Since Darwin proposed that human musicality evolved through sexual selection, empirical evidence has supported intersexual selection as one of the adaptive functions of artistic propensities. However, intrasexual competition has been overlooked. We tested their relative importance by investigating the relationship between the self-perceived talent/expertise in 16 artistic and 2 sports modalities and proxies of intersexual selection and intrasexual competition in heterosexuals. Participants were 82 Brazilian men, 166 Brazilian women, 146 Czech men, and 458 Czech women. (...) Factor analysis revealed five factors: Literary-arts, Visual-arts, Musical-arts, Circus-arts, and Sports. Multivariate General Linear Model showed more associations of the arts to intersexual selection in women and to intrasexual selection in men, and overall more relationships in women than in men. In women, literary and musical-arts were related to elevated inter- and intrasexual selections proxies, visual and circus-arts were related to elevated intersexual selection proxies, and sports were related to intrasexual selection proxies. In men, literary-arts and sports were related to elevated inter- and intrasexual selection proxies, musical-arts were related to intrasexual proxies, and circus-arts were related to intersexual proxies; visual-arts did not have predictors. Although present in both sexes, each sexual selection component has different relative importance in each sex. Artisticality functions to attract and maintain long/short-term partners, and to compete with mating rivals. (shrink)

Although "intrasexual selection" has been accepted as the mechanism by which males evolve elaborate secondary sexual traits which are used in aggressive contests, the importance of "intersexual selection" as a mechanism by which males have acquired exaggerated traits to display to females during courtship was less readily accepted. In spite of this scepticism, several genetic models have supported the latter idea, and many empirical studies showed that females were generally more discriminating in mate choice than males, because (...) of differences in relative investment between sexes. Nowadays, this idea is reinforced by various concepts (parental investment, potential reproductive rate, environmental potential for polygamy...) which stress that the strength of sexual selection is related to many interdependent factors, such as mating systems, resource distribution (food, habitat, mate), life history and other ecological characteristics. The case of Salmonids is presented here to show how novel information on sexual selection has contributed to the understanding of the plasticity of breeding patterns in the context of evolutionary biology. (shrink)

This article utilizes three premises. There are commonly ecologically oriented, naturally selected specialized differences in frequency and/or quality as well as sexually selected differences between the sexes. Sex in the sense of coming together and going apart or going apart and coming together is trade in these naturally selected differences, i.e., there is a mating market in sexual species. While such trade is beneficial to the population as a whole, sexual competition and selection is conflict over the profits of (...) that trade and can be detrimental to the population as a whole. These premises yield a naturally selected sex allocation theory of the possible directions and forms of sexual selection, i.e., one that includes costs as well as frequencies. This can explain conventional sex roles, the sex-role reversed, inter- as well as intrasexual selection, and passive as well as active choice. Any of these alternatives may be over mates, over gametes, or both. A hypothetical example based on density dependence relative to resources is provided, one that suggests that centrioles may be a cytoplasmic resource in males in multicellular animals, and which are the target of active choice and the mechanism of manipulation in passive female choice. As a whole, the approach yields a truly general theory of sexual selection, provides an alternative to the mechanism for Fisher’s principle, and gives a theoretical explanation for Mayr’s biological species definition. (shrink)

Vigil summarizes sex-related differences in emotivity, and presents a psychological model based on the restrictive assumption that responses to stimuli are dichotomous. The model uses for support the concept of intrasexual selection, but ignores intersexual selection. An alternative hypothesis might be that emotivity signals age: maturity in men and youth in women. Integration requires considering all evolutionary biology, not just agreeable concepts.

Del Giudice's model of sex-specific attachment patterns demonstrates the usefulness of infusing life history theory with principles of sexual selection. We believe a full synthesis between the two theories provides a foundation for a comprehensive model of alternative reproductive strategies. We extend Del Giudice's ideas based on our own program of research, focusing specifically on the importance of intrasexual competition and the individual phenotype during development.

