Mate choice in humans

Physical attractiveness and symmetry

Physical attractiveness is highly desired among men and women because it functions as a cue to fertility and health. Moreover, a very attractive mate would likely produce offspring that are also attractive, enhancing their fitness.^[4][5][6][7] Though men tend to prioritize and prefer physical attractiveness more so than women, it is still a quality that is highly desired by both sexes.^[8][9]

Symmetry is one of the many aspects that factors into attractiveness for both men and women.^[10] Both facial and bodily symmetry are considered to be very attractive because they essentially act as a certificate of good health and reproductive potential (developmental stability, genetic diversity, and parasite resistance, for example).^[11][12][13] Fluctuating asymmetry, or deviation from perfect bilateral evenness, can indicate poor genetic quality and is thus deemed undesirable in a mate.^[14] Preference for symmetry in a mate is observed cross-culturally, indicating its robustness as a cue to good health.^[15]

Research shows that physically attractive individuals have better sex lives.^[16] Symmetry in particular is a good predictor of the number of sex partners one has.^[17] Furthermore, more symmetrical men tend to have their first intercourse at an earlier age than do less symmetrical men.^[17]

Good health

A healthy appearance is very desirable in a mate because it can indicate a resilient body that is free from chronic illness/disease with a low exposure to pathogens.^[18] Health is an important mate preference, as poor health can be passed onto offspring or to a partner and consequently decrease fitness.^[2] Because aspects of health are genetically influenced, it is imperative that one chooses a healthy mate in order to increase the fitness of progeny, both directly and indirectly.^[2][19]

Visible indicators of health include bilateral symmetry, skin condition, and sexual dimorphism.^{[20][10][21][22][23]} For example, clear skin tone and complexion is broadly considered to be desirable in a mate, functioning as a signal of health and high quality genetics.^[24] The presence of sexually dimorphic traits also indicates health, as both estrogen and testosterone (hormones that produce sexually dimorphic traits) are known immunosuppressants.^[21][22] Because these hormones temporarily reduce immune function, only individuals with robust underlying health can afford to produce and maintain strongly sex-typical traits. Thus, a person with sexually dimorphic traits (like a small chin in females or a large jaw in males) signals good health– only those with high genetic quality would be able to develop such masculine or feminine qualities.^{[21][22][25][26][23]}

Odor preferences

In humans, there is evidence that women will rate men's odor as more pleasant if the odor has MHC-dissimilar antigens, which is proposed as a way of avoiding inbreeding and increasing heterozygosity.^[27][28] However, women on contraceptive pills rate the odor of MHC-similar men as being more pleasant, it is unknown why women on contraceptive pills rate smell in this way. It was found that when processing MHC-similar smells were processed faster.^[29] Contrary to these findings, other studies have found that there is no correlation between attraction and odor by testing males' odor preferences on women's odors. The study concludes that there is no correlation in attraction between men and women of dissimilar HLA proteins.^[30] Research completed on a Southern Brazilian student population resulted in similar findings that found significant differences in the attraction ratings of giving to male sweat and MHC-difference.^[31]

Facial preferences

Human facial preferences have been shown to correlate with both MHC-similarity and MHC-heterozygosity.^[32] Research into MHC-similarity with regards to facial attractiveness is limited. One study found that women may prefer mates with MHC-similar faces, despite evidence that they prefer men with dissimilar body odors.^[27] While facial asymmetry hasn't been correlated with MHC-heterozygosity, the perceived healthiness of skin appears to be.^[33] It appears to be that only MHC-heterozygosity and no other genetic markers are correlated with facial attractiveness in males^[34] and it has been shown that so far that there is no correlation that has been found in females.^[35][36] Slightly different from facial attractiveness, facial masculinity is not shown to correlate with MHC heterogeneity (a common measure of immunocompetence).^[37]

