Sexual jealousy

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https://en.wikipedia.org/wiki/Sexual_jealousy

Two are Company, Three Are None, 1872, a wood engraving by Winslow Homer

Sexual jealousy is a special form of jealousy in sexual relationships, based on suspected or imminent sexual infidelity. The concept is studied in the field of evolutionary psychology.

Basis

Evolutionary psychologists have suggested that there is a gender difference in sexual jealousy, driven by men and women's different reproductive biology. The theory proposes that a man perceives a threat to his relationship's future because he could be fooled into raising children that are not his own. In contrast, a woman risks losing to another the relationship and all the benefits that entails. Research has shown that men are impacted more by sexual infidelity, while women are more impacted by emotional infidelity.

An alternative explanation is from a social-cognitive perspective. Typically, men place importance on their masculinity and sexual dominance. When the male's partner commits sexual infidelity, these two components of his ego become severely threatened. Women are more emotionally invested in a relationship, and therefore experience a threat to their self-perception when a partner commits infidelity, more concerned with risk to the emotional content than the sexual.

Some research has suggested that there are no gender differences in sexual jealousy, concluding that males and females both equally experience distress over emotional and sexual infidelity. Sexual jealousy is cross-culturally universal but how it manifests itself may differ across cultures.

Gender-specific behaviors

Female

Are You Jealous? by Paul Gauguin. Based on a real-life episode during Gauguin's stay on Tahiti, the painting shows two Tahitian women.

Psychologists have found that males react very strongly to sexual infidelity, whereas females are more likely to forgive a one-time sexual adventure if it does not threaten the male parental investment. Therefore, jealousy is likely to be evoked in females if they feel that their partner may leave them for another woman; this has been shown to be more likely to occur if the male commits emotional infidelity. Emotional infidelity occurs when one partner develops a meaningful, emotional attachment with someone outside of their primary romantic relationship.

Emotional jealousy

Many studies have shown that females tend to place a stronger emphasis on the emotional aspect of infidelity over the sexual aspect; it is this emotional infidelity that becomes the focus of female sexual jealousy. The most direct evidence for female's focus on emotional jealousy comes from Buss et al. (1992) who presented participants with scenarios in which they were asked to choose between a partner's sexual unfaithfulness and a partner's emotional unfaithfulness as the most distressing event. They found that more females than males reported a partner's emotional infidelity as the most distressing event. As well as using self-report measures, the researchers measured the participants' physiological responses (heart rate and electrodermal activity) to the scenarios; women were also found to be more physiologically upset to the idea of their partners committing emotional infidelity.

Male

See also: Uxoricide

Male sexual jealousy functions to defend paternity confidence, and is likely to have evolved through natural selection to prevent cuckoldry — a threat to males since they risk expending resources to support the biological offspring of others. The male reaction stereotypically manifests as the emotion of jealousy, using or threatening violence to protect sexual exclusivity, and thus the inclination to control women. This idea of males ensuring sexual exclusivity has also led to laws on adultery.

From an evolutionary perspective, sexual jealousy arises from this threat of investing in non-biologically related offspring and thus is most strongly felt over their mate's sexual infidelity than their emotional infidelity. It can take several forms in behaviour: aggression and violence, and possessiveness or controlling behaviour towards their mate. In some cases, sexual jealousy can lead to uxoricide. Threats to a relationship can arise from other sources too, such as the presence of rivals, cues to infidelity, and partner dissatisfaction with the relationship. Morbid jealousy is also concurrent with male sexual jealousy – an obsession with thoughts of a partner's suspected sexual infidelity. A 2012 meta-analysis found that sexual jealousy in males can also lead to emotions such as distress, hurt and disgust being experienced.

Expression

Expression in females

Aggression

While most empirical research suggests that males are more likely to act aggressively in response to sexual jealousy, some studies have shown that females may also display aggression and violence.

Women have been found to report that their hypothetical sexual jealousy would manifest itself as anger and physical aggression towards the man. It has been suggested that this is because women are more empathetic towards the "victim", triggering strong aggression towards the unfaithful man. However, it is not known if these hypothetical reports would become actions in real life situations. Furthermore, statistics on domestic violence continue to show that in relationships it is primarily men who are the abusers, rather than the women.

Because it is the woman who ultimately chooses the mate, aggression caused by infidelity may be directed at the rival female. As a result, when a woman is around a suspected rival female, she may be more likely than a male counterpart to announce that her companion is "taken" and go out of her way to enhance her appearance to her spouse.

Self-blame

Following infidelity, women are more likely to focus their sexual jealousy on their own relationship and self-blame. They are also more likely to experience symptoms of depression following the infidelity. Evidence for the interpretation that in jealousy situations women focus more on their own functioning as a partner comes from research by Dijkstra and Buunk (2002). This research suggests that unlike men's jealousy, women's jealousy stems more from comparing their own qualities with those of the rival. The higher the level of social comparison, a personality characteristic referring to the tendency to compare one's characteristics with those of others, the more jealousy various rival characteristics evoked.

Expression in males

Mate guarding behaviour

Main article: Mate guarding in humans

One form of male sexual jealousy is mate guarding. This tactic is used to prevent partner infidelity and thus may be used when there are perceived threats in the environment. It results in several behaviours, and researchers have documented up to 19 different tactics used. This includes (but is not exclusive to):

• Violence (or at least hostility) directed towards competitors,
• Taking up all of the mate's time so that they have no time to meet other potential mates,
• Emotionally manipulating their mate,
• Increase their possession signals with jewelry, clothing, cars, etc.,
• Enhancing their appearance (e.g. fixing their hair, clothing, etc.).

Attachment style

According to attachment theory, the quality of a child's interactions with caregivers during times of need shape their future interactions; this includes later relationships. Research has shown that insecure-avoidant individuals tend to report more sexual jealousy than those who are securely attached. This may be due to the fact that, in comparison to securely attached individuals, those who are insecurely attached tend to experience lower levels of trust, intimacy and stability in their romantic relationships. Evidence suggests that people who experience low self-esteem are much more afraid that their partner is dissatisfied and being unfaithful, which again increases the likelihood that they will experience sexual jealousy.

Sex drive

Sex drive, also known as libido, is the physiological need for sexual activity. Sex drive has been found to be a significant predictor of higher sexual jealousy in both men and women; those who had a higher sex drive showed greater distress at the idea of their partner committing sexual infidelity. This is consistent with other empirical research that has shown that individuals who value sexual gratification highly were more likely to be distressed by sexual infidelity. To explain this finding, researchers have suggested the key threat that sexual infidelity poses for individuals with a high sex drive is loss of access to sexual gratification, as their partner is granting sexual access to a third person.

Relationship quality

Research has shown that individuals who reported high jealousy scores had more stable and successful relationships than individuals who reported comparatively low jealousy scores. Furthermore, individuals in committed relationships tend to experience higher levels of jealousy than individuals in less committed relationships. To explain this, researchers have proposed that those in better quality, more committed relationships would have more to lose if their partner were to leave them for someone else, and therefore worry more about infidelity. Therefore, such individuals experience greater sexual jealousy if they feel the relationship is threatened.

Explanations

Researchers have proposed a number of theories to explain sexual jealousy in both males and females. In addition, some of these explanations can be used to explain the sex differences in sexual jealousy and why there may be differences in the degree to which people experience jealousy.

Evolutionary psychology perspective

Evolutionary psychologists propose that the core function of sexual jealousy is to retain access to a valuable mate. This explanation is known as jealousy as a specific innate module, "JSIM". According to this perspective, sexual jealousy should be activated by threats to the relationship; in particular, threats of sexual infidelity by the female and threats that the male may share his resources (money, protection, or time) with another woman. For males, their biggest concern when they commit to a relationship is ensuring that any offspring produced is biologically theirs, therefore, sexual infidelity is a huge threat to them as there is then a chance that they are not the genetic parent. If a male raises a child that is not genetically his own, he has effectively wasted his resources raising another man's child who will not pass on any of his genes.