Across taxa, strength and size are elementary determinants of relative fighting capacity; in species with complex behavioral repertoires, numerous additional factors also contribute. When many factors must be considered simultaneously, decision-making in agonistic contexts can be facilitated through the use of a summary representation. Size and strength may constitute the dimensions used to form such a representation, such that tactical advantages or liabilities influence the conceptualized size and muscularity of an antagonist. If so, and given the continued importance of physical (...) strength in human male-male conflicts, a man’s own strength will influence his conceptualization of the absolute size and strength of an opponent. In the research reported here, male participants’ chest compression strength was compared with their estimates of the size and muscularity of an unfamiliar potential antagonist, presented either as a supporter of a rival sports team (Study 1, conducted in urban California, and Study 2, conducted in rural Fiji) or as a man armed with a handgun (Study 3, conducted in rural Fiji). Consistent with predictions, composite measures of male participants’ estimates of the size/strength of a potential antagonist were inversely correlated with the participant’s own strength. Therefore, consonant with a history wherein violent intrasexual selection has acted on human males, a man’s own physical strength influences his representations of potential antagonists. (shrink)

Male-male competition is involved in inter- and intrasexual selection, with both endocrine and psychological factors presumably contributing to reproductive success in human males. We examined relationships among men’s naturally occurring testosterone, their self-perceived mate value, self-esteem, sociosexuality, and expected likelihood of approaching attractive women versus situations leading to child involvement. We then monitored changes in these measures in male rowers from Cambridge, UK, following a manipulated “win” or “loss” as a result of an indoor rowing contest. Baseline results (...) revealed that men with heightened testosterone and SPMV values typically had greater inclinations toward engaging in casual sexual relationships and a higher likelihood of approaching attractive women in a hypothetical social situation. As anticipated, both testosterone and SPMV increased following a manipulated “victory” and were associated with heightened sociosexuality, and increased expectations toward approaching attractive women versus individuals who would involve them in interacting with children after the race. SPMV and self-esteem appeared to mediate some of the effects of testosterone on post-race values. These findings are considered in the broader context of individual trade-offs between mating and parental effort and a model of the concurrent and dynamic androgenic and psychological influences contributing to male reproductive effort and success. (shrink)

Several theorists have tried to model anorexia on Wasser and Barash’s (1983) “reproductive suppression model” (RSM). According to the RSM, individual females adaptively suppress their reproductive functioning under conditions of social or physiological stress. From this perspective, mild anorexia is viewed as an adaptive response to modern conditions; more severe anorexia is viewed as an adaptation gone awry. Previous models have not, however, examined the full richness of the RSM. Specifically, Wasser and Barash documented not only self-imposed reproductive suppression, but (...) also manipulative reproductive suppression of subordinate females by dominants. I propose that the modern “epidemic” of anorexia is explained neither by adaptive self-suppression nor by environmental mismatch (an adaptation gone awry); I propose that the “epidemic” levels of anorexia seen in modern western society are a direct consequence of intrasexual competition, the scope of which has been enhanced by the power and reach of modern communications media. According to this perspective, anorexia, even in its mild forms, is a manipulative strategy imposed on subordinates by dominants. Anorexia is, in both senses, a “losing” strategy. (shrink)

Females make large investments in their children and compete among themselves to establish and maintain privileged relationships with male allies who demonstrate both an ability and a willingness to provide fitness-enhancing advantages. Various “strategies” and their more numerous, associated “tactics” are utilized in the competition. Alleged strategies include using sexuality, producing offspring, assisting the male in his own intrasexual contests, and harassing female competitors. The strategies in question are documented in multiple primate species, including humans living in various times (...) and places. Some variables are discussed that influence the degree to which human females rely upon them. (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)

Secular change in sex ratios is examined in relation to experience in the family. Two theoretical perspectives are outlined: Guttentag and Secord’s (1983) adaptation of social exchange theory, and sexual selection theory. Because of large-scale change in number of births and typical age differentials between men and women at marriage, low sex ratios at couple formation ages existed in the U.S. between 1965 and the early 1980s. The currently high sex ratios, however, will persist until the end of the (...) century. High sex ratios appear to be associated with lower divorce rates, male commitment to careers that promise economic rewards, male willingness to engage in child care, higher fertility, and higher rates of sexual violence. Sexual selection theory calls attention to intrasexual competition in the numerically larger sex. (shrink)

