Human suicide presents a fundamental problem for the scientific analysis of behavior. This problem has been neither appreciated nor confronted by research and theory. Almost all other behavior exhibited by humans and nonhumans can be viewed as supporting the behaving organism's biological fitness and advancing the welfare of its genes. Yet suicide acts against these ends, and does so more directly and unequivocally than any other form of maladaptive behavior. Four heuristic models are presented here to account for suicide in (...) an evolutionary and sociobiological framework. The first model attributes suicide to the extraordinary development of learning and cultural evolution in the human species. Learning may make human behavior so independent of biological constraints that it can occasionally assume a form entirely contrary to the principles of biological evolution. The second model attributes suicide to a breakdown of adaptive mechanisms in extremely stressful novel environments. The third model involves kin and group selection, arguing that in limited circumstances suicide may occur because of beneficial effects it has on other, surviving individuals who share the suicidal individual's genes. The last model suggests that suicide should be tolerated by evolution when it has no effect on the gene pool. This model holds particular promise in accounting for aspects of suicide not attributable to culture. The evidence indicates that suicide is most common in individuals who are unlikely to reproduce and unable to engage in productive activity; such individuals are least capable of promoting their genes. A complete explanation of suicide may derive only from an analysis of its biological significance. (shrink)

Patterns in the data on human sexuality support the hypothesis that the bases of sexual emotions are products of natural selection. Most generally, the universal existence of laws, rules, and gossip about sex, the pervasive interest in other people's sex lives, the widespread seeking of privacy for sexual intercourse, and the secrecy that normally permeates sexual conduct imply a history of reproductive competition. More specifically, the typical differences between men and women in sexual feelings can be explained most parsimoniously as (...) resulting from the extraordinarily different reproductive opportunities and constraints males and females normally encountered during the course of evolutionary history. Men are more likely than women to desire multiple mates; to desire a variety of sexual partners; to experience sexual jealousy of a spouse irrespective of specific circumstances; to be sexually aroused by the sight of a member of the other sex; to experience an autonomous desire for sexual intercourse; and to evaluate sexual desirability primarily on the bases of physical appearance and youth.The evolutionary causes of human sexuality have been obscured by attempts to find harmony in natural creative processes and human social life and to view sex differences as complementary. The human female's capacity for orgasm and the loss of estrus, for example, have been persistently interpreted as marriage-maintaining adaptations. Available evidence is more consistent with the view that few sex differences in sexuality are complementary, that many aspects of sexuality undermine marriage, and that sexuality is less a unifying than a divisive force in human affairs. (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)

Classifying is a fundamental operation in the acquisition of knowledge. Taxonomic theory can help students of cognition, evolutionary psychology, ethology, anatomy, and sociobiology to avoid serious mistakes, both practical and theoretical. More positively, it helps in generating hypotheses useful to a wide range of disciplines. Composite wholes, such as species and societies, are “individuals” in the logical sense, and should not be treated as if they were classes. A group of analogous features is a natural kind, but a group of (...) homologous features is not. Imposing hypotheses justified only on the basis of nominalist, realist, phenomenalist, or conceptualist metaphysics upon the neurophysiology of organisms or upon the causes of behavior exemplifies the “psychologist's fallacy” of William James. Levels should be distinguished from their members and from classes of levels, and the ontological status of entities ranked at levels should be made clear. It is important not to confuse such categories as substance and process with one another. Several genetical terms, such as “gene” and chromosome,” are even more equivocal than has been realized. Discussions about units of selection, behavior, and thinking suffer from the ambiguity of a “unit of” an entity. An important source of misunderstanding about natural selection is the habit of treating it as an “agent”: in an important sense, natural selection does not “act” at all. (shrink)

Tomasello, Kruger & Ratner deserve congratulations for their well-reasoned ideas on the development of cultural learning. Their arguments are generally convincing, perhaps because their distinctions and developmental relations among types of cultural learning and agency mirror concepts of my own.

Human behavior is the joint product of (i) contingencies of survival responsible for natural selection, and (ii) contingencies of reinforcement responsible for the repertoires of individuals, including (iii) the special contingencies maintained by an evolved social environment. Selection by consequences is a causal mode found only in living things, or in machines made by living things. It was first recognized in natural selection: Reproduction, a first consequence, led to the evolution of cells, organs, and organisms reproducing themselves under increasingly diverse (...) conditions. The behavior functioned well, however, only under conditions similar to those under which it was selected.Reproduction under a wider range of consequences became possible with the evolution of processes through which organisms acquired behavior appropriate to novel environments. One of these, operant conditioning, is a second kind of selection by consequences: New responses could be strengthened by events which followed them. When the selecting consequences are the same, operant conditioning and natural selection work together redundantly. But because a species which quickly acquires behavior appropriate to an environment has less need for an innate repertoire, operant conditioning could replace as well as supplement the natural selection of behavior.Social behavior is within easy range of natural selection, because other members are one of the most stable features of the environment of a species. The human species presumably became more social when its vocal musculature came under operant control. Verbal behavior greatly increased the importance of a third kind of selection by consequences, the evolution of social environments or cultures. The effect on the group, and not the reinforcing consequences for individual members, is responsible for the evolution of culture. (shrink)

