For humans and many other animals, gender is a fact of life. Most individuals are born either male or female and their sex will have an enormous influence on their behaviour, physiology and life history. In this review, I consider the effect gender has on lifespan. In particular, I discuss the role played by behaviour, immunity and oxidative damage in determining sex‐dependent differences in longevity. I consider existing explanations for the effect of gender on lifespan and how these explanations fit (...) together. Finally, I expand on the recent suggestion of a key role for the insulin/IGF‐1 signalling pathway in regulating sex‐dependent differences in lifespan(1) and I highlight a number of areas for future investigation. BioEssays 29:795–802, 2007. © 2007 Wiley Periodicals, Inc. (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)

Misunderstandings often develop when scientists from different backgrounds use the same words (e.g., “selection”) when they mean different things by them. Theorists must therefore choose and define their terms carefully. In addition, proponents of “new” theories need to demonstrate empirically that theirs are more powerful than the existing theories they wish to supplant. Wilson & Sober have not yet done this.

Sex differences in mortality rates stem from genetic, physiological, behavioral, and social causes that are best understood when integrated in an evolutionary life history framework. This paper investigates the Male-to-Female Mortality Ratio (M:F MR) from external and internal causes and across contexts to illustrate how sex differences shaped by sexual selection interact with the environment to yield a pattern with some consistency, but also with expected variations due to socioeconomic and other factors.

The evolution of cooperative breeding is complex, and particularly so in humans because many other life history traits likely evolved at the same time. While cooperative childrearing is often presumed ancient, the transition from maternal self-reliance to dependence on allocare leaves no known empirical record. In this paper, an exploratory model is developed that incorporates probable evolutionary changes in birth intervals, juvenile dependence, and dispersal age to predict under what life history conditions mothers are unable to raise children without adult (...) cooperation. The model’s outcome variable (net balance) integrates dependent children’s production and consumption as a function of varying life history parameters to estimate the investment mothers or others have to spend subsidizing children. Results suggest that maternal-juvenile cooperation can support the early transition toward a reduction in birth intervals, a longer period of juvenile dependence, and having overlapping young. The need for adult cooperation is most evident when birth intervals are short and age at net production is late. Findings suggest that the needs of juveniles would not have been an early selective force for adult cooperation. Rather, an age-graded division of labor and the mutual benefits of maternal-juvenile cooperation could be an important, but overlooked step in the evolution of cooperative breeding. (shrink)

Geary's model is a worthy effort, but ambiguous on important issues. It ignores differential resource allocation, although this follows directly from sexual selection via differential parental investment. Dimorphism in primary traits is arbitrarily attributed to sexual selection via intramale competition, rather than direct evolutionary pressures. Dubious predictions are made about the consequences of raising mathematics achievement.

Among the extra-physical aspects of team sports, the ways in which players talk to each other are among the more colorful but understudied dimensions of competition. To contribute an empirical basis for examining the nature of “trash talk,” we present the results of a study of 291 varsity athletes who compete in the top division among US universities. Based on a preliminary review of trash-talk topics among student-athletes, we asked participants to indicate the frequency with which they have communicated or (...) heard others talk about opposing players’ athleticism, playing ability, physical appearance, boyfriends, girlfriends, sexual behavior, parents, and home institution during competitions. Our three main findings are: Trash-talking is most commonly about the proximately important topic of playing ability while ultimately relevant topics such as physical appearance also appear to be common; Men appear to trash-talk significantly more than women, and consistently across topics; and contact sports such as football, hockey, lacrosse, and wrestling are associated with trash talk significantly more than other sports. We also examined whether the anonymity provided by face-masked helmets in “combat sports” was associated with more trash talk than contact sports played without a helmet and found no consistent association with face masks. Our findings highlight the ways in which competitors in physical sporting contests attempt to use language—often in ways that focus on players’ kin or reproductive interests—in pursuit of victory while establishing a baseline for future research into trash-talking. (shrink)

Geary's emphasis on hunting ignores the possible importance of other human activities, such as scavenging and gathering, in the evolution of spatial abilities. In addition, there is little evidence that links spatial abilities and math skills. Furthermore, such links have little practical importance given the small size of most differences and girls' superior performance in mathematics classrooms.

The six commentaries raise five issues about multi-level selection theory that we attempt to address: (1) replicators without vehicles, (2) group selection and movement between groups, (3) absolute versus relative fitness, (4) group-level psychological adaptions, and (5) multi-level selection as a predictive theory.

