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The Strangeness and Origins of Human Sexuality

Written By

Nikolai S. Rozov

Submitted: January 13th, 2022 Reviewed: January 14th, 2022 Published: March 8th, 2022

DOI: 10.5772/intechopen.102666

Human Sexuality Edited by Dhastagir Sultan Sheriff

From the Edited Volume

Human Sexuality [Working Title]

Dr. Dhastagir Sultan Sheriff

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This chapter focuses on critical problems of the nature and genesis of human sexuality: the classic concept of different sexual strategies of men and women, primordiality and naturalness of monogamy, the disinterestedness of women in sex, evolutionary “side effect” of female orgasm. We present and discuss inescapability of adultery, the diversity of sexual relations in pre-state societies, the revealed mechanisms of competition and selectivity in the anatomy and physiology of male and female reproductive organs. The modern versions of the adaptive significance, functions of the female orgasm deserve particular attention. Neither “egoistic” explanations (retention of a partner and “hunting” for good genes) nor esthetic ones (self-value of pleasure) are sufficient. The evolutionary hypothesis explains the genesis of emotional and sexual syncretism in women and the “cleavage” (dualism) of male sexuality. Women’s feelings toward men come from girls’ love and commitment to fathers and older men as protectors. Their feelings toward mothers remain intact: close relationships and at least partial identification with mothers remain in the majority. In boys, the original love for mothers inevitably suffers a crisis both in phylogeny through sexual selection, masculine culture, and in ontogeny through negative reinforcement.


  • sexuality
  • sexual strategies
  • evolution of sexuality
  • paleopsychology
  • female orgasm
  • “sperm war
  • ” primate sexuality
  • sex differences
  • human reproductive system
  • psychology of love

1. Introduction

It is hardly necessary to prove the enormous importance of gender relations, sexuality, and the inseparable spheres of kinship and inheritance. However, despite the enormous amount of research in this field, especially over the last 40–50 years, some questions that seem simple, even ridiculous, have not received a universally recognized answer, and researchers did not reach a consensus. Here are just a few of the questions.

  • Why does adultery, not only on the part of men but also on women, persist despite centuries of moral, religious, customary, and state law systems, despite significant risks?

  • If the female orgasm is not a by-product of the evolution of the male orgasm (as everyone has already agreed), what function does it serve? Why does it not always happen and not in all women?

  • How can we explain such an apparent difference between the usual integrity, syncretism of women’s feelings and splitting, disconnectedness of feelings in men?


2. Sexual strategies and primordial monogamy: the dubiousness of the classical model

Sexual strategies are adaptive solutions to the task of finding a match. In such terms, D. Symons [1] described and explained the difference between these strategies. A woman invests much more energy, time, and attention in carrying and raising each child, so she is interested in a long-term relationship with a man who will take care of her and the children, protect and provide resources. The man’s contribution is much more modest, so he is interested in spreading his genes as widely as possible and is prone to many short-term relationships with different women. The same concept assumes a low libido level in women, their firm attitude to monogamous marriage [ibid]. In this paradigm, a man offers food, valuable things, protection, and status in exchange for exclusive and permanent sexual access. It is considered as a fundamental “sexual contract” too [2, 3]. Researchers have assembled an extensive and impressive list of arguments that contradict the main points of this almost classical concept [4, 5].


3. The diversity of sexual orders and strange ideas of partial paternity

The monogamous marriage we are accustomed to, and the strict condemnation of adultery are by no means so widespread when we consider societies outside the most numerous nations. In many societies, extramarital sex was allowed for specific categories, such as between brothers and daughters-in-law (Siriono in eastern Bolivia).

“These people were “monogamous,” but men were permitted to have sexual intercourse with their wife’s sisters and with their brothers’ wives. Women, in turn, could have sex with their husband’s brothers and their sisters’ husbands. Among the Haida tribe, married men and women were generally permitted sexual relations with anyone belonging to the spouse’s clan; at most, the husband or wife could “object softly.” Usually, he or she did not” ([4], p. 148).