Criticisms

A review article published in June 2018 concluded that there is no correlation between HLA and mate choice.^[38] In addition to assessing previous studies on HLA-Mate choice analysis to identify errors in their research methods (such as small population sizes), the study collects a larger set of data and re-runs the analysis of the previous studies. By using the larger data set to conduct analysis on 30 couples of European descent, they generate findings contrary to previous studies that identified significant divergence in the mate choice with accordance to HLA genotyping. Additional studies have been conducted simultaneously on African and European populations that only show correlation of MHC divergence in European but not African populations.^[39]

Kindness and empathy

Kindness, the quality of being nice or friendly, is consistently ranked as one of the top priorities in a mate.^{[42][9][41][8]} Displays of kindness and empathy may indicate a tendency to cooperate with others and place a partner's needs relatively high in processes of decision-making. In addition, kindness can signal greater parenting ability.^[43]

Intelligence

Intelligence is also consistently ranked by men and women as a top priority for a mate.^[42][9][41] Greater cognitive ability can help partners figure out the complex challenges that may arise when making decisions, managing a household, raising children, and solving everyday problems.^{[citation needed]}

Dependability

Dependability is preferred by men and women because it communicates a partner's likelihood of maintaining commitment throughout the relationship as well as remaining steady and reliable during difficult times.^[42][9][41]

Social status

Many people prefer a mate who maintains a high social status within their community.^[44][45][46] A mate who is highly respected by others in their social network would be able to gain access to resources and, in turn, confer upon their family.^[44][45][46]

Love

Love, the deep emotional bond that underpins long-term romantic relationships, is consistently valued across cultures.^[47] It is a human universal^[48] and has been suggested to act as a commitment device designed to promote stable pair bonding, cooperation in parenting, and reproductive success.^[49][50][51]

Honesty

A mate's honesty is highly valued and preferred by both men and women.^[42][9][41] Honesty, or the tendency to tell the truth, is a trait that can signal loyalty in many important domains. Honest behavior can reflect the general propensity to act transparently instead of manipulating or exploiting others.^{[citation needed]}

Humor

Humor, the quality of being funny or entertaining, is widely desired among men and women.^[8] Research suggests that humor functions as an honest signal of cognitive capacity, creativity, and social intelligence– qualities that reflect fitness.^[52][8]

Relationship satisfaction

One prominent theory as to why these preferences are rated as very desirable and important for many people is their association with relationship satisfaction. This theory posits that some qualities (such as kindness or empathy) greatly contribute happiness within the relationship.^[42] Unkind or unempathetic partners may decrease relationship satisfaction and, as a result, increase the likelihood of relationship dissolution. Other trivial qualities (such as good housekeeping skills) are deemed less important in a relationship simply because they don't have a significant effect on relationship satisfaction or maintenance.^[42]

Evolutionary biology

Another theory as to why some qualities are consistently desired among men and women is the traits' association with reproductive investment capability.^[42] Essentially, this theory states that mate qualities like physical attractiveness or intelligence are considered important and desirable because they are more greatly correlated with parental investment abilities than are traits like good housekeeping skills.^[42] As a result, minor traits (such as good housekeeping skills) are not widely desired or prioritized. Ancestral humans who prioritized mate preferences that served proximate cues to reproductive investment capabilities were able to have more offspring and thus propagate their genes with a greater frequency.^[42]

Both of these theories are not incompatible. They likely, in fact, work together to strengthen the importance of certain mate preferences from two different angles.

Function

Women may prefer to acquire a short term mate in some scenarios. There are 4 possible adaptive functions to preference for short-term mating strategies.^[60]

One explanation is that she may need to acquire immediate resources, and mating with a man (with the ability to confer benefits) would secure those resources (for her and her children).