Group selection may be defined either broadly or narrowly. Narrowly defined group selection may involve either selection for altruism or group selection between alternative evolutionarily stable states. The last variety of group selection is likely to have been particularly important in human evolution.

The theory of sexual selection suggests several possible explanations for the development of standards of physical attractiveness in humans. Asymmetry and departures from average proportions may be markers of the breakdown of developmental stability. Supernormal traits may present age- and sex-typical features in exaggerated form. Evidence from social psychology suggests that both average proportions and (in females) “neotenous” facial traits are indeed more attractive. Using facial photographs from three populations (United States, Brazil, Paraguayan Indians), rated by members of the same (...) three populations, plus Russians and Venezuelan Indians, we show that age, average features, and (in females) feminine/neotenous features all play a role in facial attractiveness. (shrink)

To the extent that Geary's theory concerning biologically primary and secondary behaviors depends on factor analytic methods and findings, it is woefully weak. Factors have been mistakenly called primary mental abilities, but the adjective “primary” represents reification of a mathematical dimension defined by correlations. Fleshing out a factor beyond its mathematical properties requires much additional quantitative experimental and correlational research that goes far beyond mere factoring.

The life of George Price (1922-1975), the eccentric polymath genius and father of the Price equation, is used as a prism and counterpoint through which to consider an age-old evolutionary conundrum: the origins of altruism. This biographical project, and biography and history more generally, are considered in terms of the possibility of using form to convey content in particular ways. Closer to an art form than a science, this approach to scholarship presents both a unique challenge and promise.

A number of philosophers and ‘evolutionary psychologists’ have argued that attacks on adaptationism in contemporary biology are misguided. These thinkers identify anti-adaptationism with advocacy of non-adaptive modes of explanation. They overlook the influence of anti-adaptationism in the development of more rigorous forms of adaptive explanation. Many biologists who reject adaptationism do not reject Darwinism. Instead, they have pioneered the contemporary historical turn in the study of adaptation. One real issue which remains unresolved amongst these methodological advances is the nature of (...) ‘phylogenetic inertia’. To what extent is an adaptive explanation needed for the persistence of a trait as well as its origin? (shrink)

This essay addresses recent claims about the compatibility of the sociobiological theory of reciprocal altruism with standard Western formulations of the Golden Rule. Derek Parfit claims that the theory of reciprocal altruism teaches us to be “reciprocal altruists,” who benefit only those people from whom we can reasonably expect benefits in the future. The Golden Rule, on the other hand, teaches us to benefit anyone regardless of their intention or ability to return the favor, or as Parfit puts it, the (...) Golden Rule teaches us to be “suckers.” I argue that this distinction is founded on a misconception of the nature of the theory of reciprocal altruism, which is sociobiological as opposed to moral, and that this distinction accordingly confuses is with ought. Sociobiological theories may explain underlying psychological motivations in individuals (and perhaps even in populations), but these theories do not prescribe any sort of moral behavior. Furthermore, the theory of reciprocal altruism does not imply mental states of which agents are aware. The unconscious motivations assumed by this theory are in fact compatible with certain formulations of the Golden Rule; I will accordingly argue for the view that certain words with moral content related to the Golden Rule—such as “altruism” and “selfishness”—exist only insofar as they are social tools, which can further the self-interests of an individual in any group. (shrink)

In Darwinian terminology, “sexual selection” refers to purely reproductive competition and is conceptually distinct from natural selection as it affects reproduction generally. As natural selection may favor the evolution of sexual dimorphism by virtue of the division of labor between males and females, this possibility needs to be taken very seriously.

Although classical evolutionary theory, i.e., population genetics and the Modern Synthesis, was already implicitly ‘gene-centred’, the organism was, in practice, still generally regarded as the individual unit of which a population is composed. The gene-centred approach to evolution only reached a logical conclusion with the advent of the gene-selectionist or gene’s eye view in the 1960s and 1970s. Whereas classical evolutionary theory can only work with fitness differences between individual organisms, gene-selectionism is capable of working with fitness differences among genes (...) within the same organism and genome. Here, we explore the explanatory potential of ‘intra-organismic’ and ‘intra-genomic’ gene-selectionism, i.e., of a behavioural-ecological ‘gene’s eye view’ on genetic, genomic and organismal evolution. First, we give a general outline of the framework and how it complements the—to some extent—still ‘organism-centred’ approach of classical evolutionary theory. Secondly, we give a more in-depth assessment of its explanatory potential for biological evolution, i.e., for Darwin’s ‘common descent with modification’ or, more specifically, for ‘historical continuity or homology with modular evolutionary change’ as it has been studied by evolutionary developmental biology during the last few decades. In contrast with classical evolutionary theory, evo-devo focuses on ‘within-organism’ developmental processes. Given the capacity of gene-selectionism to adopt an intra-organismal gene’s eye view, we outline the relevance of the latter model for evo-devo. Overall, we aim for the conceptual integration between the gene’s eye view on the one hand, and more organism-centred evolutionary models on the other. (shrink)