Among the most diverse cultures of the savage level (hunter-gatherer, not converted to agriculture, usually egalitarian), the belief that a pregnant woman should continue intercourse for the full development of the fetus, and preferably with different men, is rather characteristic ([6, 7]; p. 10).


4. What do the earliest signals of erotic attraction?

Let us pay attention to the following points, which usually escape from attention when analyzing such a “simple” subject as a female erotic attraction. First, women’s inviting bodily “ornaments” appeared much earlier than any clothes, probably together with the loss of body hair. It means that they were visible to everyone around them, including men, to whom they directed these signals. Secondly, girls and women usually like dances, singing, facial expressions, costumes, headdresses, jewelry, and aim them at the public. If women are not wrapped in deaf sacks and kept locked up, the propensity for all this behavioral and material adornment of the self does not disappear even after marriage, when there is no need to compete for the most attractive suitors. If women were programmed to please only one man from ancient times, their main passion would be some bodily practice like stroking or massaging their partner. It does happen, but it is nothing compared to women’s passion for adornment, dancing, and coquetry in public.

When we extrapolate all these points to groups of our most distant ancestors, we get the idea of a pretty egalitarian community with no or very little control over women’s behavior who seduce the men around them with their physical beauty and adornment grace.

Alas, women also commit adultery [8, 9]. If the ease and profitability of widespread genes in men are enough to explain their more frivolous behavior (or desires, at least), why do women have sex with new partners? Some experts think women may benefit indirectly through superior offspring born from an extramarital affair, or they may benefit directly, receiving material benefits from the lover both for themselves and their children ([4], p. 59). Let us add to this women’s need for love, for emotional commitment to a man [10].

Whom do they choose? What makes up the erotic appeal of men? A strong, beautiful male body, men’s rhetorical abilities (“women love with their ears”), as well as their confidence, dominant behavior, the visible prestige of power, wealth, fame, or intelligence (depending on the social and cultural environment), are “read” by women on a subconscious level as features of sexual attraction [11].

Men have their ways of competing for attention: these are all kinds of contests in strength, agility, the height of jumping, good luck in hunting, in games imitating chasing, hunting, or fighting with enemies. Note that all these traits are also public, and men do not lose interest in such activities and rivalries after choosing a bride and getting married.


5. The oddities of male “rigging”

The usual and seemingly natural often becomes a bundle of oddities. Many researchers interpret unusual features in the structure of human reproductive organs quite unequivocally — as anatomical traces of former fierce competition of cavaliers for fertilization. The main battlefield was not fights of individuals before copulation, but large-scale “battles” between millions of sperm of two and more cavaliers after multiple sexual intercourses with one woman [4, 12, 13, 14, 15]. Here is a list of the main arguments.

  • The size of male testicles, on the one hand, indicates the predisposition of our distant ancestors (800–200,000 years ago, kya) to frequent coitus with different females (as male chimpanzees and bonobos do), but it does not reach the size of their testicles, because the human ones decreased during the transition to polygamy and monogamy (10–5 kya).

  • The human penis, with its particular thickness and extra thickening of the head in humans, is designed to remove the preceding sperm.

  • Male “turbogenitalia”with “impressive firepower of sperm,” with abundant ejaculations, less frequent than in chimpanzees and bonobos, but more voluminous, are helpful only if designed to win such rivalry. Otherwise (for simple fertilization), they are entirely unnecessary.

  • The hazardous location of the testicles in the vulnerable outer scrotum can have only one evolutionary explanation: a chilled portion of semen must be on hand at all times, which implies a regime of frequent unplanned copulations, in all likelihood with different ladies.