Secondly, she may wish to participate in short-term mating in order to acquire good genes for her future child. This is known as the Good Genes Hypothesis.^[3] Some lines of evidence suggest that women prefer short-term mates when target mates have indicators of high genetic quality, such as facial symmetry, masculine features, and high physical attractiveness.^{[61][62][63][64][65][66]} This is partly explained by the fact that short-term mating is a profitable mating tactic for highly masculine men, and research has found correlations between high levels of masculinity and low levels of romantic/parental investment.^[67][68] Since men who have such cues of high genetic quality may be more inclined to engage in short-term mating, women who want to secure good genes for her offspring must also engage in short-term mating.^[69]

Another explanation is that she may be evaluating a short term mate for a possible long-term relationship.

Lastly, she might engage in short term mating during acts of infidelity. In this case, a short-term mating strategy functions as a means to mate switch, an outcome that may occur following an extrapair copulation. Four variants of mate switching have been identified.^[3]

• First, a woman may engage in short-term mating in order to acquire a backup mate, acting as a sort of mate insurance if something were to happen to her primary mate.
• Next, she may use short-term mating as a means to facilitate disinvestment in an existing mate.
• Thirdly, a woman could engage in short-term mating in order to acquire a mate who offers greater benefits and fewer costs than her current mate.
• Lastly, a woman may mate in the short-term as a means to evaluate her own mate value and determine whether or not more desirable mates exist in the mating market.

Women's mate choices will also be constrained by the context in which they are making them, resulting in conditional mate choices.^[55] Some of the conditions that may influence female mate choice include the woman's own perceived attractiveness, the woman's personal resources, mate copying and parasite stress.^[59]

David Buss outlines several hypotheses as to the function of women's short-term mate choices:

• Resource hypothesis: Women may engage in short-term mating in order to gain resources that they may not be able to gain from a long-term partner, or that a long-term partner may not be able to provide consistently. These resources may be food, protection for the woman and her children from aggressive men who may capture or sexually coerce them, or status, by providing the woman with a higher social standing. Women may also benefit from having several short-term mating arrangements through paternity confusion—if the paternity of her offspring is not certain, she may be able to accrue resources from several men as a result of this uncertainty.^[59]
• Genetic benefit hypothesis: Women may choose to engage in short-term mating arrangements in order to aid conception if her long-term partner is infertile, to gain superior genes to those of her long-term partner, or to acquire different genes to those of her partner and increase the genetic diversity of her offspring. This relates to what is known as the sexy son hypothesis; if a woman acquires genes from a high quality male, her offspring will likely have higher mate value, resulting in their increased reproductive success.^[59]
• Mate expulsion and mate switching: Women may engage in a short-term mating arrangement in order to cause an end to a long-term relationship; in other words, to facilitate a break-up. Women may also use short-term mating if their current partner has depreciated in value, and they wish to 'trade up' and find a partner that they believe has higher value.^[59]
• Short-term for long-term goals: Women may use short-term sexual relationships in order to assess a mate's value as a long-term partner, or in the hopes that the short-term arrangement will result in one that is long-term.^[59]

Masculine physical attractiveness

For women, short-term mating (i.e., engagement in low-commitment sexual acts, such as a one-night stand) could be extremely costly due to obligatory parental investment (e.g., gestation, lactation).^[53][54] Because of this, women who engage in short-term mating are motivated to pursue men who have high genetic quality.^[70][26] One indicator of high genetic quality is physical attractiveness and the presence of sexually dimorphic features.^[25] In short-term mating, women have exhibited stronger preferences for male physical attractiveness, such as facial symmetry and masculine features (e.g., large jaw, prominent eyebrows).^[70][26]

These sexually dimorphic features are highly desired because they function as an honest immunocompetence handicap signal.^[70][26] Masculinity acts as cue to testosterone exposure, which signals high genetic quality due to testosterone's immunosuppressant effects.^[25] Because testosterone suppresses the immune system, only men with good immune systems would be able to develop these masculine secondary sex characteristics.^[70][26] Therefore, women are attracted to such dimorphic features because they indicate high quality genes that would be passed onto offspring.^[70][26]

