Research: Evolutionary Perspectives on Intergenerational Sexuality

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This article, unlike most of our research articles, has been written in standard format as opposed to that of an anthology. This owes to the highly theoretical nature of the topics discussed.

While the evolutionary logic of intergenerational sexual behaviour and hebephilic attraction towards pubertal adolescents of the opposite sex is easily explained by fertility potential of such behaviour (see mentions of hebephilia), the explanation of intergenerational attractions toward prepubertal children (pedophilia/pedosexuality), or adolescent homosexual partners (pederastic inclination), or the very existence of prepubertal child sexuality, is less obvious.

The emergence of such sexuality has several evolutionary explanations with varying degrees of evidence, which come from ethology and neuroscience. There are suggestions that, in our evolutionary past, pedosexual behaviors could have had some evolutionary functions or been an evolutionary by-product of human sexuality development.

A by-product of lack of success in male competition

One hypothesis is that if a male chronically feels inferior to others and is afraid of other adults, then his sexuality towards adults may be suppressed and redirected towards children, because children do not cause fear, and next to them the male feels his strength and superiority. Male sexuality is more associated with dominance and this may explain the greater prevalence of attraction to children among men than among women.

"Nest helper" hypothesis

The concept of "nest helper", is an explanation of a few individuals within a group being nonreproductive, yet aiding their group's survival. They may be affectionately disposed and caring towards others without reproducing, since this promotes the reproduction of peers who share some of the same genes due to being genetic relatives in the group. Due to sexual competition and the costs of human reproduction, not every individual can reproduce, hence there are indirect genetic benefits of "nest helping" that may overcome benefits of direct reproductive efforts for some individuals. This evolutionary hypothesis applies to both exclusive homosexuality and exclusive pedophilia, although due to a lack of investigation, there is at present little evidence for it (Feierman, 1990).

Fertilization

For many primates, sexual behavior requires learning. Therefore, in some species, adult primates who have sexual contact with juveniles may help them develop sexual skills. In addition, sex can trigger the onset of fertility. Such a function could have played a role in the human evolutionary past (Dienske, 1990). In some species, this function has built in to that extent that without early sexual experience with an adult an individual grows up unable to conceive ("In the squirrel monkey (Saimin), captivity-raised individuals of both sexes in mixed-sex peer groups were not even able to conceive unless they had been allowed, when they were juveniles, to have sexual contact with opposite-sex adults (Hopf, 1979, personal communication).").

“Peripheralize and attract strategy”

The emergence of nonexclusive pedophilic interest could be due to males experiencing selection pressure to display affiliative behavior towards minors. Such a display aims to convince fertile females that the male is ready for paternal investment, thus giving advantages in access to the fertile female (Taub, 1990).

Sex as a buffer for aggression

Ethologist Irenäus Eibl-Eibesfeldt suggested that the interconnection between sex and dominance is the basic ("reptilian") way of vertebrate sexuality organization. Aggression and dominance acquired a functional connection with male sexuality due to the fact that aggressive and dominant males tended to win in sexual competition. In contrast, submission was embedded in female sexuality. The submissive posture of the female ready for mating is a stimulus to transform male’s aggressive drive to the sexual drive. This prevents injuries and allows mating to occur. Thus aggression, dominance and submission were sexualized, and sexuality acquired the ability to buffer aggression in hierarchical relationships. (The manifestation of that ability is that the appeasing posture of a defeated enemy in animals often resembles the posture of a female ready to mate). Eibl-Eibesfeldt supposed that it is possible that this function could be partly transferred into the adult-juvenile hierarchical relationship (Eibl-Eibesfeldt, 1990).

Sex for food sharing

The reduction of social tension mediated by sociosexual contact is widespread in the communities of human closest relatives, the Bonobos. The tension arises in situations of competition or inequality referring to any kind of resources such as food, access to reproduction or any interesting stimulus matter. In addition to the reconciliation effect, sexual contacts allow them to willingly share resources with one another. Ethologist Frans de Waal pointed that this mechanism works for individuals of any status, sex and age, including contacts between adults and infants. Via this mechanism, adults share food with juveniles who are not their descendants and are not of reproductive interest. The emergence of this mechanism presumably occurred as a result of an evolutionary shift in relationships between males and females towards the more tolerant and equal in the case of Bonobos (de Waal, 1990). Among most other primates except for humans, cases of adults, especially males, sharing food with another's offspring are quite rare (Mackey, 1990).

Frans de Waal suggests that our ancestor’s sexual behavior may have been similar to Bonobo's. This sex-for-food mechanism then allowed females to exchange sex for male commitment and paternal investment, thus giving rise to the human nuclear family. And subsequently, the very development of the nuclear family led to an increasing restriction of sex functions to heterosexual reproductive bonding only (de Waal, 2006).

