on mate choice in modern societies is based on data that may or may not reflect actual mating behavior (e.g., stated preferences, personal advertisements). In the present study, real-life matings were reported by a large representative sample of men and women (N = 1,133). These data were used to test an evolutionary model in which mate choice is hypothesized to depend on resources potentially contributed to reproduction by each sex. Consistent with the model, it was found that (a) (...) men (but not women) of higher social status acquire more mating partners, suggesting that male status is an important criterion in female choice; (b) women’s (but not men’s) number of partners decreases linearly with age, suggesting that female reproductive potential is an important criterion in male choice; and (c) women (but not men) display a significant relationship between marital dissolution and promiscuity, suggesting that female sexual exclusivity is an important criterion in male choice. These results are discussed in relation to understanding mate choice mechanisms from behavioral data. (shrink)

Significant amounts of wealth have been exchanged as part of marriage settlements throughout history. Although various models have been proposed for interpreting these practices, their development over time has not been investigated systematically. In this paper we use a Bayesian MCMC phylogenetic comparative approach to reconstruct the evolution of two forms of wealth transfers at marriage, dowry and bridewealth, for 51 Indo-European cultural groups. Results indicate that dowry is more likely to have been the ancestral practice, and that a minimum (...) of four changes to bridewealth is necessary to explain the observed distribution of the two states across the cultural groups. (shrink)

Contemporary mate preferences can provide important clues to human reproductive history. Little is known about which characteristics people value in potential mates. Five predictions were made about sex differences in human mate preferences based on evolutionary conceptions of parental investment, sexual selection, human reproductive capacity, and sexual asymmetries regarding certainty of paternity versus maternity. The predictions centered on how each sex valued earning capacity, ambition— industriousness, youth, physical attractiveness, and chastity. Predictions were tested in data from 37 samples drawn from (...) 33 countries located on six continents and five islands. For 27 countries, demographic data on actual age at marriage provided a validity check on questionnaire data. Females were found to value cues toresource acquisitionin potential mates more highly than males. Characteristics signalingreproductive capacitywere valued more by males than by females. These sex differences may reflect different evolutionary selection pressures on human males and females; they provide powerful cross-cultural evidence of current sex differences in reproductive strategies. Discussion focuses on proximate mechanisms underlying mate preferences, consequences for human intrasexual competition, and the limitations of this study. (shrink)

Despite its importance, the linkage between genetic and cultural evolution has until now been little explored. An understanding of this linkage is needed to extend evolutionary theory so that it can deal for the first time with the phenomena of mind and human social history. We characterize the process of gene-culture coevolution, in which culture is shaped by biological imperatives while biological traits are simultaneously altered by genetic evolution in response to cultural history. A case is made from both theory (...) and evidence that genetic and cultural evolution are inseverable, and that the human mind has tended to evolve so as to bias individuals toward certain patterns of cognition and choice rather than others. With the aid of mathematical models we trace the coevolutionary circuit: The genes prescribe structure in developmental pathways that lay down endocrine and neural systems, imposing regularities in the development of cognition and behavior; these regularities translate upward into holistic patterns of culture, which can be predicted in the form of probability density distributions ; natural selection acts within human history to favor certain epigenetic rules over others; and the selection alters the frequencies of the underlying genes. The effects of genetic and cultural changes reverberate throughout the circuit and are consequently tested with the passage of each life cycle. In addition to modeling gene-culture coevolution, we apply methods from island biogeography and information theory to examine the cultural capacity of the genes, the factors determining the magnitude of cultural diversity, and the possible reasons for the uniqueness of the human achievement. (shrink)

Cross-cultural studies have revealed broad quantitative associations between subsistence practice and demographic parameters for preindustrial populations. One explanation is that variationin the availability of suitable weaning foods influenced the frequency and duration of breastfeeding and thus the length of interbirth intervals and the probability of child survival (the “weaning food availability” hypothesis). We examine the available data on weaning age variation in preindustrial populations and report results of a cross-cultural test of the predictions that weaning occurred earlier in agricultural and (...) pastoral populations because dairy and cereal production increased the availability of easily digestible, nutrientrich foods appropriate for weaning. We found that, contrary to predictions, supplementation with liquid foods other than breast milk was delayed in agricultural populations relative to less agriculturally dependent ones and complementary feeding with solid foods was delayed in pastoral populations relative to those less dependent on herding. Although the duration of breastfeeding was longer in populations dependent on hunting, there was no qualitative evidence that such populations lacked foods appropriate for weaning. The patterns observed suggest that the relationships between demography and subsistence observed among preindustrial societies cannot be explained by the “weaning food availability” hypothesis. We discuss the implications for understanding the mechanisms underlying prehistoric human demography, subsistence shifts, allocation to parenting and mating effort, and the evolutionary implications of tradeoffs between diet and disease. (shrink)