It is proposed that this preference for sexually dimorphic features is stronger in short-term mating strategies because the male's high genetic quality is traded off for parental investment. Some evidence backs this up, as researchers have found links between high levels of masculinity and low levels of investment.^[67] For instance, high testosterone men are less likely to get married, and when they do, they tend to have more marital problems and higher rates of divorce than low testosterone men.^[67]

Local pathogen threat

Local pathogen threat is a significant influence in female preference for a masculine partner.^[71][72] Because the presence of masculine features in men is indicative of a good immune system, exposure to pathogen cues is shown to be associated with stronger preferences for male facial masculinity among women.^[69] Across a variety of cultures, it has been found that pathogen load is positively correlated with importance of partner physical attractiveness.^[71] This is further supported by data that reports females more strongly prefer masculinity in places with poorer health statuses, such as high mortality and disease rates.^[72] It has also been found that women with high sensitivity to pathogen disgust exhibit stronger preferences for masculinity.^[72]

Indeed, it has been found that men who are more masculine tend to have a higher number of sexual partners.^[73] Research shows that men with broad shoulders relative to hips (a highly sexually dimorphic quality correlated with testosterone) tend to lose their virginity at a younger age, have more sex mates, have more affairs, and have more sex with other people's mates as compared to men with lower shoulder-to-hip ratios.^[74]

Resources and financial prospects

A man's reproductive investment is highly tied to his ability to attain and confer benefits for the family.^[75] Because women pay the enormous cost of pregnancy and child rearing, ancestral women needed to solve the problem of provisioning enough food for herself and her children. Given this, ancestral women would have placed extreme importance on a mate's ability to forage, hunt, and provide meat (i.e., give benefits to her and her offspring).^[76] Today, this translates to a man's ability to bring in economic resources and provide for the family monetarily. Monetary privilege allows access to resources that may provide material and social advantages to offspring.^[75][42] Indeed, many lines of evidence from various cultures suggest that women prefer men who possess economic resources and good financial prospects.^{[77][78][79][80][76][41]}

Multiple studies have shown that this preference occurs in real mating behavior: women are more likely to select mates who have greater ability to confer economic benefits. For example, speed dating studies have shown that women are more inclined to select mates who grew up in an affluent neighborhood and had higher levels of both education and income.^[81] Another study found that women in Kenya preferentially select mates who have lots of land.^[82] Indeed, married men consistently have higher levels of income than single men of the same age.^[2] In addition, one cross-cultural study found that inadequate economic support was a frequent cause of divorce as reported by females.^[83] Divorce due to a lack of economic support never occurred among males.^[83]

The provision of economic resources, or the potential to acquire many economic resources, is the most obvious cue towards the ability of a man to provide resources, and women in the United States have been shown experimentally to rate the importance of their partner's financial status more highly than men.^[59]

Emotional stability

If a woman's long-term partner is not emotionally stable or is not dependable then their provision of resources to her and her offspring are likely to be inconsistent. Additionally, the costs associated with an emotionally unstable partner such as jealousy and manipulation may outweigh the benefits associated with the resources they are able to provide.^[59]

Love

Romantic love is the mechanism through which long-term mate choice occurs in human females.^[84]

Ambition, industry, and social status

In line with female preference for a mate's economic resources and financial prospects, women cross-culturally have shown preference for a mate's ambition, industriousness, and social status.^[77][85] For example, one study found that women rated high-status men as significantly more attractive than lower-status men.^[86] These qualities would have, again, signaled the ability of a mate to provide for a woman and her offspring.