6. Reproductive mechanisms as military technology: why is it so complicated?

For several decades now, the “sperm war”has been a hot topic in studying human sexuality [7, 12, 14]. Ejaculation usually takes place in several thrusts. Scientists have managed to isolate their contents and analyze them. In the beginning, it turned out that along with a portion of sperm, substances that protect against chemical attacks are injected. The thing is that for a woman’s organism, spermatozoa are alien bodies — antigens, particular leukocytes, the number of which exceeds the number of spermatozoa by 100 times or more, are directed to their destruction [13, 16].

Besides, the substances of the first ejection protect from substances from the past ejections of other men. They also have their antidote — spermacids, which slow down the movement of new alien spermatozoa. Besides the “normal” spermatozoa, which look for eggs to fertilize, there are others. These “warriors” look for and destroy foreign spermatozoa if they are present in the woman’s genital tract. Thus, the sperm’s chemical and microbiological ammunition is designed to defend itself and attack the enemy [12, 17].

In all this, the woman’s body does not remain a passive “battlefield.” During the contraction of the vagina, the semen of one man can be expelled, while the semen of the other man will be retracted. With its chemical environment, leukocytes, anatomical and physiological barriers in the vagina, cervix, and on the surface of the egg itself, the female body creates obstacles for most spermatozoa, but it helps a select few [4].

The complex structure of the cervix indicates that it has evolved to filter, temporarily storing sperm, and from different cavaliers. As a result, the egg captures not any spermatozoa but those with “suitable” characteristics [14, 15]. Therefore, females can benefit from comparing many males without intercourse with the same “high-quality”partner [18].


7. The female orgasm: atavism or valuable evolutionary gain?

A critical component of the classical concept of the “naturalness” of monogamy and women’s “low interest” in sex was the treatment of the female orgasm as an optional and not particularly necessary by-product of the male orgasm, just as nipples in men are useless, but not a hindrance either [1, 19]. This version occurred to be wrong as it has faced strong arguments against “sidedness” [4]:

  • the female orgasm is mighty and vivid, and in all aspects (muscular contractions, hormonal, and nervous, psychophysiological processes), subjectively impressive and meaningful for women;

  • the complex arrangement of this phenomenon involves a long and sophisticated evolutionary adjustment;

  • the head of the clitoris has a huge number of nerve endings (over 8000), more than anywhere else on the human body, twice as many as in the very sensitive head of the penis; and the only function of the clitoris is sexual sensation and orgasm;

  • orgasm does not occur in all women, and even those who experience it do not consistently achieve it; there is a selectivity here, an influence of circumstances, which again is in no way consistent with “collateralism.”

We will not discuss primitive and erroneous versions of the functionality of the female orgasm (luring women to have sex, facilitating fertilization through muscular contractions or horizontal posture).

The most plausible versions are those based on the idea of such an essential female concern as choosing the best partner for marriage and parenthood. It is the already classic theory of emotionally “tying down” a partner and then fathering one’s children so that in a “daddy at home” situation, they can grow up more nourished, safe, and successful [7].

The following points do not fit into this concept.

  • There is a strange dissonance between how long it takes a woman to “warm-up” and how quickly men cool down after they have achieved it.

  • Loud, often uncontrolled female cries at orgasm; such sounds (moans, loud breathing, growling) excite men no less, and often even more than the sight of a naked female body; this testifies to a well-organized “signal/reaction” pair, which has all signs of innateness, universality and, therefore, is a trace of a very ancient evolutionary adaptation.

  • Such sounds made by female primates during copulation serve to arouse and attract other males [20]; female primates practicing promiscuity make more complex, intricate sounds during copulation than females of monogamy or harem species [15, 21].

  • Males are particularly aroused by scenes that have an explicit relation to sperm competition; photos and videos of one woman and several men are much more popular on the Internet and in commercial pornography than one man’s contact with multiple women [22].

  • The complex mechanisms of female postcopulatory selectivity of semen from different men in the genital tract. It turns out that during orgasm, there is a change in acidity in the vaginal environment, which probably helps the spermatozoa of the man who brought the woman to orgasm to survive and reach their target.

