Evolutionary Social Psychology Research Paper

Although people vary among themselves, both within and between cultures, certain regularities recur in human social interactions the world over. Members of all human groups communicate using complex spoken language, and share emotional expressions such as smiles and sneers, for example. Some social behavior patterns are unique to humans, some we share with many other species—the strong bonds between mammalian mothers and offspring, for instance. Similarly, other animals with slow-developing young often have biparental care of offspring, and other animals that live in small groups tend to have dominance hierarchies.

1. General Principles Applying Across Species

Evolutionary theorists search for principles applying across animal species. Differential parental investment refers to differences between parents in the amount of resources invested in offspring (Trivers 1972). As either sex increases investment in offspring, they become more selective about choosing mates. Members of the other sex consequently compete to be chosen. In mammals, females have an initially high investment (due to internal gestation and nursing). Because females in most mammalian species contribute substantially to offspring, they are in a position to choose among males demonstrating relatively superior health, attractiveness, or dominance. Hence, mammalian males, compared to females, tend to fight more among themselves, to be physically larger, and to possess more ornaments such as antlers. Sexual selection occurs when features are transmitted to offspring because they confer advantages in attracting the opposite sex (as in peacocks’ feathers), or in competing with the same sex (as in rams’ horns).

A central principle is inclusive fitness maximization—the idea that animals are designed not simply to survive and produce their own offspring, but to increase the probability their genes make it into future generations. Inclusive fitness explains many instances of apparently self-sacrificing behavior in animals. Ground squirrels who spot predators are more likely to make alarm calls if neighbors are closely related (Sherman 1981). By slightly increasing their own risk, humans and other animals can gain a net genetic benefit—saving other individuals with copies of their genes.

1.1 Application To Human Social Behavior

Evolutionary theorists mine these broad principles for insights about human behavior, and to make predictions about circumstances under which people will be more or less likely to manifest aggression, altruism, or courtship behaviors. For example, men are slightly larger than women and reach reproductive maturity at a later age. Women commit substantially fewer homicides or assaults than men, and male violence is predominantly directed at other males. Across animal species, these are hallmarks of differential parental investment and polygyny. Of 849 societies in the cross-cultural area files, polygyny (one male and multiple females) was either usual or occasional in 708, polyandry (one female and multiple males) was found in only four, and the remaining 137 were exclusively monogamous (Daly and Wilson 1983). Further, the circumstances associated with these variations follow principles found in other species (Daly and Wilson 1983, Crook and Crook 1988). For example, polyandry often involves brothers (who share genetic interests) living in resource-poor environments. Steep polygyny (as in harems) is found in circumstances of relative abundance, steep social hierarchy, and occasional famine (so a female’s offspring have a better chance of surviving if she chooses an already married man from a wealthy powerful family over a single poor man). Although polygyny was an option across societies, most marriages are monogamous, because only highly successful men attracted multiple wives. Hence, ancestral males invested most of their reproductive effort in the offspring of a small number of women (often one). As a consequence, human males are selective about long-term mates, and females will compete with one another for desirable males (Buss 1999, Kenrick and Trost 1993).

2. Cross-Cultural Data

Because all human groups involve some common demands, evolutionary theorists assume that people the world over, despite cultural and ecological differences, share common human characteristics. Cross-cultural data reveal some general patterns consistent with principles of differential parental investment and sexual selection (Kenrick and Trost 1993). Adult males have killed one another many times more frequently than adult females in societies ranging from hunter-gatherers in remote jungles to urbanites in modern Asia and Europe, as far back as historical data are available (Daly and Wilson 1988). Likewise, women across societies place more emphasis than men on potential mates’ resources and status (Buss 1999).

Other data on mate selection reflect a unique feature of human biology—females reach sexual maturity earlier than males, show a fertility peak in the twenties and early thirties, and then completely cease reproduction despite many remaining years of life. Consistent with this difference in reproductive lifespan, women are attracted to mates several years older than themselves, whereas men change relative preferences as they age. Young men are attracted to women their own age or older; older men prefer women much younger than themselves (Kenrick et al. 1996). These patterns are found around the world, with somewhat stronger sex differences in societies in which women begin reproducing earlier (Kenrick and Keefe 1992).