There is lots of evidence that this preference translates into real life mating behavior. For instance, mail-order brides from a variety of countries were more likely to select men who had higher levels of status and ambition.^[87] Another study found that women were more likely to seek out mates who owned a car and placed importance on their career.^[88]

Protection

Because ancestral women were more susceptible to dangerous others, they evolved preferences for mates that signal both the ability and willingness to protect. Qualities such as dominance, a larger body size, physical formidability, athleticism, and bravery are all highly valued among women.^[3] For example, women have shown strong preferences for males who are muscular and lean with a broad chest and V-shaped torso (broad shoulders relative to hips).^[74] Many lines of evidence show that women strongly prefer tall men over short men because they are seen as more dominant and physically formidable.^{[89][90][91][92]}

Tall men are more likely to date, get responses on dating ads, and acquire highly attractive partners.^[92][91] Also, men with a high shoulder-to-hip ratio are shown to have more sex partners.^[74] Moreover, men who are perceived as dominant copulate earlier in life than their counterparts.^[93]

Age

Cross-culturally, women have shown a strong preference for men who are older than themselves.^[41][42][94] One prominent reason for this is that older men typically have greater economic security and social status than younger men.^[94] Research has shown that women actually prefer a larger age gap than do men, with an average ideal preference of 3.42 years older.^[40] Older males have had more time to accrue resources.^[59]

Multiple studies have shown that age preferences are actualized in real-world relationships. For example, many women report having a partner older than themselves.^[40][94] Consistently across cultures and centuries, women date and marry men who are a few years older than themselves.^[94][41][95]

Costs

The primary cost of employing a long-term mating strategy among women is having to forgo short-term mating opportunities and the previously described benefits they might bring.^[3]

Benefits

There are many benefits of using a long-term mating strategy for women. Namely, a woman's long-term mate can secure status and resources for herself and her offspring.^[3] Also, having a long-term mate can ensure the physical protection of herself and her family.^[3] Lastly, employing a long-term mating strategy can ensure enhanced mating success of the offspring by means of the material and social benefits acquired from a father.^[3]

Physical attractiveness

When finding a short-term mate, males highly value women with sexual experience and physical attractiveness.^[96] Men who are interested in a short-term sexual relationship are more likely to prioritise information about the body of potential partners, rather than their faces.^[96] When finding a female for a short-term relationship, compared with a long-term relationship, males are less likely to prioritise factors such as commitment.

Variety

Men have evolved stronger preferences for sexual variety than women, mostly due to the fact that parental investment is not nearly as costly for men.^[60] Men, then, should be highly motivated to acquire as many mates as possible – the only constraint to his reproductive success is the number of fertile mates he has access to.^[53][54] As a result, studies show that men, moreso than women, express a strong desire for short-term mates and want a greater number of sexual partners.^[60] Indeed, men in many countries maintain more permissive attitudes towards causal sex than do women.^[97] In comparison to women, men prefer to have sex sooner and are more willing to loosen their preference standards while seeking casual sex.^[60]

A preference for sexual variety is actualized in men's real mating behavior in several ways. For example, men tend to feel less sexual regret than women – they are less likely to be upset following a causal hookup.^{[98][99][100]} In addition, men are more likely than women to feel regret regarding missed sexual opportunities.^[101] Substantially more men than women will agree to have sex with a stranger, a finding that has been replicated across many countries.^{[102][103][104]} Cross-culturally, men solicit prostitutes far more than women do, with 99% of sex worker patrons being male.^[3] Moreover, men often report that their ideal outcome of a short-term mating experience is more sex, while women describe their ideal outcome to be a romantic relationship.^[3] On top of this, men have been shown to employ tactics of deception in order to obtain short-term sex, such as faking interest in a long-term romantic relationship.^{[105][106][3]} Furthermore, married men are more likely than married women to have affairs and with a greater number of partners.^[2] Findings in support of men's engagement in acts involving increased sexual variety have been replicated cross-culturally.^{[107][108][109]}

Men seeking short-term sexual relationships are likely to avoid women who are interested in commitment or require investment. In short-term sexual relationships, men are less choosy because of low parental investment. When looking for short-term sexual relationships, men may wish for there to be as little time as possible between each partner.^[96]

Lower standards

It has been reported that men are more likely to engage in a sexual relationship with women who have lower levels of intelligence, independence, honesty, generosity, athleticism, responsibility and cooperativeness, when this relationship is short-term.^[96] Men may be more accepting of lower standards, than what they usually prefer, because they are not entering a long-term relationship with this person.

