Genetic similarity theory, intelligence, and human mate choice

Sex differences in human mate preferences: Evolutionary hypotheses tested in 37 cultures

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 (totalN= 10,047). 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.

Social perception of facial resemblance in humans

Two lines of reasoning predict that highly social species will have mechanisms to influence behavior toward individuals depending on their degree of relatedness. First, inclusive fitness theory leads to the prediction that organisms will preferentially help closely related kin over more distantly related individuals. Second, evaluation of the relative costs and potential benefits of inbreeding suggests that the degree of kinship should also be considered when choosing a mate. In order to behaviorally discriminate between individuals with different levels of relatedness, organisms must be able to discriminate cues of kinship. Facial resemblance is one such potential cue in humans. Computer-graphic manipulation of face images has made it possible to experimentally test hypotheses about human kin recognition by facial phenotype matching. We review recent experimental evidence that humans respond to facial resemblance in ways consistent with inclusive fitness theory and considerations of the costs of inbreeding, namely by increasing prosocial behavior and positive attributions toward self-resembling images and selectively tempering attributions of attractiveness to other-sex faces in the context of a sexual relationship.

Mate Choice and Friendship in Twins: Evidence for Genetic Similarity

This study examined the genetic and environmental contribution to people's preference for spouses and friends to be similar to themselves. In their responses to 130 personality, attitude, and demographic questions, 174 pairs of monozygotic (MZ) twins resembled each other (r= .53) more than did 148 pairs of dizygotic (DZ) twins (r= .32), 322 pairs of spouses (r= .32), and 563 pairs of best friends (r= .20). It was not previously recognized that spouses and friends are as similar as DZ twins. MZ twins also chose spouses and best friends more similar to their co-twins' friends and spouses than did DZ twins (mean rs = .22 vs. .14). The twins' preference for spouses and friends similar to themselves was about 34% due to the twins' genes, 12% due to the twins' common environment, and 54% due to the twins' unique (nonshared) environment. Similarity to partners was more pronounced on the more heritable items than the less heritable items. It is concluded that people are genetically inclined to choose as social partners those who resemble themselves at a genetic level.