Sex- and age-specific rates of killing unrelated persons of one’s own sex were computed for Canada (1974–1983), England/Wales (1977–1986), Chicago (1965–1981), and Detroit (1972) from census information and data archives of all homicides known to police. Patterns in relation to sex and age were virtually identical among the four samples, although the rates varied enormously (from 3.7 per million citizens per annum in England/Wales to 216.3 in Detroit). Men’s marital status was related to the probability of committing a same-sex, nonrelative (...) homicide, but age effects remained conspicuous when married and unmarried men were distinguished.These findings and the treatment of age and sex effects by criminologists are discussed in the light of contemporary evolutionary psychological models of sex differences and life-span development. Same-sex homicides in which killer and victim are unrelated can be interpreted as an assay of competitive conflict. In every human society for which relevant information exists, men kill one another vastly more often than do women. Lethal interpersonal competition is especially prevalent among young men, which accords with many other aspects of life-span development in suggesting that sexual selection has maximized male competitive prowess and inclination in young adulthood. (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)

Fighting ability, although recognized as fundamental to intrasexual competition in many nonhuman species, has received little attention as an explanatory variable in the social sciences. Multiple lines of evidence from archaeology, criminology, anthropology, physiology, and psychology suggest that fighting ability was a crucial aspect of intrasexual competition for ancestral human males, and this has contributed to the evolution of numerous physical and psychological sex differences. Because fighting ability was relevant to many domains of interaction, male psychology should have (...) evolved such that a man’s attitudes and behavioral responses are calibrated according to his formidability. Data are reviewed showing that better fighters feel entitled to better outcomes, set lower thresholds for anger/aggression, have self-favoring political attitudes, and believe more in the utility of warfare. New data are presented showing that among Hollywood actors, those selected for their physical strength (i.e., action stars) are more likely to believe in the utility of warfare. (shrink)

It has long been claimed that Homo sapiens is the only species that has language, but only recently has it been recognized that humans also have an unusual pattern of growth and development. Social mammals have two stages of pre-adult development: infancy and juvenility. Humans have two additional prolonged and pronounced life history stages: childhood, an interval of four years extending between infancy and the juvenile period that follows, and adolescence, a stage of about eight years that stretches from juvenility (...) to adulthood. We begin by reviewing the primary biological and linguistic changes occurring in each of the four pre-adult ontogenetic stages in human life history. Then we attempt to trace the evolution of childhood and juvenility in our hominin ancestors. We propose that several different forms of selection applied in infancy and childhood; and that, in adolescence, elaborated vocal behaviors played a role in courtship and intrasexual competition, enhancing fitness and ultimately integrating performative and pragmatic skills with linguistic knowledge in a broad faculty of language. A theoretical consequence of our proposal is that fossil evidence of the uniquely human stages may be used, with other findings, to date the emergence of language. If important aspects of language cannot appear until sexual maturity, as we propose, then a second consequence is that the development of language requires the whole of modern human ontogeny. Our life history model thus offers new ways of investigating, and thinking about, the evolution, development, and ultimately the nature of human language. (shrink)

At the heart of the debate between social role theorists and evolutionary psychologists is whether natural selection has designed the minds of the sexes differently to some interesting extent. In this commentary I describe the standards of evidence for both the positive and negative claims. In my opinion, Archer has met the standard for designed sex differences in intrasexual conflict.

Although moral psychologists and feminist moral theorists emphasize males’ interest in justice or fairness and females’ interest in care or empathy, recent work in evolutionary psychology links females’ interests in care and empathy for others with interests in fairness and equality. In an important work on sex differences in cognitive abilities, David Geary (1998) argues that the evolutionary mechanism of sexual selection drives the evolution of particular cognitive abilities and selection for particular interests. I mount two main challenges (...) to Geary’s claims. First, I argue that female social and intrasexual competitive environments evolve, which challenges the assumption that such environments are largely nonkin-based and characterized by reciprocity. Second, I grant Geary’s entire characterization of female environments, but argue that the natures of reciprocal relationships themselves do not require and may not select for interests in fairness and equality. This analysis not only challenges claims regarding sex differences in moral interests, but also suggests the need for a diachronic model of male and female social and intrasexual competitive environments. In addition, I propose a return to Trivers’s (1971) focus on the suite of emotions underlying reciprocal altruism as properties and features of individuals as fodder for selection. (shrink)

The reductionistic vision of evolutionary theory, "the gene's eye view of evolution" is the dominant view among evolutionary biologists today. On this view, the gene is the only unit with sufficient stability to act as a unit of selection, with individuals and groups being more ephemeral units of function, but not of selection. This view is argued to be incorrect, on several grounds. The empirical and theoretical bases for the existence of higher-level units of selection are explored, (...) and alternative analyses discussed critically. The success of a multi-level selection theory demands the recognition and development of a multi-level genetics. The way to accomplish this is suggested. The genotype/phenotype distinction also requires further analysis to see how it applies at higher levels of organization. This analysis provides a way of defining genotype and phenotype for cultural evolution, and a treatment of the innate-acquired distinction which are both generalizeable to analyze problems of the nature and focus of scientific change. (shrink)

Top scholars examine the work of Donald T. Campbell, one of the first to emphasize the social structure of science.

