What we are able to bring to the mating market—be it in relation to physical appearance, personality or resources—can also have a profound effect on what we consider to be, and not to be, physically attractive.

Specifically, individuals are more likely to be attracted to, and end up in, a relationship with others who are similar to them in terms of physical, social and psychological traits.

This effect is strongest for social and demographic traits (such as age, political orientation and religious attitudes), moderate for psychological characteristics like general intelligence and physical attributes, and weakest for personality characteristics.

Indeed, assortative mating appears to be the norm for human beings, with spouses tending to be similar to each other on a range of traits, including physical traits such as overall attractiveness, height and facial attractiveness. Moreover, physical features are typically positively correlated within couples, and married partners typically tend to resemble each other to the extent that their faces can be correctly matched by strangers.

Some studies suggest that there are fitness benefits as a result of assortative mating, and theoretical studies have highlighted the possibility that assortative mating may be highly adaptive. Assortative mating may maximize outbreeding while optimizing inbreeding, which has a stabilizing effect on genetic variance. That is, assortative mating such that ‘like prefers like’ facilitates reproduction between genetically similar mates, which favors the stabilization of genes supporting social behavior, with no kin relationship between them.

Certainly, studies have shown that assortative mating affects the genetic structure of populations, influencing the evolutionary dynamics of sexual organisms, which would suggest that it should have an important influence on psychological behaviors.

Moreover, it has been suggested that imprinting—memorizing in early development the visual image of parents and then using these images of mate choice—may guide assortative mating in humans. Children tend to resemble their parents and there is some evidence of mechanisms that allow humans to ‘imprint’ the faces of their parents at an early age. The visual memory created by this imprinting process may then be used to select a mate, producing assortative mating as a consequence.

While assortative mating can be interpreted as evidence of active mate choice, Barrett et al. (2002) have argued that it could also be interpreted as a best-of-a-bad-job strategy. That is, having failed to entice better mates, we seek alternative strategies of mate choice which eventually lead to relationships with people who are similar to us. One such strategy is to lower one’s standards, which widens the range of potential mates. For example, in a study of American personal advertisements, Waynforth and Dunbar (1995) found that men who lacked resources were more willing to accept a woman’s children from a previous marriage compared to men who did offer resources. These authors suggest that this represents a trade-off: men who recognize that they have little to offer in the way of resources attempt to make up for this by seeking alternatives that they hope will make them appear more attractive to the opposite sex.

A similar study by Cashdan (1993) asked participants to rate their agreement with a series of statements about mate attraction tactics. This study found that women who did not expect much parental investment from a potential mate were more likely to flaunt their sexuality in order to get pre-reproductive resources from men. By contrast, women who expected parental care from prospective mates were more likely to agree with statements extolling chastity and fidelity.

Men too showed a corresponding tendency: those who were unlikely to invest favoured flaunting their sexuality to women, while those who were likely to invest emphasized chastity and fidelity.

RELATED RESEARCH: Fewer Options, Better Mate Choice

Pawloski and Dunbar (1999) have also considered how an individual’s market value affects her or his willingness to make demands of a preferred partner. Based on British population data, they calculated that the best man was a combination of his income and probability that he would still be married to a woman 20 years later. On the basis of these calculations, Pawloski and Dunbar (1999) then examined whether individuals were sensitive to their standing in the mating market in terms of how demanding they were of potential mates (quantified as the number of traits they believed a partner should possess).

In general, they found that there was a significant correlation between market value and how demanding both women and men were, suggesting that we adjust our demands based on self-evaluations of our standing in the mating market.