Mating preferences are qualities that one desires in a romantic or sexual partner. Research across many domains, such as evolutionary biology, psychology, and anthropology, shows that humans display both widely shared (consensual) preferences – like preferences for kindness, intelligence, and health – as well as sex-differentiated preferences shaped by ancestral selection pressures. These preferences are understood within the framework of sexual selection (first proposed by Charles Darwin in 1871) and more contemporary theories that draw on evolutionary explanations, cultural variation, and evidence from actual mating behaviors. These theories account for the variation in desires for certain traits, the divergence of preference between men and women, and the adoption of short-term vs long-term mating strategies. Together, these approaches explain the origins, adaptive functions, and real-word outcomes of human mate preferences.
Influences on human mating preference A study of 37 cultures showed that, generally, culture plays a substantial role in forming human mating preference, accounting for 14% of variance across the study, with sex also having an effect on preference, although a smaller one (2.4%) than culture.
The study by Buss et al. indicated the largest difference between cultures affecting mating preference was modern versus traditional attitudes towards mating. It also indicated that sex has an effect on a few mate preferences - for example, appearance and "resource potential" - but little effect on most others.
Sexual selection One of the earliest theories posited to explain mate preferences was Darwin's theory of sexual selection. This theory came about when he noticed that certain characteristics (most famously, the feathers of a male peacock) appeared to have no survival value. Unsatisfied with his theory of natural selection as the primary driver of evolution, he proposed that sexual selection was at play. Namely, Darwin suggested two mechanisms of this evolutionary process.
The first mechanism, intrasexual selection, describes the competition with same-sex others for access to mates. This can include directly antagonistic interactions, such as physical contests and fights, or indirect interactions like competition for territory or high status positions. As a result of success in such competitions, the victors are able to mate, meaning that their heritable traits are passed down to offspring with greater frequency. Those who lost do not gain access to mates and have less reproductive success. Over many generations, this differential reproductive success causes the qualities that contribute to winning these competitions (like upper body strength, formidability, or intelligence, for example) to become more common in the population. This pattern shapes preferences because individuals who choose mates with successful, competitive traits have a greater chance of producing children who survive and are reproductively successful themselves. As a result, preferences for such advantageous traits are passed down along with the traits themselves.
The second mechanism, intersexual selection (also called epigamic selection), represents one sex's propensity to prefer and, in turn, select specific members of the opposite sex that embody preferred characteristics. Because desired qualities (like physical attractiveness or intelligence, for instance) are notably heritable, individuals who select mates who display such qualities are more likely to have children who also possess them. Over time, this process increases the frequency of preferred traits in the population and also strengthens the preferences themselves (offspring inherit both the desired traits and the preference for them). Thus, this preferential mate choice directly influences one's reproductive success.
Both processes work together to select for qualities that enhance an individual's reproductive success, favoring characteristics that improve mating opportunities (even if those characteristics do not directly improve survival) and, importantly, shaping what we deem to be preferable in a mate. These mechanisms have been substantiated across virtually every species that reproduces sexually, highlighting sexual selection theory as a pervasive evolutionary force.
Parental investment Research on human mating strategies is guided by the theory of sexual selection, and in particular, Robert Trivers' concept of parental investment. Trivers defined parental investment as "any investment by the parent in an individual offspring that increases the offspring's chance of surviving (and hence reproductive success) at the cost of the parent's ability to invest in other offspring." The support given to each offspring typically differs between the father and mother. Trivers posited that it is the differential parental investment between males and females that drives the process of sexual selection. In turn, sexual selection leads to the evolution of sexual dimorphism in mate choice, competitive ability, and courtship displays (see secondary sex characteristics). Females have a higher minimal investment in offspring than males. Minimum parental investment is the least required care for successful reproduction. In humans, females have a higher minimum parental investment. They have to invest in internal fertilization, placentation, and gestation, followed by childbirth and lactation. While human males can invest heavily in their offspring as well, their minimum parental investment is still lower than that of females.
This same concept can be looked at from an economic perspective regarding the costs of engaging in sexual relations. Females incur the higher costs, as they carry the possibility of becoming pregnant among other costs.Buss, D.M., & Schmitt, D.P. (1993). "Sexual strategies theory: an evolutionary perspective on human mating". Psychological Review, 100(2), 204. Conversely, males have comparatively minimal costs of having a sexual encounter. Therefore, evolutionary psychologists have predicted a number of sex differences in human mating psychologies.