The book presents a new way of understanding Darwinism and evolution by natural selection, combining work in biology, philosophy, and other fields.

Proceedings of the Pittsburgh Workshop in History and Philosophy of Biology, Center for Philosophy of Science, University of Pittsburgh, March 23-24 2001 Session 3: Natural Selection as a Causal Theory.

Observations with respect to the relationship between symptoms and diseases can seriously be biased by selection phenomena. This selection may occur from the general population, via consultation behavior, diagnostic and therapeutic activities of the general practitioner, and by referral.Relationships may be suggested and reproduced even if they do not exist in unselected populations, as a product of diagnostic routines. Correction for selection bias can only be achieved by choosing proper comparison groups. While this can be done in (...) a general practice setting, this is almost impossible after referral, as is demonstrated in this paper. Surprisingly, the most unbiased estimation of the relationship between symptoms and diseases after referral can be made from patient groups that are referred for reason unrelated to the disease under study. (shrink)

Human cooperation is highly unusual. We live in large groups composed mostly of non-relatives. Evolutionists have proposed a number of explanations for this pattern, including cultural group selection and extensions of more general processes such as reciprocity, kin selection, and multi-level selection acting on genes. Evolutionary processes are consilient; they affect several different empirical domains, such as patterns of behavior and the proximal drivers of that behavior. In this target article, we sketch the evidence from five domains (...) that bear on the explanatory adequacy of cultural group selection and competing hypotheses to explain human cooperation. Does cultural transmission constitute an inheritance system that can evolve in a Darwinian fashion? Are the norms that underpin institutions among the cultural traits so transmitted? Do we observe sufficient variation at the level of groups of considerable size for group selection to be a plausible process? Do human groups compete, and do success and failure in competition depend upon cultural variation? Do we observe adaptations for cooperation in humans that most plausibly arose by cultural group selection? If the answer to one of these questions is “no,” then we must look to other hypotheses. We present evidence, including quantitative evidence, that the answer to all of the questions is “yes” and argue that we must take the cultural group selection hypothesis seriously. If culturally transmitted systems of rules (institutions) that limit individual deviance organize cooperation in human societies, then it is not clear that any extant alternative to cultural group selection can be a complete explanation. (shrink)

Recent discussions in the philosophy of biology have brought into question some fundamental assumptions regarding evolutionary processes, natural selection in particular. Some authors argue that natural selection is nothing but a population-level, statistical consequence of lower-level events (Matthen and Ariew [2002]; Walsh et al. [2002]). On this view, natural selection itself does not involve forces. Other authors reject this purely statistical, population-level account for an individual-level, causal account of natural selection (Bouchard and Rosenberg [2004]). I argue (...) that each of these positions is right in one way, but wrong in another; natural selection indeed takes place at the level of populations, but it is a causal process nonetheless. (shrink)

The concept of fitness has generated a lot of discussion in philosophy of biology. There is, however, relative agreement about the need to distinguish at least two uses of the term: ecological fitness on the one hand, and population genetics fitness on the other. The goal of this paper is to give an explication of the concept of ecological fitness by providing a reconstruction of the theory of natural selection in which this concept was framed, that is, based on (...) the way the theory was put to use in Darwin’s main texts. I will contend that this reconstruction enables us to account for the current use of the theory of natural selection. The framework presupposed in the analysis will be that of metatheoretical structuralism. This framework will provide both a better understanding of the nature of ecological fitness and a more complete reconstruction of the theory. In particular, it will provide what I think is a better way of understanding how the concept of fitness is applied through heterogeneous cases. One of the major advantages of my way of thinking about natural selection theory is that it would not have the peculiar metatheoretical status that it has in other available views. I will argue that in order to achieve these goals it is necessary to make several concepts explicit, concepts that are frequently omitted in usual reconstructions. (shrink)