  • In this respect, female vocalization during coitus gets the function (unconsciously, of course) of a potential invitation: “Come here, take part in the competition for the reproductive prize!”

Such, to put it bluntly, scandalous behavior in contemporary societies and known history occurs only in the situation of orgies — rare, closed, and, as a rule, morally reprehensible, forbidden group practices. The overwhelming number of sexual acts and orgasms do occur in situations of solitude. The involuntary sounds at the apex of orgasm have lost their calling function. However, they have neither disappeared, nor has the orgasm itself. Hence, a reasonable assumption follows: this structure began to provide a different kind of care, namely choosing and holding the best partner. To use a metaphor, one can say that the body of a woman, through the highest degrees of pleasure and emotional experience, sends a signal to the brain: “This is whom I want!” [4].

By the way, it is no coincidence that the involuntary and optional nature of the female orgasm has its analogy in the involuntary and optional nature of male arousal and erection. In the same way, the penis sends a signal to the male brain: “I want it now!” The same principle of selectivity applies here, though in a different register. An orgasm, undoubtedly, is a powerful positive reinforcement of the love and sexual connection with this very man (further, we will talk about the syncretism of female sexuality). All this complex of feelings and desires is activated and concentrated on the partner who delivered extraordinary pleasure.

According to a well-meaning model of the “naturalness” of monogamy, we could say that it is always about the groom, the legitimate spouse, and the father of future children. However, even here, it is not simple. Given that women are almost twice as likely to have orgasms with their lovers as with their husbands. Thus, orgasm is accompanied by high retention of sperm (within two minutes after a male orgasm) [10, 11].

A female orgasm serves both to select a partner with the best (most suitable) genes and strengthen the couple. Orgasm promotes conception during the period of maximum fertility with the gene-optimal partner and strengthens the relationship with the permanent partner (spouse) through an increase in oxytocin levels outside of this fertile window period. It is just when special attention and experience by the man are required to induce orgasm in the woman. Accordingly, women of different types share the importance and weight of these functions. For the “unfaithful,” practicing a short-term mating strategy, orgasm promotes fertilization and perception of the best genes of the chosen one. For “faithful” women, deprived of the chance to benefit reproductively from extramarital sex, orgasm serves to strengthen the bond with a permanent partner (spouse) [23].

There is another original concept that rejects the purely biological (“good genes”) and mercantile (“resources from a partner for oneself and children”) adaptive meanings of the female orgasm. Instead, R. Prum believes that women’s orgasm reproduces in generations as a self-valued pleasure and coevolves with men’s ability to deliver it.

“In the Pleasure Happens mechanism, we must focus on the coevolution of the subjective experience of pleasure with the attributes that produce that pleasure. It means recognizing that the pleasurable experience of mate choice itself is still rarely recognized in the scientific literature” ([24], p. 180).

The usual criticism of this concept for its superficiality does not mean that the more profound reasons must necessarily be biological or self-serving. An essential characteristic of the female orgasm is its solid emotional intensity, connected with feelings of love and commitment to the partner. A woman’s violent manifestation of pleasure usually does not leave her partner indifferent (if he is capable of any feelings at all). On the contrary, this lure works for both: one wants more and more. However, there are no guarantees. Not every man can be attracted to it, not every spouse can be discouraged from left thoughts, but female orgasm is one of the most robust means of excitement and strengthening mutual feelings in the partner, often exceeding daily feeding of tasty food.

The female orgasm is not firmly attached to feelings of love and commitment: not every time a woman experiences it in coitus with her beloved partner, and sometimes she can get such pleasure with an attractive man even in a one-time encounter. However, the connection between feeling and orgasm in women is stronger and more frequent than in men. R. Prum uses the concept of “pleasure,” but it is correct to speak of all-absorbing delight, ecstasy, joy, and happiness. A woman’s sense of love and commitment to her partner increases the likelihood of orgasm, and each orgasm with him reinforces that feeling. The feedbacks and signals “from body to brain” and “from brain to body” are enhanced here.