Most definitions of radical emergentism characterize it epistemologically. This leads to misunderstandings and makes it hard to assess the doctrine's metaphysical worth. This paper puts forward purely metaphysical characterizations of emergentism and property emergence. It explores the nature of the necessitation relation between base and emergent and argues that emergentism entails a Humean account of causation and related relations. Then it presents arguments against emergentism, both as a wider metaphysic and as an account of consciousness. These maintain that emergentism makes (...) implausible claims about how the world works. The paper also stresses the doctrine's contemporary relevance: most current property dualists endorse views effectively identical to classical emergentism less its historical commitment to novel emergent forces. (shrink)

Inclusive fitness theory provides conditions for the evolutionary success of a gene. These conditions ensure that the gene is selfish in the sense of Dawkins (The selfish gene, Oxford University Press, Oxford, 1976): genes do not and cannot sacrifice their own fitness on behalf of the reproductive population. Therefore, while natural selection explains the appearance of design in the living world (Dawkins in The blind watchmaker: why the evidence of evolution reveals a universe without design, W. W. Norton, New York, (...) 1996), inclusive fitness theory does not explain how. Indeed, Hamilton’s rule is equally compatible with the evolutionary success of prosocial altruistic genes and antisocial predatory genes, whereas only the former, which account for the appearance of design, predominate in successful organisms. Inclusive fitness theory, however, permits a formulation of the central problem of sociobiology in a particularly poignant form: how do interactions among loci induce utterly selfish genes to collaborate, or to predispose their carriers to collaborate, in promoting the fitness of their carriers? Inclusive fitness theory, because it abstracts from synergistic interactions among loci, does not answer this question. Fitness-enhancing collaboration among loci in the genome of a reproductive population requires suppressing alleles that decrease, and promoting alleles that increase the fitness of its carriers. Suppression and promotion are effected by regulatory networks of genes, each of which is itself utterly selfish. This implies that genes, and a fortiori individuals in a social species, do not maximize inclusive fitness but rather interact strategically in complex ways. It is the task of sociobiology to model these complex interactions. (shrink)

In a laboratory experiment, we use a public goods game to examine the hypothesis that human subjects use an involuntary eye-detector mechanism for evaluating the level of privacy. Half of our subjects are “watched” by images of a robot presented on their computer screen. The robot—named Kismet and invented at MIT—is constructed from objects that are obviously not human with the exception of its eyes. In our experiment, Kismet produces a significant difference in behavior that is not consistent with existing (...) economic models of preferences, either self- or other-regarding. Subjects who are “watched” by Kismet contribute 29% more to the public good than do subjects in the same setting without Kismet. (shrink)

Empirical tests described in this article support hypotheses derived from evolutionary theory on the perceptions of literary characters. The proper and dark heroes in British Romantic literature of the late eighteenth and early nineteenth centuries respectively represent long-term and short-term mating strategies. Recent studies indicate that for long-term relationships, women seek partners with the ability and willingness to sustain paternal investment in extended relationships. For short-term relationships, women choose partners whose features indicate high genetic quality. In hypothetical scenarios, females preferred (...) proper heroes for long-term relationships. The shorter the relationship under consideration, the more likely women were to choose dark heroes as partners. (shrink)

Trivers’s theory of parental investment suggests that adults should decide whether or not to invest in a given infant using a cost-benefit analysis. To make the best investment decision, adults should seek as much relevant information as possible. Infant facial cues may serve to provide information and evoke feelings of parental care in adults. Four specific infant facial cues were investigated: resemblance (as a proxy for kinship), health, happiness, and cuteness. It was predicted that these cues would influence feelings of (...) parental care for both sexes, but that resemblance would be more important for men than women because of the importance of paternity uncertainty in the ancestral environment. Seventy-six men and 76 women participated in a hypothetical adoption task in which they made judgments of infant faces. Average zero-order, partial, and component score correlations all revealed that men placed primary emphasis on cues of resemblance, while women placed primary emphasis on cues of health and cuteness (cues of infant quality). The correlations also showed that men placed a significantly greater emphasis on cues of resemblance than did women. (shrink)