As women have genetic certainty when they bear a child, this is not a concern to them. However, they do face a different evolutionary problem. If the woman's partner becomes emotionally attached to another woman, there is a real chance that the male may share his resources with the other woman or leave their current relationship altogether. Either way, the female loses some of the male parental investment, and the loss of her mate's resources may significantly reduce the survival of herself and her offspring.

The evolutionary psychology perspective has been supported by a study conducted by David Buss. He observed that male sexual jealousy is triggered by sexual infidelity, whereas female sexual jealousy is triggered by emotional infidelity. The study concluded that sexual jealousy may be an adaptive function that is triggered in order to retain access to a valuable mate.

Researchers David Buss and Todd Shackleford propose and test several hypotheses about sexual jealousy:

1. Men will devote more resources to mate retention when their partner is younger than them than men whose partner is older than them. This hypothesis rests on the evolutionary principle of mate value. Younger women are likely to have more mate value because they are more fertile. Therefore, it is predicted that men are likely to engage in mate retention behaviours more often when their partner is younger rather than older than them.
2. Again based on the principle of mate value is the prediction that men will devote more resources to mate retention when their partner is perceived to be more physically attractive than when their partner is perceived to be less physically attractive. Females who are physically attractive have a higher mate value than those who are less physically attractive.
3. Women will allocate more resources to mate retention when their partner has a wealth of resources than women whose partners have few resources. This hypothesis also rests on the mate value principle. Men who have more resources and wealth have a higher mate value than those who do not.
4. If a man perceives his partner as having a higher mate value than him, then he is more likely to engage in efforts towards mate retention than men who perceive their partners as having a lower or equal mate value than them. This hypothesis rests on perceived mate value. If a male's partner has a higher mate value than him, she is more likely to be able to attract other men who may be of a similar mate value to her. As such, the male is at a greater risk of losing her to another man with a higher mate value.
5. Individuals who suspect their partners are being unfaithful are more likely to devote effort towards mate retention than those who do not suspect their partners are being unfaithful. This hypothesis relies on the perceived probability of infidelity. Men risk being cuckolded into raising children that are not genetically theirs, and women risk losing their mate's resources and time.

Their research provided evidence to support all above hypotheses except for hypothesis 5; this effect was unique to men only. This suggests that a woman who suspects her male partner of being unfaithful is not necessarily more likely to devote more effort to retaining them:

One could speculate that a partner's sexual infidelity signals less of a loss for women than for men given the reproductive logic of paternity uncertainty, but this explanation does not square with the findings that women become just as upset as men by a partner's infidelity, particularly when it represents a serious, emotionally involved relationship (Buss et al., 1992).

The double-shot hypothesis

This hypothesis contradicts the evolutionary perspective. It proposes that these gender differences in feelings of sexual jealousy stem from beliefs as opposed to being evolved traits.

The double-shot hypothesis (also known as the two-for-one hypothesis) suggests that women have a belief that men can have sexual relations without emotionally committing themselves. Women also believe that for men to have emotional commitment, sex is a prerequisite. Therefore, if men and women place importance on different aspects of relationship, this explains why they may also be upset by different types of sexual jealousy differently.

Social-cognitive perspective

As both forms of jealousy are threatening to men and women, the social-cognitive perspective suggests that there are no inherent, evolutionarily induced gender differences. Instead, both emotional and sexual jealousy are believed to occur when an individual believes that a rival is posing a threat to what one perceives to be a valuable interpersonal relationship. When the relationship or one's self-esteem is threatened, jealousy is evoked.

The perspective also provides explanations as to why men would be more upset by sexual infidelity than women. Men are socialized to be masculine, which includes having great sexual prowess. If a man's partner commits sexual infidelity, this brings into question his sexual prowess and therefore threatens his masculinity. This results a strong, negative reaction in response to the sexual infidelity, which does not tend to occur in response to emotional infidelity. In contrast, women are taught to be emotional nurturers in a relationship, therefore, if their partner commits emotional infidelity, this may threaten her sense of self more than if her partner commits sexual infidelity.

The social-cognitive perspective also proposes the transactional model of jealousy, which can be used to explain why there may be differences in the degree to which individuals experience sexual jealousy within genders, as well as between genders. This model examines how three variables – (1) arousability, (2) commitment and, (3) insecurity – moderate jealousy.

1. Individual differences in sexual jealousy are determined by the difference in levels of physiological arousal: individuals who are easily aroused have more intense jealous reactions than those with lower physiological arousal
2. Commitment refers to the degree of dedication a person has in the relationship: the more committed a person is to a relationship, the greater the threat of loss, which leads to greater feelings of jealousy
3. Insecurity refers to the perceived level of commitment of the partner: if we perceive our partner to be un-involved or disinterested in the relationship, we feel more insecure.

The degree to which these factors are experienced together determine the intensity of sexual jealousy felt by an individual.

Culture

Sexual jealousy is cross-culturally universal in industrialised countries and affects both men and women. However, the extent of sexual jealousy varies across cultures. Sexual jealousy is strongly mediated by culture in both heterosexual and homosexual couples. It is said to be prevalent in males who are from patriarchal cultures (where heritability runs through the male side).

Evocation

There are cross-cultural differences in behaviours that evoke sexual jealousy. Specifically, one study focused on seven different countries: Hungary, Ireland, Mexico, the Netherlands, the Soviet Union, the United States, and Yugoslavia. Different behaviours were found to elicit different extents of sexual jealousy. For instance, flirting, kissing and sexual involvement elicit sexual jealousy across all these nations. However, dancing, hugging and kissing evoke very different reactions across cultures. In the Soviet Union, the most sexual jealousy is seen across dancing, hugging, flirting and kissing behaviours. Yugoslavian participants display the most intense sexual jealousy to flirting behaviour but the least to kissing. Dutch participants show the least sexual jealousy to kissing, dancing and hugging behaviours.

In Western cultures

Societies that permit extra-marital sexual relations often discourage sexual jealousy. For example, in Denmark very low sexual jealousy rates are determined by the very low 10% disapproval of extra-marital sex. On the other hand, individuals in the American Midwest show high feelings of sexual jealousy which corresponds to the 90% disapproval of extra-marital sex.

American men also feel more sexual jealousy compared to German men when asked which would cause them more distress: i) a partner having formed a strong emotional attachment with another person or ii) a partner having passionate sexual intercourse with another person. Scenario i) measured emotional jealousy and scenario ii) measured sexual jealousy. The American men reported 33% greater sexual and emotional jealousy compared to German men.

Greater sexual jealousy seen in American men may be because in American culture, love, sex, family relationships and marriage are strongly connected. So when partners entangle with others, loss of love and relationship and therefore sexual jealousy, are all likely to be felt.

Additionally, in Western culture, women are more likely than men to trigger sexual jealousy. Inducing sexual jealousy is to increase their partner's attention towards them and counteract sexual and emotional jealousy.

However, Western culture now is mainly monogamous which is very different from the environments in which the majority of evolution thus far has occurred. Therefore, evolutionarily it is likely that different past cultures also showed differences in sexual jealousy.

In Asian or Eastern cultures

Cross-cultural comparisons between China and United States reveal that, regardless of nation, men show greater sexual jealousy than women. Females show significantly higher levels of emotional jealousy. In contrast, between the nations, both men and women from the United States show greater sexual jealousy than Chinese individuals.

In contemporary India, sexual jealousy is a primary cause of violence towards women compared to other causes. In an Indian sample, approximately fifty-one per cent of the violence towards women was due to sexual jealousy.