Sex as an attachment promoter

In addition to the “reptilian” connection between sex and dominance, Eibl-Eibesfeldt described another way of sexuality organization. That evolutionary later way is the interweaving of sex and attachment, which is typical for birds and some mammals forming long-term reproductive alliances. The ability of males to form attachment and exhibit caring behavior to a sexual partner is highly beneficial for females. Human evolution went through an increase in the maturation time of offspring, which led to huge reproductive costs for females. Thus, there was a particularly strong sexual selection of males, in which sexual desire was accompanied by consistent caring behavior towards the female and her offspring. This attachment to a sexual partner may be evolutionarily linked to child-parent attachment (in some species, this connection is manifested in the features of sexual courtship rituals containing signs of childish behavior, which function to induce caring behavior and affection in a sexual partner). So according to this theory, the functional system of parental care and the functional system of mating became interconnected. Eibl-Eibesfeldt wrote that romantic love occurs through the fusion of parental care and sexual desire, and this fusion is an antecedent for children and adolescents to evoke romantic feelings in some adults (Eibl-Eibesfeldt, 1990 ).

In line with Eibl-Eibesfeldt, ethologist Herman Dienske argues that, in the course of evolution, due to the ability of human females to conceal ovulation and to be continuously sexually receptive, male sexual interest has evolved in turn to foster consistent male proximity (to invest in offspring that take so long to mature), and subsequently could promote male proximity with the infant (Dienske, 1990). Indeed, the repertoire of pedosexual behavior observed in humans, besides sexual actions, may also include caring behavior: comforting/caressing, feeding, grooming (body care such as washing or massage), protecting, teaching (Feierman, 1990).

Mentions of the hypothesis in mainstream literature

This hypothesis is also mentioned in modern scientific encyclopedias:

• “the evolutionary explanation behind the origin of pedophilia refers to the fusion of two evolutionarily ancient adaptive systems – reproduction and nurturing. Money (1990) states that a pedophile’s relationship to a child qualitatively, and also neurologically, resembles a blend between parental and erotic love. Likewise, it can be linked to the close cohesion between these two systems that can be observed also between phylogenetically close species.” (Klapilová & Bártová 2017, p. 7444 ).
• ”The founder of the human ethnology field, Irenäus Eibl-Eibesfeldt (1973), directly warns about the type of affiliative-erotic relationship that connects to the composition of long-term partnership, which was developed both in mammals and birds together with nurturing behavior, and therefore it is not surprising that they are occasionally mixed in humans.” (Klapilová & Bártová 2017, p. 7444 ).
• “We would entertain the hypothesis proposed separately by Eibl-Eibesfeldt (1990) and by Money (1990) that two innate biosocial propensities – caregiving and sex-mating – have become fused in the course of ontogeny in those who display the paedophilic orientation.” (Stevens & Price 2016, p. 210 ).
• “...affiliative erotic love, as Eibl-Eibesfeldt points out, itself evolved in birds and mammals together with the development of parental care-giving behaviour. ‘Since human adult/adult romantic love is derived by phylogeny from parent care-giving behaviour,’ asserts EiblEibesfeldt, ‘it is easily seen how, in some adult humans, the feeling of love toward children has been retained and eroticised, which is the true meaning of the term “pedophilia”.’ “ (Stevens & Price 2016, p. 213 ).

Neurological and endocrinological aspects

Human sexuality researchers have confirmed the neurobiological interconnection of sexual and attachment systems. The release of oxytocin, vasopressin and prolactin, hormones associated with parental behavior, during sex and orgasm stimulates the formation of attachment, altruistic behavior and care for a partner. The reverse is also true: trusting and caring relationships can evoke sexual interest (Dewitte & Marieke, 2012 ; Fleischman, 2021 ).

Two decades after Eibl-Eibesfeldt suggested that the neural systems of sex and care are relatively more connected in people who are sexually attracted to children, neuroscientists have found some experimental evidence for that. Brain structures responsible for social connections, altruistic and parental motivation (such as the left anterior insula), in people with pedophilic interest, respond to infant stimuli more intensively, receiving reinforcement from the neural circuits responsible for mating. In addition, a greater connection between parental and mating systems is characteristic of males, which is explained by evolutionarily different ways of forming maternal and paternal investments (Ponseti et al., 2018 ).

Complementary behavior among minors

The hypothesis of pedophilic attraction as a promoter of affection and care is confirmed by the existence of complementary behavior of minors, who often show initiative and willingness for sexual relations with adults. It’s assumed that such a behavior could function to receive affection and extra resources not available from the child's default caregiver. This testifies to the evolutionarily beneficial and reciprocal essence of intergenerational attraction (Klapilová & Bártová, 2017 ; Stevens & Price, 2016 ; Rind, 2013 ).

