The various behavioral disciplines model human behavior in distinct and incompatible ways. Yet, recent theoretical and empirical developments have created the conditions for rendering coherent the areas of overlap of the various behavioral disciplines. The analytical tools deployed in this task incorporate core principles from several behavioral disciplines. The proposed framework recognizes evolutionary theory, covering both genetic and cultural evolution, as the integrating principle of behavioral science. Moreover, if decision theory and game theory are broadened to encompass other-regarding preferences, they (...) become capable of modeling all aspects of decision making, including those normally considered “psychological,” “sociological,” or “anthropological.” The mind as a decision-making organ then becomes the organizing principle of psychology. (Published Online April 27 2007) Key Words: behavioral game theory; behavioral science; evolutionary theory; experimental psychology; gene-culture coevolution; rational actor model; socialization. (shrink)

Summary: The evolution of complex societies began when agricultural subsistence systems raised human population densities to levels that would support large scale cooperation, and division of labor. All agricultural origins sequences postdate 11,500 years ago probably because late Pleistocene climates we extremely variable, dry, and the atmosphere was low in carbon dioxide. Under such conditions, agriculture was likely impossible. However, the tribal scale societies of the Pleistocene did acquire, by geneculture coevolution, tribal social instincts that simultaneously enable and constrain the (...) evolution of complex societies. Once agriculture became possible, a competitive ratchet drove further improvements in subsistence and in scale of social organization . Those societies that grew and became better organized were advantaged in individual wealth and economic and military power, and tended to conquer, absorb, or be imitated by smaller and less well organized societies. Internal competitors for power espousing useful social innovations could deliver improved returns when their quest was successful. Notwithstanding the ratchet, social complexity increased only slowly in the first half of the Holocene and even afterwards few periods except the past two centuries saw changes that were dramatic on the scale of individual lifetimes. We attempt a taxonomy of the processes that regulate rates of institutional evolution, cause reversals of complexity against the ratchet, and impose historical contingency on institutional evolution. (shrink)

Group beneficial norms are common in human societies. The persistence of such norms is consistent with evolutionary game theory, but existing models do not provide a plausible explanation for why they are common. We show that when a model of imitation used to derive replicator dynamics in isolated populations is generalized to allow for population structure, group beneficial norms can spread rapidly under plausible conditions. We also show that this mechanism allows recombination of different group beneficial norms arising in..

In this book, I make use of an idea from economics to suggest how noble human tendencies might not only have survived the ruthless pressures of the material world, but actually have been nurtured by them.

Comparing food taboos across 78 cultures, this paper demonstrates that meat, though a prized food, is also the principal target of proscriptions. Reviewing existing explanations of taboos, we find that both functionalist and symbolic approaches fail to account for meat's cross-cultural centrality and do not reflect experience-near aspects of food taboos, principal among which is disgust. Adopting an evolutionary approach to the mind, this paper presents an alternative to existing explanations of food taboos. Consistent with the attendant risk of pathogen (...) transmission, meat has special salience as a stimulus for humans, as animal products are stronger elicitors of disgust and aversion than plant products. We identify three psychosocial processes, socially-mediated ingestive conditioning, egocentric empathy, and normative moralization, each of which likely plays a role in transforming individual disgust responses and conditioned food aversions into institutionalized food taboos. (shrink)

Two kinds of factors set the tempo and direction of organic and cultural evolution, those external to biotic evolutionary process, such as changes in the earth’s physical and chemical environments, and those internal to it, such as the time required for chance factors to lead lineages across adaptive valleys to a new niche space (Valentine 1985). The relative importance of these two sorts of processes is widely debated. Valentine (1973) argued that marine invertebrate diversity patterns responded to seafloor spreading as (...) this process generated more or less niche space. He suggested that natural selection is a powerful force and that earth’s biota are in near equilibrium with the niches available on the geological time scale. Walker and Valentine (1984) modeled the evolution of species assuming a logistic speciation rate limited by internal factors and a diversity-independent death rate caused by ongoing environmental change. Fitting this model to the observed evolution of shelled marine invertebrates suggests that the lag between extinctions and the evolution of new species leaves perhaps 30% of ecological niches unfilled. In this model, the biota lag environmental change by perhaps a few million years. However, as Valentine (1985) notes, if adaptive landscapes have whole suites of niches protected by deep maladaptive valleys, the waiting time for some pioneering species to cross the divide may be very long, generating the rare events that set new body plans and generate major adaptive radiations. Eldredge and Gould (1972) and Gould (2002) championed the idea that internal processes such as genetic and developmental constraints, coupled with the complexity of the adaptive landscape, resulted in a highly historically contingent evolutionary process. On Gould’s account, most of the history of life had to do not with a relatively close tracking of a changing environment but with the halting evolutionary exploration a deeply fissured niche space, mostly by rapid bursts of evolution as a fissure was crossed, followed by long periods of stasis.. (shrink)

Unobservable properties that are specific to individuals, such as their proper names, can only be known by people who are familiar with those individuals. Do young children utilize this “familiarity principle” when learning language? Experiment 1 tested whether forty-eight 2- to 4-year-old children were able to determine the referent of a proper name such as “Jessie” based on the knowledge that the speaker was familiar with one individual but unfamiliar with the other. Even 2-year-olds successfully identified Jessie as the individual (...) with whom the speaker was familiar. Experiment 2 examined whether children appreciate this principle at a general level, as do adults, or whether this knowledge may be specific to certain word-learning situations. To test this, forty-eight 3- to 5-year-old children were given the converse of the task in Experiment 1—they were asked to determine the individual with whom the speaker was familiar based on the speaker’s knowledge of an individual’s proper name. Only 5-year-olds reliably succeeded at this task, suggesting that a general understanding of the familiarity principle is a relatively late developmental accomplishment. (shrink)

Human migration is nonrandom. In small scale societies of the past, and in the modern world, people tend to move to wealthier, safer, and more just societies from poorer, more violent, less just societies. If immigrants are assimilated, such nonrandom migration can increase the occurrence of culturally transmitted beliefs, values, and institutions that cause societies to be attractive to immigrants. Here we describe and analyze a simple model of this process. This model suggests that long run outcomes depend on the (...) relative strength of migration and local adaptation. When local adaption is strong enough to preserve cultural variation among groups, cultural variants that make societies attractive always predominate, but never drive alternative variants to extinction. When migration predominates, outcomes depend both on the relative attractiveness of alternative variants and on the initial sizes of societies that provide and receive immigrants. (shrink)

What leads humans to divide the social world into groups, preferring their own group and disfavoring others? Experiments with infants and young children suggest these tendencies are based on predispo- sitions that emerge early in life and depend, in part, on natural language. Young infants prefer to look at a person who previously spoke their native language. Older infants preferentially accept toys from native-language speakers, and preschool children preferentially select native-language speakers as friends. Variations in accent are sufficient to evoke (...) these social preferences, which are observed in infants before they produce or comprehend speech and are exhibited by children even when they comprehend the foreign-accented speech. Early-developing preferences for native-language speakers may serve as a foundation for later-developing preferences and conflicts among social groups. (shrink)