Prejudice from an evolutionary perspective

Prejudice can be considered from an evolutionary perspective. Evolutionary psychologists posit that our psychology, e.g. emotion and cognition, has not been uniquely isolated from the forces of evolution. Although there is psychological variation among individuals, the majority of our psychological mechanisms should be adaptations designed specifically to solve recurrent problems, many of which were social in nature, in our evolutionary history. To balance the costs and benefits of sociality we must be able to recognize and functionally respond to threats and opportunities (see James J. Gibson), and our errors in judgment should be biased toward minimizing costs to reproductive fitness. Our implicit responses to others result from the activation of functionally specific adaptations to motivate action, either to take advantage of opportunities, avoid or confront threats. The valence—positive or negative—of those responses can be measured using implicit association tests. Unconscious, negative reactions are often referred to as prejudice, but these prejudices are much more contextually rich than simple, positive or negative affect, and often involve discrete emotions, which likely represent unique adaptations to motivate functionally distinct actions. Our evolved biases toward minimizing fitness costs may have implications for the function and/or malfunction of stigma, prejudice, and discriminatory behavior in post-industrial societies. Some common biases (sex, age, race) are discussed.
Recognizing threats and opportunities.
According to James J. Gibson, a founder of ecological psychology, humans perceive their environment in terms of affordances. Different animals and objects afford different actions. These affordances are context-dependent. For instance, the same trait may afford both costs and benefits depending on the bearer, the social and environmental contexts, and the relative affordances or vulnerabilities of the perceiver. Although affordances are relative, they are invariant given the same context and provide strong selective pressure for adaptations to recognize and functionally respond to both threats and opportunities. For a review of the application of ecological theory to social perception, see McArthur and Baron (1983).
Error management theory and the smoke detector principle.
In their Error Management Theory (see also Adaptive Bias), Martie Haselton and David Buss suggested that judgments about opportunities and threats, in cases of uncertainty, should consistently err toward minimizing potential costs to reproductive fitness. Smoke detectors have often been used as an analogy for how threat mitigating adaptations should function. Smoke detectors are designed to be overly-sensitive to the presence of smoke so that they don’t fail to respond in case of an actual fire. For this reason, they often give false alarms. However, if smoke detectors are too sensitive, we are likely to either turn them off or become desensitized to their warnings. Adaptations should function similarly, erring on the side of caution. False alarms may be common, but overall costs are minimized.
Evolved prejudice.
Prejudice is often associated with discrimination, which, in the colloquial sense, means the active and explicit exclusion and derogation of minority groups based on preconceived and unfounded judgments. This type of discrimination certainly exists, but it is in no way justified by the presence of evolved prejudices. However, discriminate sociality is an integral part of group living, as different individuals afford different threats and opportunities. For instance, indiscriminate cooperation is inherently unstable because it is easily invaded by cheats and free-riders. Thus, cooperative groups cannot exist without mechanisms to recognize and punish non-cooperators. Indiscriminate association in other domains, such as pathogen avoidance and intergroup conflict, has similar consequences, and indiscriminate social actors will generally have lower fitness than those who are able to respond functionally to the affordances of others.
Emotion and prejudice.
In 1872, Charles Darwin published The Expression of the Emotions in Man and Animals and theorized that humans had universal emotions that functioned to motivate specific behaviors. Paul Ekman, in 1971, published cross-cultural research supporting Darwin’s predictions. People in both pre-literate and literate societies recognized distinct emotions (fear, anger, disgust, sadness, happiness, surprise), which Ekman suggested were universal and socially functional adaptations. Cottrell and Neuberg (2005) found that threats are functionally different for different individuals and predictably activate different emotions, which motivate unique behavioral responses.
Common sociofunctional prejudice.
Since affordances are relative, and threats are often functionally distinct (e.g., threats of violence, disease, non-cooperation, threats to the functional efficiency of groups), these different types of threats likely provided distinct evolutionary pressures and activate different emotions, which in turn motivate different behaviors. Likewise, these functionally unique adaptations should be activated by different cues for different people, as threats are not universal. Since false positives are costly, adaptations for threat avoidance, aversion, or confrontation should be differentially activated based on threat vulnerability. Much research has focused on the functional flexibility of prejudice. Selected examples are shown below.
Sexism.
Haselton and Buss extended Robert Trivers parental investment theory to predict intrasexual mind-reading errors associated with female sexual intent and male commitment intent. Males and females have inherently different costs and benefits associated with parental investment because of their different physiology. Women lose reproductive opportunities and incur large energy costs during gestation. However, women are assured of parentage and can afford to invest more in individual offspring than males, for whom paternity is uncertain. Thus, women should be choosy about potential mates, balancing the benefits of good genes and potential paternal investment. Men, however, should act to minimize the costs associated with paternity uncertainty by maximizing mating opportunities. Haselton and Buss found that women, on average, underestimated men's commitment intent, and men, on average, overestimated women's sexual intent. These implicit biases may underpin common intersexual prejudice: sexism. The authors suggested that these errors (prejudices) should be moderated by relative mate value, but little to no research has explored these predictions.
Ageism.
Prejudices toward the elderly are common and may arise from perceptions of functionally distinct threats, e.g. disease, group efficiency. Duncan and Schaller found that individuals who felt more vulnerable to disease, both chronically and in experimentally primed conditions, were more likely to have implicit biases against the elderly, but these effects were moderated by cultural experience.
Racism and xenophobia.
Humans likely did not frequently encounter different races during evolutionary history. Thus, we do not have adaptations specific to race. However, we did have recurrent encounters with groups that were not our own - out-group - and these encounters likely had different consequences for men and women, specifically with respect to out-group men. Carlos Navarrete and colleagues found that race biases against out-group males were functionally distinct for in-group men and women. Men's biases were motivated by aggression and social dominance, whereas women's biases were consistently motivated by fear of sexual coercion. These findings are consistent with the predicted differential selective pressures on men and women, imposed by outgroup men. For women, these biases should be strongest when threats of coercion have the greatest potential fitness costs. Indeed, Navarrete and colleagues found that race bias increased with increased conception risk. However "Racism" on its face is not merely emotional nor based solely on preconception; many of the biases felt by both the in-group and out-group are strongly predicated upon established cultural social/societal norms.
Flexible in-group categorization and prejudice.
When we encounter people we often categorize them by their race and this has implications for the way we interact with them. However, research suggests that race categorization is either absent or reduced when more motivationally relevant grouping cues are apparent. For instance, Kurzban, Tooby and Cosmides found that when coalitional information did not align with race, encoding based on race was either reduced or absent, which suggests that prejudices associated with race co-opt adaptations that respond to cues of coalitional membership and mitigate threats presented by members of out-groups. Coalitional flexibility may have implications for managing functionally distinct prejudices, many of which may be activated by apparent out-group status, cues of which may be frequency dependent and thus, altered by coalitional composition.