In history, between 1880 and 1925, there was a large number of suicides amongst Indian immigrants on plantations in Fiji that reports attributed to sexual jealousy. Sexual jealousy was high amongst these immigrants due to the disproportionate ratio of sexes: a high number of men to a low number of women. In suicide reports, sexual jealousy was described as a "racial trait" belonging to Indian men and was evoked when European men slept with Indian women during an era of European colonization of India.

Explanations for cross-cultural differences

Evolutionary psychology model

The differences in feelings of jealousy across cultures support the evolutionary psychological model. Different weights are given to triggers of sexual jealousy depending on the culture. In liberal cultures, male mating effort is based on the number of women the male has copulated with. These men therefore invest less time in each woman and thus exhibit less sexual jealousy.

Paternity certainty

Paternity certainty is the extent to which a man knows or believes that a woman's child is his.

In polygamous societies, men feel greater sexual jealousy when there is low paternity certainty. This is because they do not want to risk wasting time, energy and resources on a child that is not theirs.

Socio-economic differences between cultures also affect paternity certainty. In a natural fertility country such as Namibia, 96% of males show sexual jealousy.

Additionally, there is greater likelihood of paternity loss and paternity uncertainty when there is a lack of contraceptives. This provides an explanation for why industrialised countries tend to show lower sexual jealousy compared to pre-industrialised countries.

Mate guarding in humans

From Wikipedia, the free encyclopedia
https://en.wikipedia.org/wiki/Mate_guarding_in_humans

Female mate guarding in humans

Human mate guarding refers to behaviours employed by both males and females with the aim of maintaining reproductive opportunities and sexual access to a mate. It involves discouraging the current mate from abandoning the relationship whilst also warding off intrasexual (same sex) rivals. It has been observed in many non-human animals (see mate guarding and sperm competition), as well as humans. Sexual jealousy is a prime example of mate guarding behaviour. Both males and females use different strategies to retain a mate and there is evidence that suggests resistance to mate guarding also exists.

Male

Circumstances of use

Male mate guarding is the act of guarding a potential partner from other competing males. Mate guarding behaviour in males is much more likely to be elicited by the threat of sexual infidelity in a female partner, in comparison to emotional involvement outside the mateship. According to a 2004 study across multiple countries, 62% of men have attempted to mate poach for a short-term relationship, as opposed to 40% of women. “In most world regions, women report less frequent poaching attempts for short-term and long-term relationships than men. (Hudek-Knezevic et al., 2022) Schmitt et al. (2004) report that, across countries, an estimated 62% of men and 40% of women have attempted to mate poach for a short-term relationship.” (Fisher M., Wade J., and Moran J., 2023). For long-term poaching, the difference was smaller, but still existent nonetheless, with 60% of men and 53% of women having attempted to mate poach for a long-term relationship. “The sex difference was smaller for long-term mate poaching, but still present—60% of the men and 53% of the women.” (Schmitt & Buss, 2001). These results are similar to those found in a prior 2001 study among college-aged individuals, where 64% of college-aged men were found to mate poach, as opposed to 49% of college-aged women. Mate poaching attempts among older adults constituted 60% of men and 38% of women. “Schmitt and Buss (2001) found college-aged men (64%) are more likely than college-aged women (49%) to have attempted poaching a short-term mate. These rates are higher than those observed in older adults (60% of men, 38% of women).” (Fisher M., Wade J., and Moran J., 2023). “The first scientific study of mate poaching (Schmitt & Buss, 2001) found that substantially more men (60%) than women (38%) admitted to having attempted to poach an already mated person for a sexual encounter.” (Tierney J., 2009). Another study sampling participants across ten different countries showed that 57% of men and 35% of women have attempted to mate poach. “Across ten world regions, 57% of men and 35% of women indicated they had engaged in an attempt at mate poaching.” (Hanson R., 2009). This especially raises concern primarily due to the risk female infidelity poses for male paternity, or 'genetic cuckoldry'. In other words, as fertilisation takes place within females, males do not have paternal certainty in the way that females do (females can always be certain that the offspring is theirs, whilst a male cannot). There is supporting evidence for this cross-culturally in a varied range of countries such as China, Germany, Japan and Sweden. Moreover, in physiological tests such as skin conductance and heart rate, men show greater levels of distress when asked to imagine a partner having sexual intercourse with another person. It is also worth noting that mate guarding tactics are more likely to be used if the partner is of high reproductive value e.g. if the female displays signs of high fertility such as youth and physical attractiveness.

Risks

If a male does not successfully prevent a rival's attempt at mating, there are many risks. If the female becomes fertilised, then the male loses the opportunity to reproduce with that partner for an extended period of time and his genes will not be passed on to the offspring. Moreover, the male may invest years of time, resources and energy into a child that is not genetically his own. If this becomes public knowledge, the individual may also face public humiliation, and as a result this could reduce his social status and affect his future chances to reproduce. There are also 'opportunity costs'; wherein the male could have been spending lost time pursuing alternative mating options.

Male mate guarding behaviour also needs to ensure that the female does not leave the mateship as this would reduce future chances the male may have to reproduce. Moreover, the male would also lose any maternal efforts the female would have invested in any potential offspring. Additionally, access to any social benefits or helping networks that the female brought to the relationship could be lost. Finally, the female could also use information, such as strengths or weakness, about the male to exploit him in the future.

Strategies

Mate guarding tactics employed by males tend to be hiding the female from intrasexual threats; this could be not bringing the mate to social events in which other competing males may be present. Another is to request that the female wear items that indicate possession, this could be a wedding ring or the male's jacket for example. Males may also demonstrate the quality of resources they have to offer (e.g. buying the mate gifts, or paying for a meal). Men are also more likely to employ threatening and violent behaviour towards intrasexual rivals.

Female

Female mate guarding is the act of guarding a potential partner away from other competing females. It occurs when women mate with males that are seen as desirable due to their paternal value (see mate value), and are therefore more likely to attract other females. Despite women being 44% less likely than men to mate poaching, one study showed that over 50% of females asked in a survey admitted to poaching for long-term relationships (see Human mate poaching), as well as 50% of men admitting that they were unfaithful when presented with a poaching female. It is therefore a balancing act between having close female friendships that can help with childcare, and the sharing of resources, but not letting friends become too close that they have easy access to poach successfully. Females have therefore come up with tactics to ward off any potential threats.

Avoidance

Female mate guarding concentrates on avoiding attractive, fertile females.^[7] Research suggests that females are more likely to avoid women that are attractive and exclude them from the group, as these women are interpreted as potential poachers.^[11]

Ovulating women are also seen as a threat. Research has shown that women subconsciously change their behaviour across their menstrual cycle, such as dressing more provocatively, which is noticed by men. In one study, men rated photos of ovulating (fertile) women as more attractive, compared to photos of women who were in the luteal (infertile) stage of the menstrual cycle. It is suggested that men are therefore more likely to pursue ovulating women, which become potential threats to their female mates.

Krems, Neel, Neuberg, Puts and Kenrick (2016) also found that women created larger social distance between themselves and a competing female, but only if she was ovulating and attractive. Similarly, this only occurred if the woman was partnered with a desirable mate. This is suggested to be because other females, especially those who are ovulating, are less likely to desire men that have limited resources.

Proximity

Across the world, it is common for people to sleep in the same bed as one another after copulation. Humans are more likely to engage in sexual activity at night, so therefore night-time brings the highest danger of infidelity. Due to females investing more in the relationship, women receive more benefits from sleeping with their mate during the night. Keeping close proximity with a partner acts as a mate guarding technique as it minimises the likelihood of unfaithfulness by the male, and also assures their partner of her fidelity. As a result of the paternal confidence, the male is also more likely to stay and provide resources. In one study it was found that 73.7% of participants said that females are more likely to want to sleep together after sexual intercourse. Mate guarding is a very likely explanation to this, but it may also have the benefits of increasing the female's protection, potentially from male poachers.