Is it necessary to explain why emotionally, psychophysiologically, and sexually satisfied, in other words, happy and confident women and their offspring, get advantages in sexual selection? I will point only to such characteristics as attractiveness, friendliness, non-conflict, and a high level of social membership. Already this, far from complete, list of advantages is enough to explain the development and reproduction of women’s ability to experience orgasm with the person they love.

Is this, relatively standard for evolutionary biology, a sufficient explanation? Why do not women gain the ability to imitate orgasm with the same beneficial effect, but without so much energy expenditure? By the way, many do. However, for some reason, women’s ability to orgasm does not diminish, even on the contrary. There is something mysterious and disinterested in this, which requires an independent explanation and comprehension.


8. Female syncretism and male duality

In women, erotic, sexual attraction is usually inextricably linked with emotional commitment, encompassing personality and imagination, mind, attention, and memory. On the other hand, erotic and sexual attraction in men is closely linked to visual perception and imagination but is often weakly coupled with other cognitive functions, including intellectual and value spheres.

Let us call these features of sexuality female syncretism and male duality. The problem is that they are used to explain many things while they have no evolutionary explanation.

Note that the primates closest to humans do not have such a pronounced difference. The stability of gibbons’ pairs suggests that both males and females are “soul and body” committed to each other, i.e., both are similar to the most faithful and loving woman. It is doubtful that our distant ancestors were similar to gibbons in this respect, but even in such an unlikely case, there is no way to explain why men have lost such an admirable quality.

Among the chimpanzees and bonobos closest to us in sexual behavior, our male type, or rather the “lower” half of it, is characteristic for males and females with a fair amount of levity regarding the early satisfaction of their needs. All this suggests that the key to the explanation is the complex phenomenon of female syncretism, whereas the absence or rejection in males would be easier to explain.

What could be the original form, the source of the fantastic and all-encompassing female love, the fusion of the emotions of commitment, eroticism, and sexual attraction?


9. The key to female happiness

In keeping with the Freudian tradition, let us turn to childhood. What can we surmise about the feelings of little boys and girls in the distant ages of the rare hunter-gatherer groups, surrounded by all kinds of risks, threats, calamities from predators and strangers, natural disasters, cold, and hunger?

On the one hand, probably the strongest were fear and anxiety, fear of being left alone, and on the other hand, joy and contentment, intense experiences of happiness to be again under the protection of relatives and friends. This pendulum of fear of being left alone and happiness of being protected serves as a basis for forming emotional complexes aimed at mom, dad, and other relatives — protectors.

For the youngest, the mother provided the comfort of protection, as it still is today. In large groups living together, aunts, older sisters, grandmothers play the same role [25]. Boys and girls, as they grow up, understand and feel that the father still provides the principal protection (also with his brothers and companions). For the most part, girls remain emotionally committed to their mothers and imitate them, often inheriting patterns of their relationships with men. However, then, in girls and women, there is a crucial transformation of feelings: they transfer filial love, commitment to the father (or close adult male protectors) to peers — guys, young men, men — as objects of love, erotic and then sexual attraction. It is evidenced by the well-known acuteness and intolerability of female trauma when a loved one leaves — the fear of being left alone, without protection and support is related to childhood fears.

It is also known that the more a girl loves her father, the more like him she will look for a man as her life partner. Conversely, the father’s absence and a lousy relationship usually lead to difficulties in a woman’s personal life. Again, this shows the paramount importance of a daughter’s love for her father or lack thereof.


10. Duality as a cost of manhood and the humanism of evolution

What was and is happening to boys? Love for the mother cannot lead to identification with her and imitation. Such behavior has long been subject to strict social control through ridicule (“Don’t be a sissy! You behave like a girl!”). Boys usually aspire to imitate their fathers and prestigious adult men, which is quite natural. Sometimes, as adults, they also choose girlfriends who look like their mother, though this tendency is not pronounced in girls.

