The fundamental postulate of sociobiology is that individuals exploit favorable environments to increase their genetic representation in the next generation. The data on fertility differentials among contemporary humans are not cotvietent with this postulate. Given the importance ofHomo sapiensas an animal species in the natural world today, these data constitute particularly challenging and interesting problem for both human sociobiology and sociobiology as a whole.The first part of this paper reviews the evidence showing an inverse relationship between reproductive fitness and “endowment” (...) in contemporary, urbanized societies. It is shown that a positive relationship is observed only for those cohorts who bore their children during a unique period of rising fertility, 1935–1960, and that these cohorts are most often cited by sociobiologists as supporting the central postulate of sociobiology. Cohorts preceding and following these show the characteristic inverse relationship between endowment and fertility. The second section reviews the existing so-ciobiological models of this inverse relationship, namely, those of Barkow, Burley, and Irons, as well as more informal responses among sociobiologists to the persistent violation of sociobiology's central postulate, such as those of Alexander and Dawkins. The third section asks whether the goals of sociobiology, given the violation of its fundamental postulate by contemporary human societies, might not be better thought of as applied rather than descriptive, with respect to these societies. A proper answer to this question begins with the measurement of the pace and direction of natural selection within modern human populations, as compared to other sources of change. The vast preponderance of the shifts in human trait distributions, including the IQ distribution, appears to be due to environmental rather than genetic change. However, there remains the question of just how elastic these distributions are in the absence of reinforcing genetic change. (shrink)

Anecdotal evidence from many hunter-gatherer societies suggests that successful hunters experience higher prestige and greater reproductive success. Detailed quantitative data on these patterns are now available for five widely dispersed cases (Ache, Hadza, !Kung, Lamalera, and Meriam) and indicate that better hunters exhibit higher age-corrected reproductive success than other men in their social group. Leading explanations to account for this pattern are: (1) direct provisioning of hunters’ wives and offspring, (2) dyadic reciprocity, (3) indirect reciprocity, (4) costly signaling, and (5) (...) phenotypic correlation. I examine the qualitative and quantitative evidence bearing on these explanations and conclude that although none can be definitively rejected, extensive and apparently unconditional sharing of large game somewhat weakens the first three explanations. The costly signaling explanation has support in some cases, although the exact nature of the benefits gained from mating or allying with or deferring to better hunters needs further study. (shrink)

In most social species, position in the male social hierarchy and reproductive success are positively correlated; in humans, however, this relationship is less clear, with studies of traditional societies yielding mixed results. In the most economically advanced human populations, the adaptiveness of status vanishes altogether; social status and fertility are uncorrelated. These findings have been interpreted to suggest that evolutionary principles may not be appropriate for the explanation of human behavior, especially in modern environments. The present study tests the adaptiveness (...) of social status with actual mating and reproductive data in a representative sample of males from an industrial society. Reproductive success, even when assessed by a more reliable measure ofactualmale fertility than the one commonly used, fails to correlate with social status. In striking contrast, however, status is found to be highly correlated withpotentialfertility, as estimated from copulation frequency. Status thus accounts for as much as 62% of the variance in thisproximatecomponent of fitness. This pattern is remarkably similar to what is found in many traditional societies and would result in a substantial positive relationship between cultural and reproductive success in industrial populations were it not for the novel conditions imposed by contraception and monogamy. Various underlying mechanisms are suggested for these findings, illustrating the value of current behavioral and reproductive data in the study of adaptation. It is concluded that evolutionary explanations of human behavior remain entirely relevant in modern societies. (shrink)

This paper presents and criticizes. Alexander's evolutionary theory of morality (1987). Earlier research, on which Alexander's theory is based, is also reviewed. The propensity to create moral systems evolved because it allowed ancestral humans to limit conflict within cooperating groups and thus form larger groups, which were advantageous because of intense between-group competition. Alexander sees moral codes as contractual, and the primary criticism of his theory is that moral codes are not completely contractual but also coercive. Ways of evaluating Alexander's (...) theory as well as modified versions of it are discussed. (shrink)