3. Experimental Data

Evolutionary principles can be used to generate experimental predictions. Experiments are not designed to test basic assumptions about natural selection, but to use the general principles as heuristics. For example, one team of researchers used inclusive fitness theory to generate predictions about helpfulness towards individuals varying in genetic relatedness (Burnstein et al. 1994). Experimental scenarios described helping situations ranging from small errands to rescuing someone in a burning building. For everyday helping, norms of politeness buffered discrepancies based on kinship and reproductive potential (grandmother was more likely to be helped than younger sister, for example). In life or death situations, however, help was focused more on closely related individuals with high reproductive potential (younger sister compared to grandmother or cousin, for example). Another series of studies examined how sex differences in mate selection criteria affect perceptual processes related to judgments of oneself and potential mates (Gutierres et al. 1999, Kenrick et al. 1994). Women rated commitment to male partners lower after exposure to socially dominant, but not physically attractive, men, whereas men’s commitment showed the opposite effect. Conversely, women’s self-ratings of their mating desirability were diminished more by physically attractive than by socially dominant women, with men’s self-ratings showing the opposite effect (diminished by dominant, but not physically attractive men).

4. History And Future Directions

McDougall’s (1908) Social Psychology assumed human social ‘instincts.’ The position was much misunderstood and abandoned without an empirical legacy. Decades later, European ethologists began successfully applying evolutionary models to social behaviors of nonhuman animals. In 1975, E. O. Wilson made a controversial suggestion that ‘sociobiology’ (the evolutionary analysis of animal social behavior) would eventually encompass the social sciences. This stimulated social psychologists to consider empirical applications to their field (e.g., Cunningham 1981). Part of the controversy about the approach stemmed from misunderstandings about genetic determinism. Human social behaviors vary across contexts and cultures, and social scientists assumed sociobiology implied rigid instincts insensitive to environments. Some protested that evolutionary hypotheses were untestable, or required researchers to study genetic biology or archaeology. Evolutionary theorists clarified that environmentally insensitive instincts based on deterministic genes are misconceptions, hardly relevant to invertebrates, much less to mammals (e.g., Alcock 1998, Kenrick 1995). The brains of complex animals contain not rigid programs, but environmentally sensitive psychological mechanisms (Buss and Kenrick 1998, Kenrick et al. 1998, Tooby and Cosmides 1992). Questions about testability were addressed with empirical data and competing evolutionary hypotheses (e.g., Graziano et al. 1997, Gangestad and Thornhill 1997). The position remains controversial, but has moved towards mainstream empirical science (e.g., Buss 1999, Crawford and Krebs 1998, Simpson and Kenrick 1997). Evolutionary psychologists assume the perspective could enrich research on any topic in social behavior, and that other areas of psychology including personality, psychopathology, and cognitive neuroscience are all linked by this perspective. Although the implications for mating behaviors and sex differences have been most thoroughly explored, evolutionary models have implications for understanding kinship and family relationships, intergroup relations, and social cognition. Evolutionary psychologists believe the Darwinian perspective is as relevant to the study of human beings as it has been to the study of all other living species.

Bibliography:

1. Alcock J 1998 Animal Behavior, 6th edn. Sinauer Associates, Sunderland, MA
2. Burnstein E, Crandall C, Kitayama S 1994 Some neo-Darwinian decision rules for altruism: Weighing cues for inclusive fitness as a function of the biological importance of the decision. Journal of Personality and Social Psychology 67: 773–89
3. Buss D M 1999 Evolutionary Psychology: The New Science of Mind. Allyn and Bacon, Boston, MA
4. Buss D M, Kenrick D T 1998 Evolutionary social psychology. In: Gilbert D T, Fiske S T, Lindzey G (eds.) Handbook of Social Psychology, 4th edn. McGraw-Hill, New York
5. Cosmides L, Tooby J 1992 Cognitive adaptations for social exchange. In: Barkow J H, Cosmides L, Tooby J (eds.) The Adapted Mind: Evolutionary Psychology and the Generation of Culture. Oxford University Press, New York
6. Crawford C, Krebs D L 1998 Handbook of Evolutionary Psychology: Ideas, Issues, and Applications. Erlbaum, Mahwah, NJ
7. Crook J H, Crook S J 1988 Tibetan polyandry: Problems of adaptation and fitness. In: Betzig L, Borgerhoff-Mulder M, Turke P (eds.) Human Reproductive Behaviour: A Darwinian Perspective. Cambridge University Press, Cambridge, UK
8. Cunningam M R 1981 Sociobiology as a supplementary paradigm for social psychological research. In: Wheeler L (ed.) Review of Personality & Social Psychology. Sage, Beverly Hills, CA
9. Daly M, Wilson M 1983 Sex, Evolution, and Behavior, 2nd edn. Willard Grant Press, Boston
10. Daly M, Wilson M 1988 Homicide. de Gruyter, New York
11. Daly M, Salmon C, Wilson M 1997 Kinship: The conceptual hole in psychological studies of social cognition and close relationships. In: Simpson J A, Kenrick D T (eds.) Evolutionary Social Psychology. Erlbaum, Mahwah, NJ
12. Darwin C 1872 The Expression of Emotion in Man and Animals. Murray, London
13. Gangestad S W, Thornhill R 1997 Human sexual selection and developmental stability. In: Simpson J A, Kenrick D T (eds.) Evolutionary Social Psychology. Erlbaum, Mahwah, NJ
14. Graziano W G, Jensen-Campbell L A, Todd M, Finch J F 1997 Interpersonal attraction from an evolutionary perspective: Reactions to dominant and prosocial men. In: Simpson J A, Kenrick D T (eds.) Evolutionary Social Psychology. Erlbaum, Mahwah, NJ
15. Gutierres S E, Kenrick D T, Partch J J 1999 Beauty, dominance, and the mating game: Contrast effects in self-assessment reflect gender differences in mate selection. Personality & Social Psychology Bulletin 25: 1126–34
16. Kenrick D T 1995 Evolutionary theory versus the confederacy of dunces. Psychological Inquiry 6: 56–61
17. Kenrick D T, Gabrielidis C, Keefe R C, Cornelius J S 1996 Adolescents’ age preferences for dating partners: Support for an evolutionary model of life-history strategies. Child Development 67: 1499–511
18. Kenrick D T, Keefe R C 1992 Age preferences in mates reflect sex differences in human reproductive strategies. Behavioral and Brain Sciences 15: 75–133
19. Kenrick D T, Neuberg S L, Zierk K L, Krones J M 1994 Evolution and social cognition: Contrast effects as a function of sex, dominance, and physical attractiveness. Personality & Social Psychology Bulletin 20: 210–17
20. Kenrick D T, Sadalla E K, Keefe R C 1998 Evolutionary cognitive psychology. In: Crawford C, Krebs D (eds.) Evolution and Human Behavior: Ideas, Issues, and Applications. Erlbaum, Mahwah, NJ
21. Kenrick D T, Trost M R 1993 The evolutionary perspective. In: Beall A, Sternberg R J (eds.) Perspectives on the Psychology of Gender. Guilford Press, New York
22. Sherman P W 1981 Kinship demography and Belding’s ground squirrel nepotism. Behavioral Ecology and Sociobiology 8: 251–59
23. Simpson J A, Kenrick D T (eds.) 1997 Evolutionary Social Psychology. Erlbaum, Mahwah, NJ
24. Tooby J, Cosmides L 1992 The psychological foundations of culture. In: Barkow J H, Cosmides L, Tooby J (eds.) The Adapted Mind: Evolutionary Psychology and the Generation of Culture. Oxford University Press, New York
25. Trivers R L 1972 Parental investment and sexual selection. In: Campbell B (ed.) Sexual Selection and the Descent of Man 1871–1971. Aldine, Chicago, IL
26. Wilson E O 1975 Sociobiology: The New Synthesis. Belknap Press of Harvard University Press, Cambridge, MA