Failure to introduce

One way to overcome this issue is to avoid introducing threatening friends (potential mates of higher value) to desirable mates. In one study women were shown three pictures of the same female. In one picture the model was dressed conservatively, in the other two she was dressed provocatively, but in the third the model had been photoshopped to have a larger frame. All the women tested rated the thin, provocatively dressed women as the sexiest. Participants were also twice as likely to avoid introducing the model to their partners compared to the conservatively dressed model, who was rated as the least threatening. The authors interpreted these findings as, women who are dressed provocatively are seen as more promiscuous, so therefore are less likely to be introduced to partners due to the possibility of poaching. Not introducing an attractive female to a mate, minimises the likelihood that poaching will occur as it is a form of indirect aggression that minimises contact between a mate and a potential threat.

Resistance

Responses to mate guarding, specifically female resistance to it, have also been observed in both humans and other animals. Responses to mate guarding by males has not been extensively studied. Resistance to mate guarding has been suggested to provide some benefits to partners who do so. In animals, particularly crustaceans, it is argued that resistance allows females to reduce the amount of time the male guards her, giving her more control over mating, as the benefits of mate guarding by males are not worth the costs of trying to overcome resistance from the female. It is therefore suggested that resistance to mate guarding in animals could be a mate choice strategy for female animals. Seeing as mate guarding serves to reduce mate choice, resistance may allow females to ensure they have access to resources from one mate and also look for higher genetic quality extra pair mates to ensure her children are more likely to survive and reproduce themselves. This is known as the female dual mating strategy theory and relates to sexual selection.

Tactics

Research suggests that female animals exhibit resistance to mate guarding behaviours. There have also been a few studies focusing on mate guarding resistance in female humans. There are numerous tactics that have been recognised as female mate guarding resistance strategies. These include:

• Covert tactics - e.g. hiding items from the partner or flirting/speaking to other men when the initial partner is not present
• Resistance to public displays of affection - e.g. not letting the partner act affectionately towards you in front of others i.e. holding hands or cuddling
• Reactions against rival - e.g. defending rival males when their partner confronted them for expressing an interest in the female
• High tech covert tactics - e.g. changing passwords or deleting online or virtual conversations with rivals over text or email
• Avoiding partners contact - e.g. ignoring calls or texts from the partner
• Resisting control - e.g. fighting about how controlling their partner is or wanting more independence in the relationship

Across the menstrual cycle

Female resistance to mate guarding has also been researched in the context of the menstrual cycle. Pillsworth, Haselton and Buss (2004) found that women are more likely to want to mate with males they are not currently pair bonded with during the ovulation period of their menstrual cycle. They also show higher mate guarding resistance in general during oestrus. This is supported by the finding that during ovulation women who are both single or in a monogamous partnership with a man are more likely to desire to go to social gatherings where they may meet alternative mates. This is said to support the female dual mating strategy theory, as during oestrus women may be seeking out mates with strong genes.

Partner qualities

Different qualities of the male partner have also been found to affect the existence of resistance to mate guarding in females. Research has found women with partners who have a low genetic quality, as defined by low sexual attractiveness in comparison to available resources, are more likely to show mate guarding resistant behaviours. This is supported as recent research by Abell and Brewer (2016) suggests that women who believe alternative mates compared to her pair bonded male are of a higher quality are also more likely to resist mate guarding too.

Women married to more possessive, controlling or jealous husbands are more likely to be unfaithful as well. Women who experience this type of behaviour from their partners are more likely to show mate guarding resistance particularly by using covert tactics.

Individual differences

There is also research into individual differences in female resistance to mate guarding. A recent study by Abell and Brewer (2016) has focused on Machiavellianism. They found that women high in this trait are more likely to resist mate guarding attempts and use covert tactics to do so. They suggest that this reflects the characteristics of machiavellianism – using glibness and manipulation to get what is wanted and it is argued that this is their way of controlling their partners. This is supported by the finding that females who are more controlling themselves will use more mate guarding resistant tactics too.

Women who have a more unrestricted sociosexual orientation index may also be more likely to resist mate guarding too. This type of sociosexuality is defined by more promiscuity and low levels of intimacy in relationships. Related to this, females who report less investment in their current relationship also exhibit more resistance to mate guarding by avoiding contact with their partner. This strategy along with resisting control has also been found to be more widely used for women who report less intimacy in their relationship.

There has been some research looking into attachment style and mate guarding resistance too. It has been found that women who show more avoidant attachment styles are more likely to resist their partners mate guarding attempts. They are most likely to use avoiding public displays of affection, covert tactics and resisting a partners control as resistance strategies. Those who express anxious attachment styles are more likely to resist mate guarding via covert methods.

Parasite-stress theory

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Parasite-stress_theory 

Schistosoma mansoni, an endoparasite that lives in human tissue

Parasite-stress theory, or pathogen-stress theory, is a theory of human evolution proposing that parasites and diseases encountered by a species shape the development of species' values and qualities, proposed by researchers Corey Fincher and Randy Thornhill.

The differences in how parasites and diseases stress people's development is what leads to differences in their biological mate value and mate preferences, as well as differences across culture. Parasites causing diseases pose potential ecological hazards and, subsequently, selection pressures can alter psychological and social behaviours of humans, as well as have an influence on their immune systems.

Theories of parasite-mediated mate choice

Several hypotheses have attempted to explain how parasite load influences female mate choice, as certain traits are thought to be costly and the expression of such traits may be indicative of genetic quality.

Hamilton–Zuk hypothesis

An example of a cost the peacock must bear from having such a large tail. The tail requires a lot of energy as it weighs the peacock down during its flight.

According to the Hamilton–Zuk hypothesis, female mate choice is based on the extent to which male secondary sexual characteristics are expressed, as these are thought to be indicative of a heritable resistance to pathogens. A meta-analysis reviewed studies exploring the magnitude of the relationship between expression of secondary sexual characteristics and parasite intensity, as well as level of host immune functioning. Consistent with the hypothesis proposed by Hamilton and Zuk, the meta-analysis revealed that males with the fewest parasites and/or the strongest immune systems typically had the most extravagant secondary sexual characteristics. With regards to parasite-stress theory, these findings would be interpreted as those men who have encountered more parasites – or are naturally less capable of dealing with parasites – are also less desirable mates to females, due to a lower genetic quality for the potential offspring.

Zahavi handicap principle

The Zahavi handicap principle, originally proposed by Zahavi in 1975, suggests that males who possess secondary sexual characteristics which provide a handicap are more attractive to females. These sexual ornaments are sexually selected in order to appear stronger and better adapted, compared to other males in the environment. This is because these characteristics are indicators of good genes and heritable viability, as they are costly to an individual's survival to maintain and produce. Therefore, the stronger the individual is, the more able they are to bear this cost.

These kinds of characteristics are a form of communication within species, as they are defined as honest signals (a signal about a mate's quality which cannot be faked). As a weak individual would not be able to survive with this particular characteristic, it signals to potential mates that it is stronger than its competitors and has a high mate value. Examples of such traits include the peacock's tail, very bright in nature and hence attracting more attention from predators as well as requiring more energy to maintain. Another example is the gazelle's stotting behaviour, whereby the gazelle jumps up and down when it spots a predator, in order to indicate its physical fitness.