Why is it that instead of syncretism, men develop duality — the ability to divide between “high” love for some women, admiration for them, and “low,” purely sexual drive, even “lust” for others?

At first glance, there is an apparent symmetry: girls are forced to give up their beloved fathers as a partner, but boys are also forced to give up their beloved mothers. However, there is also an essential asymmetry here. Girls, growing up, retain an integral emotional complex of love and commitment, turning it on their peers (usually older than themselves, which, incidentally, is quite natural), while boys do not retain this integrity. Why not?

The principal solution is that in girls and women, the fear of loneliness with the need for protection and support remains the same during adulthood, while in boys and men, the primary commitment structure was destroyed and suppressed at some period of anthropogenesis. Since then, this drama has repeated with varying (un)success in the ontogenesis of every man.

It is typical for young boys to want to “marry” their mother. The subsequent understanding of the impossibility of fulfilling this desire connects with a forced denial of one’s weakness, of the recognition that one suffers from loneliness and without a mother. Girls are allowed to be weak and defenseless, but boys are not. Here, as usual, sexual selection and social, the cultural press were at work. Boys, adolescents who were unable to readjust, overcome fear or at least hide it, felt contemptuous. They were very likely not to pass the initiation test, were not considered “real men,” and suffered a complete failure in the reproductive aspect. Other boys more widely could suppress fear. Later, they presented themselves as strong and courageous warriors, hunters, defenders. Naturally, such men were more successful in spreading their genes. In parallel, the masculine patterns of male behavior were spread and transmitted through cultural channels.

This “self-destruction with realignment” was also directly related to men’s attitudes toward the mother. Her image usually moves into the mental realm of high feelings (it is not without reason that insulting the mother, especially in the sexual modality, in most cultures is the most humiliating for men and requires repulsion, even revenge). The same mental realm also serves as the abode of beautiful, inaccessible, forbidden women. They should be nobly protected and served.

Violent sexual needs in adolescence arise and grow apart from the realm of inaccessible beautiful ladies and high feelings. Instead, these “low” needs are more related to the motives of male self-assertion through aggressive “conquest,” with claims to power and domination, with possible options of coercion, violence, or the simple purchase of sex.

Mature men (alas, not all of them) can combine high feelings of love, adoration, and sexual attraction to their wives and girlfriends. However, it is precisely the connection that is initially separate (!), so it is not uncommon for either part or the other to fall away. Respect, adherence may last longer, or vice versa, the sexual attraction of the spouse, remains, while love for her, respect, solidarity disappear. For women, the cooling-off occurs differently: someone she no longer respects or loves she no longer needs in bed.

For all the diversity of evolutionary biology concepts and the paleopsychology of sexuality, they have a common denominator— the premise of the selfishness of every sex, individual, and genome: the sociobiology “bible” title “The Selfish Gene”is not at all accidental. Even the subsequent wave of evolutionary explanations of human altruism still derives such behavior from the same selfishness.

In this respect, the notorious “uselessness” of the female orgasm, the difficulty, and insufficiency of explaining it through egoistic motives must be reinterpreted. Metaphorically, the female orgasm is a brave and even a pretty humane attempt of evolution to somehow compensate, to overcome the forced and depressing dualism — the cleavage in men’s sexual life. Rejoicing and being proud that he delivered such a strong and impressive pleasure to a woman, her partner receives at least a part of that fullness and depth of love feelings, to which women are capable.