• “The child’s adaptive behavioral function to demand nurture from adults and his prospective urge to perform sexual activities is not mentioned too often. Still, it is a rather widespread behavior across cultures and historical periods that can help the child receive extra resources not available from their own parents. It would therefore be a complementary strategy – from the pedophile’s side, there is the eroticization of nurturing behavior and attraction to signalization that encourages caretaking, whereas from the child’s side, it is a functional, environmentally conditioned strategy that brings benefits in the form of resources and possibly even acquisition of sexual experience and calibration of child sexuality” (Klapilová & Bártová 2017, p. 7445 ).
• “it is undeniable that many children in our society – especially those in boarding schools and childrens’ homes – suffer from ‘parent hunger’. They are what Mia Kellmer-Pringle has called ‘touch-hungry children’. It is possible that the care-eliciting ‘phylism’ in these children may become eroticized just as the care-giving phylism may be eroticized in adult paedophiles. Thus, children starved of parental affection may compete for the love and attention of adults in their environment by using erotic solicitation as a strategy for survival. To suggest this possibility is not to excuse adults who exploit the emotional needs of children for their personal gratification but to provide an evolutionary explanation as to how and why erotic bonds between adults and juveniles may occur. We would propose that both care-eliciting and care-giving phylisms can be eroticized.” (Stevens & Price, 2016, p. 214 ).

Evolutionary by-product of human neotenization

Another factor of pedosexual attraction emergence is a human neotenization. The evolutionary advantage of retaining neotenic (childish) traits which elicit nurturing responses from adults, results in the retention of neotenic genetic traits due to sexual competition. Therefore such traits become sexually attractive. That leads to the observable progressive neotenization of humans in comparison with ancestors and subsequently increases likelihood of juveniles being sexually attractive. Since fertile females retained juvenile traits into their fertile years, the line between fertile and infertile female age became blurred. Thus, some males become oriented toward females who are too young for reproduction (Feierman, 1990).

Mentorship-Bonding/Enculturation-Alliance Hypothesis

On the basis of previously available evolutionary explanations (Mackey, 1990 ; Muscarella, 2000 ; Kirkpatrick, 2000 ; Neil, 2009), Bruce Rind developed a hypothesis explaining the most widely documented type of male homosexuality in human history, namely pederasty (the relationship between a man and a peripubertal/adolescent boy) (Rind, 2013 ).

It is assumed that the evolutionary function of man-boy sexual relationships comes from our evolutionary past, when the environment was very different from the modern one. Humans have had a long evolutionary history as hunter-gatherers. This time was characterized by intergroup warfare and the hunting of large animals. To do this, it was necessary to form close-knit same-sex male groups, to form specific male skills of war and hunting, and to maintain the specific masculine culture of this group. This created a selection pressure to create a mechanism to facilitate such rallying, recruitment and enculturation of new members, which is a long-term and labor-intensive undertaking. It is hypothesized that the sexual attraction between a boy and a man became such a mechanism, through the ability to form a strong emotional connection, prompting the mentor to teach and care, and the boy to seek training and a role model.

The evolutionary benefit of such a mechanism is assumed both at the individual level (for the junior this is training, protection, and promotion in the male hierarchy, for the adult this is the expansion of the network of alliances) and at the group level (the clan received a reliable replenishment of group members, well-prepared, enculturated and committed to the culture of the group, which gave a competitive advantage).

This hypothesis is supported by cross-cultural studies, where a variety of independent cultures demonstrate the prevalence of sexual relations between men and boys of peripubertal age. These relationships are built into these cultures and are part of growing up and becoming a man. The readiness, desire and initiative for sexual contact comes not only from adult men, but also from boys, and this is recorded as a typical phenomenon in these cultures. This also confirms the existence of an evolutionary benefit for younger participants.

Moreover, this attraction is not associated with reproductive losses, unlike exclusive homosexuality. It is typical of all these cultures that, upon reaching adulthood, men get wives and at the same time have sexual relations with boys themselves. It is assumed that this ability of the average heterosexual male to experience pederastic attraction is specific to our species.

But this ability is optional (facultative). That is, unlike obligate heterosexual attraction, pederastic interest is to a large extent activated or suppressed by the social environment. This explains the fact that there is a sharp difference in the prevalence of pederastic behavior and attraction between cultures, and the fact that in modern Western cultures it does not manifest itself widely.

See also

• Debate Guide: Evolutionary logic
• Intergenerational Relationships in History
• Intergenerational Sexual Behaviors in Animals