Sexual experience

Many men assume that women who have engaged in sexual experiences beforehand are likely to have a higher sex drive than women who haven't.^[96] These women may also be more accessible and require less courtship.

Exploitability

Men who employ a short-term mating strategy are more attracted to women who possess indicators of sexual exploitability.^[110] Appearing to be immature, under the influence, flirtatious, sleepy, and wearing revealing clothing are preferred by men seeking casual sex because they are believed to be cues that a woman can be easily seduced.^[110][3] Men who desire a short-term mate are substantially more attracted to these qualities than men seeking a long-term mate.^[111] In fact, these sexual exploitability indicators are not preferred (and are found to be unattractive) by men employing a long-term mating strategy.^[111]

Reproductive value

Ancestral men who had successfully pursued a fertile mate passed down their genes with a higher frequency. As a result, men evolved preferences for cues that historically correlated with a woman's reproductive value.^[3] Reproductive value is not directly observable in women due to concealed ovulation, so it must be inferred through visible qualities.^[112] In fact, physical appearance contains lots of information about a person, like their age and health status.^[18] Most men today are attracted to women who signal high reproductive value, inferred through her age and physically healthy/attractive appearance.^{[75][113][60][114]}

Attractiveness

Indicators of relative youth and health are substantial predictors of female attractiveness judgments by men.^{[75][115][116][3]} Indeed, men reliably report preferences for a long-term mate who is beautiful and neotonous.^{[75][115][116][3]}

Physical qualities considered attractive by men include traditionally feminine and youthful features, such as full lips, facial adiposity, small chin, thin jaws, high cheekbones, clear/supple skin, facial symmetry, and clear/large eyes.^{[75][113][60][114][74]} These feminine facial features are believed to be associated with high estrogen levels, a hormone that is linked to fertility and tends to decline with age.^[117]

Other physical qualities preferred by men are healthy hair, lively gait, bodily symmetry, and firm/symmetrical breasts.^{[75][113][60][114][74][118]}

One prominent mate preference among men is a low waist-to-hip ratio (hourglass figure).^{[75][113][60][114][74]} A low waist-to-hip ratio is highly important as it is one of the best visible cues to fecundity.^[4][119] In fact, it has been found that congenitally blind men show preference for a low waist-to-hip ratio in a mate, indicating that the hourglass figure is a robust indicator of reproductive value.^[120]

Observable characteristics of a woman can indicate good health and the ability to reproduce, qualities which are likely to be desired by a male. This may include smooth skin, absence of lesions, muscle tone, long hair and high energy levels.^[121] Women with darker features (lips, eyes, eyebrows) relative to their facial skin have been found to be more attractive, as this increases facial contrast (the same features appear to decrease male attractiveness).^[122][123]

A Waist-to-hip ratio of 0.7 is an indicator of fertility, lower long-term health risks and suggests that the woman isn't already pregnant.^[121] A male is likely to desire these qualities in a mate, as it will increase the chance of survival of any offspring the couple have together.

The pigmentation of nipples and breasts appears to be the most important quality of breast attractiveness. Men rated women with dark nipples and dark areola as significantly more attractive than those with light-colored nipples or areola.^[124] Breasts of medium cup size were found to be the most attractive, however authors noted that men focused primarily on the coloration of nipples and areola rather than breast size.^[124]

Youth

Numerous studies point to the fact that men prefer a mate who is younger than themselves.^{[40][125][94]} The ideal age for a mate according to one sample of men is approximately 2.66 years younger.^[40]