A gazelle stotting to indicate its fitness and ability to outrun a predator

Immunocompetence handicap hypothesis

This hypothesis takes Zahavi's principle further in suggesting that testosterone is responsible for the production of male secondary sexual traits while also suppressing the immune system. It therefore proposes that these traits are honest signals of mate quality because only males with 'good genes' should be able to fully express them without being vulnerable to parasite attack. Males will, therefore, demonstrate their high genetic quality by developing more attractive honest signals in substitute for their immune system's strength. These honest signals require testosterone, which simultaneously suppresses the immune system.

A meta-analysis revealed that evidence for a direct effect of testosterone on the expression of sexual traits and the suppression of immunocompetence was weak. It was found, however, that increased testosterone influenced parasite loads, indicating an indirect role of the hormone in immune function.

Parasite-mediated domestication

According to the parasite-mediated domestication hypothesis, proposed by Skok in 2023, parasites (specifically endoparasites: helminths and protozoa) could play an important mediating role in the process of domestication, with a 'parasite effect' primarily involved in the emergence of the domesticated state (proto-domestication). The hypothesis states that parasites indirectly influence literally all of the main processes that otherwise underlie the domestication syndrome (abnormalities in the functioning of the neuro-neuroendocrine system, a developmental disruption of neural crest cell input to the affected phenotypic traits, etc.). The hypothesis predicts that the frequency of domestication syndrome traits such as tameness, depigmentation and mottling, floppy ears, short and curled tail, and reduced size of the adrenal glands from the wild population increases with decreasing genetic resistance to parasites and with increasing parasite load. The hypothesis further suggests that the features of the domestication syndrome may be genetically linked to genes related to resistance or tolerance to parasites, the role of miRNA in the process of epigenetic inheritance or the transgenerational inheritance of stress pathology.

Interactions with developmental instability

Developmental instability is the inability of an organism to produce its optimal phenotype, due to genetic limitations and environmental stresses (such as parasite load).

Fluctuating asymmetry

Fluctuating asymmetry is the extent to which an organism deviates from perfect body symmetry. Asymmetry, an indicator of development, is exhibited by all organisms and is thus considered by scientists to be a reliable measure of developmental instability.

Research in a Dominican village, which measured the prevalence of protozoa and worm parasites in over 300 children, found a positive correlation between gut parasites and fluctuating asymmetry. This finding is indicative of how parasites negatively impact peoples' development and act as environmental stress factors.

A barn swallow

A literature review summarising more than 100 different studies in the field found that, among other variables, immunocompetence (the ability of an organism to produce a normal immune response to an antigen) had a significant relationship with fluctuating asymmetry. In other words, individuals who had a better ability to defend themselves against threats, such as parasites, were also lower in fluctuating asymmetry.

Waist-hip ratio

Waist-hip ratio is the ratio of the circumference of the waist, to the circumference of the hips. It is calculated by dividing the waist circumference by the hip circumference.

A woman's waist-hip ratio is an indicator of her age, health and fertility, as well as being a good indicator of other people's judgements of attractiveness, with a lower waist-hip ratio being optimal. All of the above are related to mate choice: a lower waist-hip ratio indicates a younger, healthier, more fertile and more subjectively attractive women, all of which are desirable qualities in a mate.

Higher waist-hip ratio has been linked with both mobility disability and also cardiovascular disease. Also, within parasite-stress theory itself, women with higher waist-hip ratio's also had a higher incidence of toxoplasmosis, another incidence in which parasitism contributes to developmental instability.

Mate choice

Mate choosers prefer mates who are lower in developmental instability, meaning that they choose those who display lower fluctuating asymmetry.

In barn swallows, the length of the male's tail is used as a signal of mate quality: males with longer tails are preferred to those with shorter tails. Research has found that, in a population of barn swallows infested by the parasite Ornithonyssus bursa, male barn swallows with fewer mites also had longer tails.

Variations across cultures

When discussing cross-cultural differences between societies, scientists will more often than not make a distinction between individualism and collectivism. Consequently, it is important to provide an understanding for the variations exhibited between these two cultures.

Collectivist

Research has suggested that collectivism exists to defend against infectious diseases. Therefore, cultures that have a higher rate of infections will be more likely to become collectivist. This has been based on a number of observations.

Firstly, collectivists place a lot of emphasis on their in-group, caring for one another and hence protecting each other from the negative effects of contagion. This is likely due to the fact that one's immune system works to defend the body from local parasites; however, this still allows for the risk of unfamiliar infections resulting in illness as the immune system has not been able to evolve in response to these novel parasites. Hence, ensuring that those in the in-group are not affected by a novel disease will subsequently result in a reduced risk of encountering a novel parasite from an exposed person an individual remains in close proximity with.

Secondly, collectivist cultures are untrusting of those outside of their in-group, which may serve as a protective behaviour against interactions with those in groups that may harbour novel diseases. In similar vein to the explanation presented with one's protective nature of their in-group members, one's immune system is well adapted to local parasites and will be unable to effectively protect against unfamiliar pathogens. Therefore, avoidance of those outside of one's inner circle will aid in the prevention of being exposed to novel and dangerous pathogens that the immune system is unable to defend against.

Thirdly, it has been observed that collectivist groups exhibit strong negative attitudes when an individual goes against their social norms. A relevant example is deviating from the way that food is prepared, which could result in a higher possibility of exposure to new and threatening pathogens. Hence, this strong social norm, is effectively in place to prevent group members from being negligent and becoming ill with a novel parasite – which then could pass onto other members of the group.

Individualist

Individualist societies, however, are very different to collectivist through their promotion of looking out for oneself, rather than worrying about the needs of the group. This is partly due to these cultures being predominantly in geographical locations which are under a lot less danger from parasite invasions. Unlike collectivists, individualists make much less of a distinction between in-groups and out-groups. A clear distinction, that individualism shows from collectivism, comes from the active encouragement individualist cultures place upon individuals straying from the current social norms.

Criticism

Some authors have pointed out that parasite stress is a misleading term because the described phenomenon includes viruses. A virus does not fit the definition of a parasite because a parasite is defined as an organism, and a virus is not an organism. Some authors use the name pathogen-stress theory instead.

Several scientists have criticized the theory that pathogen stress can explain differences in collectivism versus individualism, suggesting that the observed correlations were spurious. Anthropologist Daniel Hruschka and human biologist Joseph Henrich have proposed an alternative explanation of the observed cultural differences. In colonial times, European colonizers established efficient social institutions in countries with low mortality. In places where mortality was high due to infectious diseases, they set up extractive systems with less settling of Europeans. The more-efficient government institutions inherited from colonial times in low mortality countries can explain the observed differences in cultural values.

Parasite influence on food preference across cultures

This difference in culture due to pathogen avoidance has also been seen in the contrast of food preferences between cultures. Research investigated the possibility that individuals will have a preference for spices in their cooking to defend against food-borne human parasites. This was tested through measuring the types and numbers of spices used in recipes across various regions across the world – it was found that temperature was a good predictor of the use of anti-pathogen spices. This finding makes sense when considering that temperature is a breeding ground for parasites.

The Evolution of Human Sexuality

From Wikipedia, the free encyclopedia
https://en.wikipedia.org/wiki/The_Evolution_of_Human_Sexuality

 

The Evolution of Human Sexuality

Cover of the first edition
Author	Donald Symons
Language	English
Subject	Human sexuality
Publisher	Oxford University Press
Publication date	1979
Publication place	United States
Media type	Print (Hardcover and Paperback)
Pages	358 (first edition)
ISBN	978-0195029079

The Evolution of Human Sexuality is a 1979 book about human sexuality by the anthropologist Donald Symons, in which the author discusses topics such as human sexual anatomy, ovulation, orgasm, homosexuality, sexual promiscuity, and rape, attempting to show how evolutionary concepts can be applied to humans. Symons argues that the female orgasm is not an adaptive trait and that women have the capacity for it only because orgasm is adaptive for men, and that differences between the sexual behavior of male and female homosexuals help to show underlying differences between male and female sexuality. In his view, homosexual men tend to be sexually promiscuous because of the tendency of men in general to desire sex with a large number of partners, a tendency that in heterosexual men is usually restrained by women's typical lack of interest in promiscuous sex. Symons also argues that rape can be explained in evolutionary terms and feminist claims that it is not sexually motivated are incorrect.