Sex ratio Human mating is dependent on the operational sex ratio. The local operational sex ratio has been shown to have an impact on mating strategies. This is defined as the ratio of marriage-age males to marriage-age females, with a high ratio representing more males and a low ratio representing more females in the local area. When there is an imbalance of sexes, the rare sex typically has more choice, while the plentiful sex has to compete more strategically for the rare sex. This leads to the plentiful sex competing on specific areas that the rare sex finds attractive. Additionally, the plentiful sex will adopt more of the rare sex's mating strategy. In a population with a low sex ratio, females will adopt a more short-term mating strategy and will compete more intensely on things like physical attractiveness. On the other hand, in a society with a high sex ratio, males will adopt a more long-term strategy to attractive females. (See going steady.) For example, in the major metropolitan areas of China, females are generally in short supply and as such are more likely to be fulfilled should they find a mate while many men are simply left out of the dating market. On the other hand, on the Island of Manhattan and in some Western university campuses, females are in excess and as such they compete intensely for male attention, giving rise to hookup culture and short-term mating websites such as Tinder.
In 2005, the evolutionary psychologist David Schmitt conducted a multinational survey of sexual attitudes and behaviors involving 48 countries called the International Sexual Description Project (ISSR).Schmitt, D.P. (2005). "Sociosexuality from Argentina to Zimbabwe: A 48-nation study of sex, culture, and strategies of human mating" . Behavioral and Brain Sciences, 28(2), 247–274. Schmitt assessed relationships between several societal-level variables and average scores on the Sociosexual Orientation Inventory questionnaire. One variable that was shown to significantly predict a nation's average SOI score was the Operational Sex Ratio (OSR). This prediction was confirmed; OSR was significantly positively correlated with national SOI scores. Another variable that Schmitt predicted would influence SOI scores was the need for biparental care. In societies where extensive care from both parents is needed to ensure offspring survival, the costs of having sex with an uncommitted partner are much higher. Schmitt found significant negative correlations between several indices of need for biparental care (e.g. infant mortality, child malnutrition, and low birth-weight infants) and national SOI scores.
Parasite stress on mate choice The parasite-stress theory, otherwise known as pathogen stress, states that parasites or diseases put stress on the life development of an organism, leading to a change in the appearance of their sexually attractive traits. The initial research on the Hamilton–Zuk hypothesis (see indicator traits) showed that, within one species (brightly colored birds), there was greater sexual selection for males that had brighter plumage (feathers). In addition, Hamilton and Zuk showed that, comparing across multiple species, there is greater selection for physical attributes in species under greater parasitic stress. This has influenced research regarding human mate choice.
In societies with a high prevalence of parasites or pathogens, members would derive greater evolutionary advantage from selecting for physical attractiveness/good looks in mate choice compared to that derived by members of societies with lower prevalence. Humans could use physical attractiveness to determine resistance to parasites and diseases, which are believed to lower their sufferers' ability to portray attractive traits from then on and limit the number of high-quality pathogen-resistant mates. In cultures where parasitic infection is especially high, members could use cues available to them to determine the physical health status of the potential mate. Regardless of the wealth or ideology, the females in areas that are more at risk or have higher rates of parasites and diseases would weigh masculinity more highly when rating potential mates. Scarification: In pre-industrial societies, body markings such as tattoos or scarifications are predicted to have been a way in which individuals could attract potential mates, by indicating the reproductive quality of a person. Meaning, scars on the body could be viewed by prospective mates as evidence that a person has overcome parasites and is thus more attractive to potential mates. Research investigating this hypothesis (Singh and Bronstad 1997) found that in instances of increased pathogen prevalence, the only anatomical area with evidence of scarification in females was found on the stomach, with no evidence found for male scarification. Masculinity: In societies where there are high levels of parasites or diseases, the females, as the overall health of members decreases, are predicted to increasingly emphasize masculinity in their mate preferences. Women look for signs of masculinity in areas such as the voice, face and body shape of males. The face, in particular, may hold several cues for parasitic resistance and has been the subject of most attractiveness research. Polygamy: Tropical areas were originally associated with polygynous societies as a result of the surrounding environment being both ecologically richer and homogeneous. However, whilst tropical areas were associated with polygamy, pathogen stress is predicted as a better indicator of polygamy and has been positively correlated with it. Furthermore, over the course of human evolution, areas which had high levels of parasite-stress may have shifted the polygamy threshold and increased the presence of certain types of polygamy in a society.
Criticisms