Most biologists and some cognitive scientists have independently reached the conclusion that there is no such thing as learning in the traditional “instructive‘ sense. This is, admittedly, a somewhat extreme thesis, but I defend it herein the light of data and theories jointly extracted from biology, especially from evolutionary theory and immunology, and from modern generative grammar. I also point out that the general demise of learning is uncontroversial in the biological sciences, while a similar consensus has not yet been (...) reached in psychology and in linguistics at large. Since many arguments presently offered in defense of learning and in defense of “general intelligence‘ are often based on a distorted picture of human biological evolution, I devote some sections of this paper to a critique of “adaptationism,‘ providing also a sketch of a better evolutionary theory. Moreover, since certain standard arguments presented today as “knock-down‘ in psychology, in linguistics and in artificial intelligence are a perfect replica of those once voiced by biologists in favor of instruction and against selection, I capitalize on these errors of the past to draw some lessons for the present and for the future. (shrink)

Should nonprejudiced reproducers genetically select embryos for light skin under background conditions of racism and colourism, given that darker skin will be disadvantageous for their child? Many intuit that there are strong moral reasons not to select light skin in these contexts. I argue that existing procreative principles cannot adequately account for this judgement. Instead, I argue that a more compelling rationale for this intuition is that such selection completes an instance of race or colour injustice. Given this, I (...) propose a new, complementary principle—Procreative Justice—which holds that reproducers have strong pro tanto moral reasons to avoid completing race and colour injustices via their selection choices. While these reasons may be overridden by competing considerations, they nonetheless continue to exert normative force. (shrink)

A deflationary perspective on theories of cultural evolution, in particular dual-inheritance theory, has recently been proposed by Lewens. On this ‘pop-culture’ analysis, dual-inheritance theorists apply population thinking to cultural phenomena, without claiming that cultural items evolve by natural selection. This paper argues against this pop-culture analysis of dual-inheritance theory. First, it focuses on recent dual-inheritance models of specific patterns of cultural change. These models exemplify population thinking without a commitment to natural selection of cultural items. There are grounds, (...) however, for doubting the added explanatory value of the models in their disciplinary context—and thus grounds for engaging in other potentially explanatory projects based on dual-inheritance theory. One such project is suggested by advocates of the theory. Some of the motivational narratives that they offer can be interpreted as setting up an adaptationist project with regard to cumulative change in cultural items. We develop this interpretation here. On it, dual-inheritance theory features two interrelated selection processes, one on the level of genetically inherited learning mechanisms, another on the level of the cultural items transmitted through these mechanisms. This interpretation identifies a need for further modelling efforts, but also offers scope for enhancing the explanatory power of dual-inheritance theory. (shrink)

Studies of group selection have been done with both natural and manipulated populations using plants, insects and birds. Group selection occurred in all studies and often the strength of group selection was equal to that of individual selection. Laboratory selection experiments resulted in the opposite response to individual selection than that predicted. Selection with plants for high leaf area resulted in plants with smaller leaf area and selection for high emigration rate in (...) beetles produced lines with lower rates. The selected traits included interactions among individuals. Theoretical studies have shown that genetically based interactions among individuals can interfere with individual selection. Evolution can be partitioned into selection and the response to selection. A response to selection requires genetic variation. Properties of group genetic structure for the natural populations are discussed. The experimental populations had controlled group structure and demonstrate that populations can respond to group selection under some genetic structures. (shrink)

This is the first of a two-part essay on the history of debates concerning the creativity of natural selection, from Darwin through the evolutionary synthesis and up to the present. Here I focus on the mid-late nineteenth century to the early twentieth, with special emphasis on early Darwinism and its critics, the self-styled “mutationists.” The second part focuses on the evolutionary synthesis and some of its critics, especially the “neutralists” and “neo-mutationists.” Like Stephen Gould, I consider the creativity of (...) natural selection to be a key component of what has traditionally counted as “Darwinism.” I argue that the creativity of natural selection is best understood in terms of selection initiating evolutionary change, and selection being responsible for the presence of the variation it acts upon, for example by directing the course of variation. I consider the respects in which both of these claims sound non-Darwinian, even though they have long been understood by supporters and critics alike to be virtually constitutive of Darwinism. (shrink)