Many lines of evidence support the notion that men acquire mates who are physically attractive and youthful. Typically, men who are of high status are able to actualize their preferences and, in turn, secure the most attractive mates. Across different centuries and cultures, it has been found that men with high-income, high status jobs (kings, CEOs, famous actors and musicians, etc.) often acquire spouses and mistresses who are substantially younger and more physically attractive than the average woman.^{[126][127][128][129][125][94][130]}

In addition, cross-cultural marriage statistics throughout time show that women are typically younger than their partners by anywhere from 3 to 10 years.^{[40][94][95][125]} This age gap increases as men get older– the age of their mate becomes increasingly younger.^[131] Furthermore, data from foreign bride purchases showed that men tended to select considerably younger mates for marriage.^[132]

Other behavioral data also points to a preference fulfillment for younger mates among men. For example, in cultures that take part in bridewealth practices, the age of a potential wife impacts the amount of money spent, with younger wives getting higher amounts of money.^[82] It has also been shown that men tend to spend more money on engagement rings for younger brides.^[133] Research also indicates that mate guarding tactics are more strongly employed for younger women.^[134]

Both young and old men are attracted to women in their twenties.^[135][136] Faces that appear younger are usually rated as more attractive by males.^[121]

Fidelity

Sexual fidelity, or the propensity to remain sexually devoted to one's partner, is highly valued by men and regularly placed among their top priorities in a mate.^{[60][137][138]} Such loyalty indicates a woman's commitment to the relationship, reducing the likelihood of partner defection.^[3] Remaining sexually faithful is very desirable for men because it protects against the substantial fitness costs associated with betrayal, such as cuckoldry, thereby increasing paternity certainty.^[75]

Commitment

Humans have the ability to rely on biological signals of reproductive success and non-biological signals, such as the female's willingness to marry.^[121] Unlike many animals, humans are not able to consciously display physical changes to their body when they are ready to mate, so they have to rely on other forms of communication before engaging in a consensual relationship. Romantic love is the mechanism through which long-term mate choice occurs in human males.^[84] For long-term sexual relationships, men are usually equally choosy because they have a similar parental investment like the women, as they heavily invest in the offspring in form of resource provisioning.

A human male may be interested in mating with a female who seeks marriage.^[121] This is because he has exclusive sexual access to the female, so any offspring produced in the relationship will be genetically related to him (unless the female has sexual intercourse with another male outside of the marriage). This increases the likelihood of paternity certainty. With two married parents investing in the offspring, their chance of survival may increase; therefore the male's DNA will be passed on to the children of his offspring. Also, a male who is interested in committing to a female may be more attractive to potential mates. A male who can promise resources and future parental investment is likely to be more appealing to women than a male who is unwilling to commit to her.

• Facial symmetry: Symmetrical faces have been judged to signal good general health and the ability for a woman to withstand adverse environmental factors, such as illness.^[121]
• Femininity: A feminine face can be a signal of youth, which in turn signals strong reproductive value.^[121] As a woman gets older, her facial features become less feminine due to ageing. Femininity can also be linked to disease-resistance and high estrogen levels, which are factors that suggest reproductive value to a potential mate.

Costs

In line with the costs for women, a long-term mating strategy for men may be costly because he must relinquish other short-term sexual opportunities.^[3]

Benefits

There are many benefits to pursuing a long-term mating strategy for men. One benefit is that he may utilize a woman's lifetime reproductive means.^[3] In doing so, a man may gain paternity certainty.^[3][139] Furthermore, he may enhance the fitness of his offspring via parental investment and strengthen social power via his alliances with his partner's family.^{[140][60][139]} Given the fact that many women require commitment prior to engaging in a sexual relationship, a man may benefit from employing a long-term mating strategy by simply increasing the chance of attaining a mate at all.^[60][139]

Necessities

One study showed that, when given a small budget, people prioritize mate traits that were ancestrally significant for reproductive success.^[8] These traits are thought to be necessities, meaning they are considered essential in a mate.

Luxuries

When given a large budget, participants allotted resources to traits considered luxuries – qualities that are desirable but nonessential in a partner.^[8]