The book received several positive reviews, as well as some criticism: it was described as the most important work on human sociobiology to date, but also dismissed as an impoverished work. It has been seen as a classic work on human sexual evolution and used as a textbook, though critics have questioned Symons's explanation of the female orgasm and his suggestion that eliminating rape "might well entail a cure worse than the disease". The work influenced the biologist Randy Thornhill and the anthropologist Craig T. Palmer's A Natural History of Rape (2000). Symons's arguments about homosexuality have received both criticism and support from commentators, and he has been both accused of supporting genetic determinism and sexism, and defended against the charge.

Summary

Symons argues that women and men have different sexual natures, apparent in their typical "sexual behaviors, attitudes, and feelings", but partially concealed by moral injunctions and the compromises inherent in relations between the sexes. He attributes these differences to human evolutionary history, writing that during its hunting and gathering phase, the sexual desires and dispositions that were adaptive for men obstructed reproduction for women, while those that were adaptive for women obstructed reproduction for men. He writes that his discussion of sex differences in sexuality is not intended to affect social policy. He discusses evolutionary concepts and the difficulties involved in applying them to humans, the capacity for orgasm, the loss of human estrus, sexual selection and its components intrasexual competition and sexual choice, the desire for sexual variety, and the development of human ovulation. He argues that among all peoples, sex is typically understood to be a service that females render to males.

In the introduction, Symons argues that modern understandings of "natural selection" and "fitness" are value-free, the latter term measuring reproductive success rather than referring to human value judgments; that it is necessary to distinguish between proximate and ultimate explanations of animal behavior, the former being concerned with how animals come to develop behavior patterns, and the latter with why they develop these patterns; that while a feature of structure or behavior may benefit an animal, only features that result from natural selection should be considered functions; that the persistence of the nature–nurture controversy is partly the result of failing to distinguish between proximate and ultimate causation; that learning abilities are more often concerned with specific problems than they are the expression of general capacities; and that the secondary sex differences that exist in animals of most species are the consequences the different reproductive behaviors of males and females.

According to Symons, while orgasm in the human female has been proposed to be an adaptation resulting from selective forces, the available evidence, which shows that the female orgasm is far from being a universal result of heterosexual intercourse and that its frequency varies greatly between cultures and between individuals, does not support that conclusion. Symons suggested that the female orgasm may be possible for female mammals because it is adaptive for males. He notes that in most mammalian species the only known function of the clitoris is to generate sensation during copulation, but saw no evidence that "the female genitals of any mammalian species have been designed by natural selection for efficiency in orgasm production." He criticizes Elizabeth Sherfey's view that the female orgasm is an adaptation, writing that her arguments are not supported by ethnographic or biological evidence. Symons proposes that male human ancestors lost the ability to detect ovulation in females by smell because females gained a reproductive advantage by concealing ovulation, and that estrus ceased to exist in humans at the same time. Observing that estrous female chimpanzees are more successful than nonestrous females in obtaining meat from males, Symons suggests that when hunting became a dominant male economic activity during human evolution, the benefits to females of receiving meat may have outweighed the costs to them of constant sexual activity, leading to women making sexual overtures to men in order to obtain meat.

In his discussion of "the desire for sexual variety", Symons reviews literature on the "Coolidge effect", the "phenomenon of male rearousal by a new female". Discussing rape, Symons suggests that because males can "potentially sire offspring at almost no cost ... selection favors male attempts to copulate with fertile females whenever this potential can be realized." He criticizes the feminist Susan Brownmiller's argument in Against Our Will (1975) that rape is not sexually motivated, writing that she inadequately documents her thesis and that all of the reasons that she and other authors have given for concluding that rapists are not motivated by sexual desire are open to criticism. Symons writes that Brownmiller's claim that the function of rape is to keep all women in a state of fear has been "vigorously contested", and that it is also an example of a naïve form of functionalism, which is unacceptable since no process that might generate such "functions" has been shown to exist. Symons argues that socialization towards a "more humane sexuality" requires the inhibition of impulses that are part of human nature because they have proved adaptive over millions of years, and concluded that while under the right rearing conditions, "males could be produced who would want only the kinds of sexual interactions that women want" this "might well entail a cure worse than the disease." He considers the major contribution of feminist investigations of rape to be to document the perspective of its victims, showing, for example, that they do not want to be raped.

Symons considers two different kinds of evidence especially important in supporting his claim that there are typical differences between the sexual desires and dispositions of men and women: hormone studies and the behavior of male and female homosexuals. Because homosexuals do not have to "compromise sexually with members of the opposite sex" their sex lives "should provide dramatic insight into male sexuality and female sexuality in their undiluted states." According to Symons, fundamental differences between men and women are apparent from the fact that, while there is a substantial industry producing pornography for male homosexuals, no pornography is produced for lesbians, and that lesbians, as compared to male homosexuals, have much greater interest in forming stable and monogamous relationships and having sex with loving partners.

He argues that the similarities between heterosexual and lesbian relationships, and the differences between both and the relations of male homosexuals, show that "the sexual proclivities of homosexual males are very rarely manifested in behavior." He proposes that heterosexual men would be as promiscuous as homosexual men tend to be if most women were interested in engaging in promiscuous heterosexual sex, and that it is women's lack of interest that prevents this. He considers, but rejects, alternative explanations for the differences between male homosexual and lesbian behavior, such as the effects of socialization, finding them unsupported. He concludes that while the "existence of large numbers of exclusive homosexuals in contemporary Western societies attests to the importance of social experience in determining the objects that humans sexually desire", the fact that male homosexual behavior in some ways resembles an exaggerated version of male heterosexual behavior, and lesbian behavior in some ways resembles an exaggerated version of female heterosexual behavior, indicates that other aspects of human sexuality are not affected by social influences to the same extent.

Background and publication history

According to Symons, the ideas that he developed in The Evolution of Human Sexuality were partly inspired by a conversation he had with the ethologist Richard Dawkins in 1968. Symons, who had concluded that "men tend to want a variety of sexual partners and women tend not to because this desire always was adaptive for ancestral males and never was adaptive for ancestral females", found that Dawkins had independently reached the same conclusion. Symons presented an early draft of the book during a 1974 seminar on primate and human sexuality he co-taught with the anthropologist Donald Brown. Symons argued in the draft that there are universal human sex differences.

Brown assisted Symons in writing the book. The book was first published in hardcover by Oxford University Press in 1979. A paperback edition followed in 1981.

Reception

Mainstream media

The Evolution of Human Sexuality received a negative review from the anthropologist Clifford Geertz in The New York Review of Books. Subsequent discussions include those by the anthropologist Craig Stanford in American Scientist and the evolutionary psychologist Nigel Barber in Psychology Today.

Geertz wrote that "virtually none" of Symons's claims are based on research Symons conducted himself, and that Symons "made no direct inquiries into human sexuality", instead basing himself on anthropological reports and other material, resulting in a book that is "a pastiche more than a study". He accused Symons of supporting his views through selective use of evidence, such as an "extremely brief and fragmentary" review of the effects of hormones on human sexuality. He considered Symons's characterizations of male and female homosexuals to be on the level of national or ethnic stereotypes, and found it questionable whether Symons's observations support his claims about differences between male and female sexuality. He questioned whether Symons was correct to believe it possible to determine what natures and dispositions men and women have prior to the influence of human culture, and criticized Symons for viewing human sexuality as a biological fact with cultural implications rather than a cultural activity sustaining a biological process. He disagreed with the favorable views of The Evolution of Human Sexuality expressed by the biologists E. O. Wilson and George C. Williams, and the then president of the American Anthropological Association, calling the work impoverished. He wrote that if the book was the most important work on human sociobiology to date, this was unfortunate.