Dispersal of individuals from their natal communities at sexual maturity is an important determinant of kin association. In this paper we compare postmarital residence patterns among Pumé foragers of Venezuela to investigate the prevalence of sex-biased vs. bilateral residence. This study complements cross-cultural overviews by examining postmarital kin association in relation to individual, longitudinal data on residence within a forager society. Based on cultural norms, the Pumé have been characterized as matrilocal. Analysis of Pumé marriages over a 25-year period finds (...) a predominant pattern of natalocal residence. We emphasize that natalocality, bilocality, and multilocality accomplish similar ends in maximizing bilateral kin affiliations in contrast to sex-biased residential patterns. Bilateral kin association may be especially important in foraging economies where subsistence activities change throughout the year and large kin networks permit greater potential flexibility in residential mobility. (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)

Stories in which a hero defeats a semi-human ogre occur much more frequently in unrelated cultures than chance alone can account for. This claim is supported by a discussion of folk-tales from 20 cultures and an examination of the folk-tales from a random sample of 44 cultures. The tendency to tell these stories must, therefore, have its source in the innate human nature discussed by evolutionary psychologists. This essay argues that these stories reinforce innate positive biases in the perception of (...) self and ingroup and negative biases in the perception of outgroups. (shrink)

Previous research on warfare in a worldwide sample of societies by Ember and Ember (Journal of Conflict Resolution, 36, 242–262, 1992a) found a strong relationship between resource unpredictability (particularly food scarcity caused by natural disasters) in nonstate, nonpacified societies and overall warfare frequency. Focusing on eastern Africa, a region frequently plagued with subsistence uncertainty as well as violence, this paper explores the relationships between resource problems, including resource unpredictability, chronic scarcity, and warfare frequencies. It also examines whether resource scarcity predicts (...) more resource-taking in land, movable property, and people, as well as the commission of atrocities. Results support previous worldwide results regarding the relationship between resource unpredictability and warfare frequency. Results regarding resource-taking and atrocities are more nuanced and complex. In almost all findings, relationships are generally in opposite directions in nonstate and state societies. In post-hoc analyses, atrocities are significantly more likely to be committed in states than in nonstates. (shrink)

This chapter focuses on the way that cultures change and how cultural diversity is created, maintained and lost. Human culture is the inevitable result of the way our species acquires its behavior. We are extremely social animals and an overwhelming proportion of our behavior is socially learned. The behavior of other animals is largely a product of innate evolved determinants of behavior combined with individual learning. They make quite modest use of social learning while we acquire a massive cultural repertoire (...) from the people we associate with (Richerson & Boyd, 2005: Chapter 2). Expertise in exploiting our environment, values about what matters in life and even feelings about whom to trust and whom to hate are mostly “absorbed” from those around us. (shrink)

The kin selection hypothesis posits that male androphilia (male sexual attraction to adult males) evolved because androphilic males invest more in kin, thereby enhancing inclusive fitness. Increased kin-directed altruism has been repeatedly documented among a population of transgendered androphilic males, but never among androphilic males in other cultures who adopt gender identities as men. Thus, the kin selection hypothesis may be viable if male androphilia was expressed in the transgendered form in the ancestral past. Using the Standard Cross-Cultural Sample (SCCS), (...) we examined 46 societies in which male androphilia was expressed in the transgendered form (transgendered societies) and 146 comparison societies (non-transgendered societies). We analyzed SCCS variables pertaining to ancestral sociocultural conditions, access to kin, and societal reactions to homosexuality. Our results show that ancestral sociocultural conditions and bilateral and double descent systems were more common in transgendered than in non-transgendered societies. Across the entire sample, descent systems and residence patterns that would presumably facilitate increased access to kin were associated with the presence of ancestral sociocultural conditions. Among transgendered societies, negative societal attitudes toward homosexuality were unlikely. We conclude that the ancestral human sociocultural environment was likely conducive to the expression of the transgendered form of male androphilia. Descent systems, residence patterns, and societal reactions to homosexuality likely facilitated investments in kin by transgendered males. Given that contemporary transgendered male androphiles appear to exhibit elevated kin-directed altruism, these findings further indicate the viability of the kin selection hypothesis. (shrink)