Although classical evolutionary theory, i.e., population genetics and the Modern Synthesis, was already implicitly ‘gene-centred’, the organism was, in practice, still generally regarded as the individual unit of which a population is composed. The gene-centred approach to evolution only reached a logical conclusion with the advent of the gene-selectionist or gene’s eye view in the 1960s and 1970s. Whereas classical evolutionary theory can only work with (genotypically represented) fitness differences between individual organisms, gene-selectionism is capable of working with fitness differences (...) among genes within the same organism and genome. Here, we explore the explanatory potential of ‘intra-organismic’ and ‘intra-genomic’ gene-selectionism, i.e., of a behavioural-ecological ‘gene’s eye view’ on genetic, genomic and organismal evolution. First, we give a general outline of the framework and how it complements the—to some extent—still ‘organism-centred’ approach of classical evolutionary theory. Secondly, we give a more in-depth assessment of its explanatory potential for biological evolution, i.e., for Darwin’s ‘common descent with modification’ or, more specifically, for ‘historical continuity or homology with modular evolutionary change’ as it has been studied by evolutionary developmental biology (evo-devo) during the last few decades. In contrast with classical evolutionary theory, evo-devo focuses on ‘within-organism’ developmental processes. Given the capacity of gene-selectionism to adopt an intra-organismal gene’s eye view, we outline the relevance of the latter model for evo-devo. Overall, we aim for the conceptual integration between the gene’s eye view on the one hand, and more organism-centred evolutionary models (both classical evolutionary theory and evo-devo) on the other. (shrink)

A recent dispute between Richard Dawkins and Edward O. Wilson concerning fundamental concepts in sociobiology is examined. It is argued that sociobiology has not fared well since the 1970s, and that its survival as a ‘scientific’ perspective has been increasingly tenuous. This is, at least in part, because it has failed to move forward in the ways its developers anticipated, but also because it has not seen the developments in natural history, genomics and social science it was relying upon. It (...) is argued that sociobiology has become a purely utilitarian perspective, a way of looking at things, reliant increasingly on studies of the behaviour of social insects for its scientific credentials. The dispute between Dawkins and Wilson is then reconsidered in this light, and it is argued that – regardless of which position prevails – sociobiology’s parlous state as a means of explaining action is now difficult to disguise. (shrink)

Geary suggests that implicit mathematical principles exist across human cultures and transcend sex differences. Is such knowledge present in animals as well, and is it sufficient to account for performance in all species, including our own? I attempt to trace the implications of Gearys target article for comparative psychology, questioning the exclusion of “subitizing” in describing human mathematical performance, and asking whether human researchers function as cultural agents with animals, elevating their implicit knowledge to secondary domains of numerical performance.

Geary is highly selective in his use of the literature on gender differences. His assumption of consistent female inferiority in mathematics is not necessarily supported by the facts.

In this commentary, we attempt to broaden thinking and dialogue about how our ancestral past might have affected attachment and reproductive strategies. We highlight the theoretical benefits of formulating specific predictions of how different sources of stress might impact attachment and reproductive strategies differently, and we integrate some of these ideas with another recent evolutionary model of human mating.

If selection at the group level is to be considered more than a mere possibility, it is important to find phenomena that are best explained at this level of selection. I argue that human religious phenomena provide evidence for the selection of a “pious gene” at the group level, which results in a human tendency to believe in a transcendental reality that encourages behavioral conformity to collective as opposed to individual interest.

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)

This article gives a short presentation of reflexive imperativism, the intentionalist theory of valence I developed with Max Khan Hayward. The theory says that mental states have valence in virtue of having reflexive imperative content. More precisely, mental states have positive valence (i.e., feel good) in virtue of issuing the command "More of me!", and they have negative valence (i.e., feel bad) in virtue of issuing the command "Less of me!" The article summarises the main arguments in favour of reflexive (...) imperativism and against other intentionalist treatments of valence. (shrink)