Stanford described the book as "an early think piece rather than a thorough review of actual behavior." He noted that the biologist Randy Thornhill and the anthropologist Craig T. Palmer cited The Evolution of Human Sexuality extensively in their work A Natural History of Rape (2000), but criticized them for relying on Symons as an "authority on human mating". Barber, writing in 2011, described The Evolution of Human Sexuality as the "classic rejoinder" to Brownmiller's argument that rape is not sexually motivated, and credited Symons with a "resounding defeat of Brownmiller". However, he wrote that since it was published, date rape has emerged as the most common type of sexual assault and that "College men do not fit the profile of rapists drawn by Symons because they have high social status rather than being underprivileged."

Scientific and academic journals, 1979–2000

The Evolution of Human Sexuality received positive reviews from the anthropologist Sarah Blaffer Hrdy in The Quarterly Review of Biology and the psychologists Martin Daly and Margo Wilson in The Sciences, a mixed review from Elmer S. Miller in Social Science Quarterly, and a negative review from the anthropologist Judith Shapiro in Science. Subsequent discussions include those by Lisa Sanchez in Gender Issues.

Hrdy credited Symons with being one of the first to apply evolutionary theory to human sexuality and described The Evolution of Human Sexuality as "an insightful, theoretically sophisticated, and delightfully literate examination of the sexual emotions of men and women" and "the best available study of human sexual emotions." She predicted that many social scientists, but few zoologists, would disagree with Symons's conclusion that there are innate psychological differences between men and women. She found Symons's review of biological literature on the "Coolidge effect", and the sociobiological literature on adultery, valuable, and although she found his "extrapolating from the Coolidge effect to human philandering" open to question, considered his discussion of the relationship between nature and culture more sophisticated than that of most sociobiologists. She credited Symons with usefully drawing on both traditional anthropology and sociobiology. She found his treatment of female sexuality both more original and more controversial than his treatment of male sexuality, and argued against his view that many aspects of female sexuality, such as the female orgasm, were only accidental by-products of evolution.

Daly and Wilson wrote that Symons brought an "even-handed, critical intelligence" to the discussion of the evolutionary basis of sex differences, and that he was willing to criticize the writings of sociobiologists where appropriate. However, they found Symons's discussion of the evolution of concealment of ovulation in humans less useful than that of several other authors, including Hrdy, and concluded that Symons was not fully successful in establishing criteria to determine whether a given feature of an animal is an adaptation. They observed that though "seemingly bizarre", Symons's argument that the sexual behavior of homosexuals helps to test hypotheses about sex differences in sexuality is logical.

Miller described The Evolution of Human Sexuality as well-written and fascinating, but argued that Symons, with his focus on reproductive success, did not fully answer questions about "the relevance of nonhuman animal studies for an understanding of human social life." He pointed to infanticide as an example of a phenomenon that was difficult to explain in terms of reproductive success arguments, especially since "killing is generally performed by the mother." He also argued that "the epistemological foundation of research that assigns culture the status of epiphenomena" was open to debate, and that Symons limited the value of his contributions by ignoring the "question of cultural significance".

Shapiro considered Symons's thesis about human sexuality unprovable, and argued that by outlining the relevant theoretical and methodological issues carefully and clearly he showed the difficulties to be greater than he realized. She maintained that his conclusions were only acceptable if one already agreed with sociobiology. She wrote that he attached too much importance to the idea that reproductive strategies explain relations between men and women, thereby connecting human sexuality too closely to reproduction, and accused him of showing no awareness of "the many meanings that sex can take on in different cultural settings." She criticized his views on subjects such as the motivations for rape, marriage, and the female orgasm, and also faulted the quality of his "cross-cultural data on erotic activity." She described his argument that "the innate sexual tendencies of men and women are mostly truly expressed in the behavior of homosexuals" as "ingenious". She also maintained that his work was unlikely to appeal to social scientists.

Sanchez noted that Symons's view that rape is not an adaptation has been questioned by Thornhill and Palmer. However, she considered Symons correct to caution that the available data are insufficient to support the conclusion that rape is an adaptation.

Scientific and academic journals, 2001–present

The socialist feminist Lynne Segal argued in Psychology, Evolution & Gender that Symons mistakenly believed that women, by being "continuously copulable", cause men to desire to engage in promiscuous sexual relations with them. She saw Symons's endorsement of the "genetic determinism" of the biologist Randy Thornhill and the anthropologist Craig T. Palmer's A Natural History of Rape (2000) as following from the views he expressed in The Evolution of Human Sexuality.

Palmer and Thornhill noted in the Journal of Sex Research that while Symons stated that did not "believe that available data are even close to sufficient to warrant the conclusion" that rape is a "facultative adaptation in the human male" and therefore concluded instead that rape is "a by-product of various different sexual adaptations in men and women", he failed to specify exactly how the available data were insufficient to support the conclusion that rape is a facultative adaptation or what kind of data might potentially demonstrate that rape is a facultative adaptation. They added that given Symons's failure to explain the shortcomings of the available data or explain how it could be improved upon, it was understandable that the question of whether rape is an adaptation was more thoroughly investigated by other researchers, including Thornhill himself.

Jocelyn Bosley described The Evolution of Human Sexuality as an influential work in Signs. However, she criticized Symons for accepting at face value the idea that men are "more motivated than women to seek sex." Bosley wrote that Symons argued that female orgasm is a byproduct of the existence of the male orgasm through an "infamous and widely cited" comparison of the female orgasm to male nipples. She questioned the idea that Symons's willingness to separate "female orgasm from female reproductive fitness" has feminist implications, writing that while Symons "lent scientific support to some feminists' claims for a primordial similarity between male and female sexuality", other feminists found his account of female orgasm "socially and politically regrettable". She concluded that Symons "thoroughly undercut the position of feminists who maintained that true sexual equality would be achieved only when peculiarly female sexual experiences were recognized and galvanized as the basis for a new, egalitarian sexuality."

David Puts, Khytam Dawood, and Lisa Welling argued in the Archives of Sexual Behavior that while Symons's proposal that the human female orgasm is a non-functional byproduct of orgasm in men is plausible, it is a hypothesis that "currently lacks empirical support", that there is some counter evidence, and that the issue remains unresolved.

Dean Lee argued in Biology and Philosophy that Symons's account of the female orgasm has been misinterpreted in the scholarly literature. According to Lee, while Symons's case that the female orgasm is not an adaptation attracted controversy, little attention was given to the alternative explanation of the female orgasm Symons provided. He described this alternative explanation as "obscure, complicated, and frankly speculative". He maintained that Symons did not, as has been assumed, offer the same explanation of the female orgasm as that later put forward by the evolutionary biologist Stephen Jay Gould, according to which the female orgasm is possible because of the clitoris, which is a byproduct of the embryological connection with the male penis. He identified Symons's alternative argument as being contained in the sentence in which Symons wrote that, "The female orgasm may be a byproduct of mammalian bisexual potential: orgasm may be possible for female mammals because it is adaptive for males." He interpreted Symons as maintaining that orgasm is a typically male trait based on a mechanism in the brain that exists in individuals of both sexes: a woman who experiences an orgasm during heterosexual intercourse is exhibiting bisexual behavior because her mating response to a male is female behavior and her orgasm is a male behavior. He questioned whether Symons actually intended to make an analogy between the existence of the female orgasm and that of the male nipple, writing that Symons's comments on the issue had been taken out of context.