  1. 1. Symons D. The Evolution of Human Sexuality. Oxford: Oxford Univ. Press; 1979
  2. 2. Fisher HE. Anatomy of Love. New York: Fawcett Columbine; 1992
  3. 3. Halliday T. Sexual Strategies. Chicago: University of Chicago Press; 1980
  4. 4. Barash D, Lipton J. The Myth of Monogamy. New York: Fidelity and Infidelity in Animals and People, Henry Holt and Company; 2001
  5. 5. Diamond J. The third chimpanzee: The evolution and future of the human animal. New York: Harper Perennial; 2006
  6. 6. Beckerman S, Valentine P, Introduction: The concept of partible paternity among native south Americans. In: Beckerman S, Valentine P, editors. Cultures of Multiple Fathers: The Theory and Practice of Partible Paternity in Lowland South America. Gainesville: Univ. Press of Florida; 2002:1-13
  7. 7. Christopher R, Jethá C. Sex at Dawn: The Prehistoric Origins of Modern Sexuality. New York: Harper Collins; 2010
  8. 8. Sherfey M, The J. Nature and Evolution of Female Sexuality. New York: Random House; 1972
  9. 9. Thornhill R, Gangestad SW. The Functional Design and Phylogeny of Women’s Sexuality. In: Shackelford TK, Hansen RD, editors. The Evolution of Sexuality. New York: Springer; 2015. pp. 149-184
  10. 10. Buss D. The evolution of desire: Strategies of human mating. New York: Basic Books; 2016
  11. 11. Miller GF. The Mating Mind: How Sexual Choice Shaped the Evolution of Human Nature. New York: Doubleday; 2000
  12. 12. Baker R. Sperm wars: Infidelity, sexual conflict, and other bedroom battles. London: Fourth Estate; 1996
  13. 13. Bellis M, Baker R. Do Females Promote Sperm Competition: Data for Humans. Animal Behaviour. 1990;40(5):997-999
  14. 14. Birkhead T. Promiscuity: An evolutionary history of sperm competition and sexual conflict. New York: Faber and Faber; 2000
  15. 15. Dixson A, Anderson M. Sexual Selection and the Comparative Anatomy of Reproduction in Monkeys, Apes and Human Beings. Annual Review of Sex Research. 2001;12:121-144
  16. 16. Lindholmer C. Survival of Human Sperm in Different Fractions of Split Ejaculates. Fertility and Sterility. 1973;24(7):521-526
  17. 17. Harcourt AH. Sperm Competition and the Evolution of Nonfertilizing Sperm in Mammals. Evolution. 1991;45(2):314-328
  18. 18. Pusey AE. Of apes and genes. In: de Waal FM, editor. Tree of Origin: What Primate Behavior Can Tell Us About Human Social Evolution. Cambridge, MA: Harvard Univ. Press; 2001
  19. 19. Lloyd EA. The case of the female orgasm: Bias in the science of evolution. Cambridge, MA: Harvard University Press; 2005
  20. 20. Semple S. Individuality and Male Discrimination of Female Copulation Calls in the Yellow Baboon. Animal Behaviour. 2001;61(5):1023-1028
  21. 21. Pradhan GR et al. The evolution of Female Copulation Calls in Primates: A Review and a New Model. Behavioral Ecology and Sociobiology. 2006;59(3):333-343
  22. 22. Pound N. Male Interest in Visual Cues of Sperm Competition Risk. Evolution and Human Behavior. 2002;23(6):443-466
  23. 23. Wheatley JR, Puts DA. Evolutionary science of female orgasm. In: Shackelford TK, Hansen RD, editors. The Evolution of Sexuality. New York: Springer; 2015. pp. 123-148
  24. 24. Prum RO. The Evolution of Beauty, How Darwin’s Forgotten Theory of Mate Choice Shapes the Animal World and Us. New York-Toronto: Doubleday; 2017
  25. 25. Hrdy SB. Mother Nature: A History of Mothers, Infants and Natural Selection. Boston: Pantheon Books; 1999

Written By

Nikolai S. Rozov

Submitted: January 13th, 2022 Reviewed: January 14th, 2022 Published: March 8th, 2022