Many people have argued that the evolution of the human language faculty cannot be explained by Darwinian natural selection. Chomsky and Gould have suggested that language may have evolved as the by-product of selection for other abilities or as a consequence of as-yet unknown laws of growth and form. Others have argued that a biological specialization for grammar is incompatible with every tenet of Darwinian theory – that it shows no genetic variation, could not exist in any intermediate (...) forms, confers no selective advantage, and would require more evolutionary time and genomic space than is available. We examine these arguments and show that they depend on inaccurate assumptions about biology or language or both. Evolutionary theory offers clear criteria for when a trait should be attributed to natural selection: complex design for some function, and the absence of alternative processes capable of explaining such complexity. Human language meets these criteria: Grammar is a complex mechanism tailored to the transmission of propositional structures through a serial interface. Autonomous and arbitrary grammatical phenomena have been offered as counterexamples to the position that language is an adaptation, but this reasoning is unsound: Communication protocols depend on arbitrary conventions that are adaptive as long as they are shared. Consequently, language acquisition in the child should systematically differ from language evolution in the species, and attempts to analogize them are misleading. Reviewing other arguments and data, we conclude that there is every reason to believe that a specialization for grammar evolved by a conventional neo-Darwinian process. (shrink)

ORIGIN OF SPECIES. INTRODUCTION. When on board HMS 'Beagle,' as naturalist, I was ranch struck with certain facts in the distribution of the organic beings ...

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)

Within a laboratory experiment we investigate a principal-agent game in which agents may, first, self-select into a group task (GT) or an individual task (IT) and, second, choose work effort. In their choices of task and effort the agents have to consider pay contracts for both tasks as offered by the principal. The rational solution of the game implies that contract design may not induce agents to select GT and provide positive effort in GT. Furthermore it predicts equal behavior of (...) agents with different productivities. In contrast, considerations of trust, reciprocity and cooperation – the social-emotional model of behavior – suggest that contract design can influence the agents’ willingness to join groups and provide effort. We analyze the data by applying a two-step regression model (multinomial logit and tobit) and find that counter to the rational solution, contract design does influence both, task selection and effort choice. The principal can increase participation in work groups and can positively influence group performance. Larger payment increases the share of socially motivated agents in work groups. The selection effect is larger than the motivation effect. (shrink)

This paper provides a new approach to inference to the best explanation based on a new coherence measure for comparing how well hypotheses explain the evidence. It addresses a number of criticisms of the use of probabilistic measures in this context by Clark Glymour, including limitations of earlier work on IBE. Computer experiments are used to show that the new approach finds the truth with a high degree of accuracy in hypothesis selection tasks and that in some cases its (...) accuracy is greater than hypothesis selection based on maximizing posterior probability. Hence, by overcoming some of the problems with the previous approach, this work provides a more adequate defence of IBE and suggests that IBE not only tracks truth but also has practical advantages over the previous approach. Applications of the new approach to parameter estimation and model selection are also explored. (shrink)

This article evaluates various aspects of the selection interview in terms of the major principles of business ethics. It looks at both interviewer and interviewee behavior and examines the ethical questions that arise around five key themes: Preparation for the interview; Openness, disclosure and the invasion of privacy; Honesty and impression management; Power relationships in the interview; The use of interview information in decision making. It is argued that clear guidelines for ethical behavior in the interview are needed and (...) would actually serve to increase the effectiveness of the method. Various topics that require empirical investigation are identified, and some parallels drawn with research on other assessment methods. (shrink)

In the previous issue of Ethical Perspectives David Heyd defends the permissibility of sex selection for non-medical reasons. He tries to show that there is nothing inherently wrong with this practice and that allowing it does not lead to undesirable consequences. There are several difficulties with his analysis, but the main objection is that it ultimately relies on a crude form of utilitarianism. Along with some critical comments on his article, we provide ethical arguments in support of the intuitive (...) condemnation of sex selection for non-medical reasons. (shrink)

This report details experimental results of using stochastic disambiguation models for parsing sentences from the Redwoods treebank (Oepen et al., 2002). The goals of this paper are two-fold: (i) to report accuracy results on the more highly ambiguous latest version of the treebank, as compared to already published results achieved by the same stochastic models on a previous version of the corpus, and (ii) to present some newly developed models using features from the HPSG signs, as well as the MRS (...) dependency graphs. (shrink)