Other evaluations, 1979–1992

Brian Easlea argued against Symons that desire for anonymous sex is actually typical only of sexist men and is not characteristic of men in general. He rejected Symons's view that socializing men to "want only the kinds of sexual interactions that women want...might well entail a cure worse than the disease". The feminist Susan Griffin considered Symons's view that the female orgasm is only a byproduct of selection for the male orgasm an example of the ideology of the "pornographic mind", which conceives of female sexuality as "an empty space which craves male presence, and which cannot exist without the male". Hrdy argued that for Symons, "women have sexual feelings for much the same reason that men have nipples: nature makes the two sexes as variations on the same basic model", a view of female sexuality she considered reminiscent of Aristotle and 19th century Victorianism.

The biologists Richard Lewontin and Steven Rose, writing with the psychologist Leon Kamin, observed that, like some other sociobiologists, Symons maintains that "the manifest trait is not itself coded by genes, but that a potential is coded and the trait only arises when the appropriate environmental cue is given." In their view, "Despite its superficial appearance of dependence on environment, this model is completely genetically determined, independent of the environment." They concluded that Symons's arguments provide examples "of how sociobiological theory can explain anything, no matter how contradictory, by a little mental gymnastics". The biologist Anne Fausto-Sterling observed that while Symons believes that rape should be eliminated, he also states that the rearing conditions needed to eliminate rape "might well entail a cure worse than the disease." She criticized his position. Daniel Rancour-Laferriere described The Evolution of Human Sexuality as an "important treatise". However, he argued that the evidence Symons cites about animal behavior actually suggests that the female orgasm is adaptive.

The sociologist Jeffrey Weeks criticized Symons's view that differences between male and female sexual attitudes have a biological basis, arguing that it was not supported by Symons's evidence. The gay rights activist Dennis Altman argued that Symons wrongly maintained that gay men, due to their nature as men, are incapable of monogamy. The philosopher Michael Ruse concluded that while Symons's explanation of male homosexual promiscuity could be correct, it depends on controversial and disputable claims. The ethologist Irenäus Eibl-Eibesfeldt questioned Symons's argument that the absence of visible female estrus developed so that women could "offer themselves to men" for rewards of food. He noted that prey is shared in chimpanzees without sexual rewards. He rejected Symons's argument that the infrequency of the female orgasm shows that it has no function. The ecologist Jared Diamond called The Evolution of Human Sexuality "outstanding". The economist Richard Posner called the work the "best single book on the sociobiology of sex". The anthropologist Helen Fisher criticized Symons's view that "homosexual behavior illustrates essential truths about male and female sexual natures". The psychologists Steven Pinker and Paul Bloom wrote that Symons's observation that "tribal chiefs are often both gifted orators and highly polygynous" helps to show "how linguistic skills could make a Darwinian difference."

Other evaluations, 1993–2004

The journalist Matt Ridley argued that Symons's ideas about the evolution of gender differences had revolutionary implications, since "the overwhelming majority of the research that social scientists had done on human sexuality was infused with the assumption that there are no mental differences" between the sexes. He endorsed Symons's explanation of male homosexual promiscuity. The psychologist David Buss called The Evolution of Human Sexuality "the most important treatise on the evolution of human sexuality in the twentieth century" and a "classic treatise".

The journalist Robert Wright called the book "the first comprehensive anthropological survey of human sexual behavior from the new Darwinian perspective". He credited Symons with showing that the tendency for men to be more interested than women in having sex with multiple sexual partners holds good across many cultures and is not restricted to western society. The philosopher Maxine Sheets-Johnstone observed that while The Evolution of Human Sexuality is "used as a textbook and is considered a major formulation of human sexuality", she sees as the work "a paradigm of the prevailing Western biological view" of female sexuality, a view she considers "essentially male". The critic Joseph Carroll described the book as a "standard work" on its subject. However, he criticized Symons's arguments about homosexuality. The sociologist Tim Megarry dismissed The Evolution of Human Sexuality as, "a projection of American dating culture onto prehistory". The anthropologist Meredith Small argued that the work of sex researchers Masters and Johnson, which shows that the female clitoris is made of the same tissue as the penis and responds sexually in a similar manner, suggests that the clitoris results from an embryonic connection with the male penis and supports Symons's view that it is not an adaptation.

Williams called The Evolution of Human Sexuality one of the classic works on "the biology of human sexual attitudes", alongside the work of Hrdy. Alan F. Dixson described Symons's explanation of male homosexual promiscuity as "interesting". The biologist Paul R. Ehrlich described The Evolution of Human Sexuality as a "classic but controversial treatise on human sexual evolution". He identified Symons's study of the development of human ovulation as a landmark. Thornhill and Palmer identified Symons as the first author to propose that rape is by-product of evolutionary adaptations. They observed that Symons has falsely been accused of basing his arguments on the assumption that behavior is genetically determined, even though he explicitly rejects that assumption and criticizes it at length. They endorsed his explanation of male homosexual promiscuity, and his arguments against the idea that rape is not sexually motivated.

Gould commented that the argument that the clitoris is not adaptive, put forward by Symons and subsequently by Gould himself, has been widely misunderstood as a denial of the adaptive value of the female orgasm in general, or even as a claim that female orgasms lack significance. The anthropologist Melvin Konner called The Evolution of Human Sexuality "the classic introduction to the evolutionary dimensions" of sex. Pinker called The Evolution of Human Sexuality "groundbreaking". He criticized what he considered personal abuse of Symons by Lewontin et al. in their discussion of the book.

Other evaluations, 2005–present

Buss called The Evolution of Human Sexuality the first "watershed in the study of human mating strategies" to follow evolutionary biologist Robert Trivers' 1972 paper "Parental Investment and Sexual Selection" and a "trenchant classic". He credited Symons with being "the first to articulate the theoretical foundations of a fully adaptationist view of male and female mating minds" and "the first social scientist to take the writings of George C. Williams ... to heart, applying rigorous standards for invoking the critical but challenging concept adaptation." He described The Evolution of Human Sexuality as "the first major treatise on evolutionary psychology proper, highlighting the centrality of psychological mechanisms as adaptations and using human sexuality as a detailed vehicle for this more general argument."

Elizabeth Lloyd concluded that Symons proposes "the best available explanation for the evolution of the female orgasm", stating that while Symons's conclusions are not beyond dispute, and have been criticized on a number of different grounds, they are consistent with existing evidence, and help to explain "otherwise mysterious findings." Thornhill and Steven W. Gangestad described The Evolution of Human Sexuality as "a landmark in the study of human sexuality" and "the first serious effort to investigate and inquire into the nature of human sexuality". They added that many of Symons's ideas have received support, including his view that women's sexuality includes "sexual adaptation that functions to gain access to nongenetic material benefits from males through its expression when women are not fertile within their menstrual cycles."

The anthropologists Anne Bolin and Patricia Whelehan identified as Symons one of two major participants in the debate over the reproductive role of the female orgasm, the other being Sherfey. They wrote that Symons's view of female sexuality "reflects western concepts of the passive female and overlooks the evidence of actual female sexual functioning, such as the capacity for multiple orgasms in women." They considered the female orgasm more likely to be "an extension of the pleasurable sensations associated with coitus in primate females generally" than a by-product of the male orgasm, as proposed by Symons. They observed that while Lloyd endorsed Symons's view, her work has been "severely criticized" by the psychologist David P. Barash, and the relationship between female orgasm and reproduction remains a topic of ongoing debate. Christopher Ryan and Cacilda Jethá called The Evolution of Human Sexuality a "classic". However, they also accused Symons of having a "bleak" vision of human sexuality. The anthropologist Peter B. Gray and Justin R. Garcia maintained that demographic data supports an evolutionary account of human mating psychology similar to that proposed by Symons.