Kin-directed Altruism Research Articles

Recalled Childhood Separation Anxiety in Relation to Sex, Sexual Orientation, and Gender Identity in Thailand

ABSTRACT Same-sex sexual attraction is an evolutionary paradox. It is influenced by genes but also associated with reduced reproduction. An altruistic disposition toward kin could increase relatives’ reproduction, thus addressing this paradox. Developmentally, such a disposition may manifest as anxiety during separation from kin. This hypothesis has been supported among androphilic (i.e. sexually attracted to males) males, but few similar studies of gynephilic (i.e. sexually attracted to females) females exist. We examined recalled childhood separation anxiety in Thailand and employed the largest and most sexually and gender-diverse sample to date (N = 1403). Among heterosexuals, men recalled less concern for parents’ and siblings’ well-being during separation than women. Androphilic males evidenced elevated concern for parents’ and siblings’ well-being during separation, and transfeminine androphilic males known as sao praphet song reported heightened anxiety when separated from parents. Among females, transmasculine gynephilic females known as toms recalled less concern about parents’ well-being during separation than feminine females who are attracted to toms and known as dees. Bisexual women recalled less anxiety when separated from parents than dees and lesbian and heterosexual women. These findings suggest a disposition toward heightened kin-directed altruism is evident in childhood among androphilic males, but not gynephilic females.

A Test of the Kin Selection Hypothesis for Female Gynephilia in Thailand.

Female gynephilia (i.e., sexual attraction to adult females) is considered an evolutionary paradox because it reduces direct reproduction, yet it is influenced by genetic factors and has persisted over time and across different cultures. The Kin Selection Hypothesis proposes that same-sex attracted individuals offset their lowered direct reproduction by engaging in kin-directed altruism that increases the reproduction of close genetic relatives, thereby enhancing inclusive fitness. Previous research on male same-sex attraction found evidence to support this hypothesis in some cultures. The present study employed a Thai sample to compare altruistic tendencies towards kin and non-kin children in heterosexual women (n = 285), lesbian women (n = 59), toms (i.e., masculine gynephilic females who take on a nonbinary gender identity; n = 181), and dees (i.e., feminine gynephilic females who are attracted to toms; n = 154). The Kin Selection Hypothesis of same-sex attraction predicts that gynephilic groups would show increased kin-directed altruism compared with heterosexual women, but we did not find evidence supporting this prediction. Instead, the tendency to invest more towards kin than non-kin children was more exaggerated in heterosexual women than lesbian women. Also, heterosexual women showed greater dissociation between kin and non-kin altruistic tendencies compared with toms and dees, which may suggest the former's cognition is better attuned for kin-directed altruism. Thus, the present findings were contrary to the Kin Selection Hypothesis for female gynephilia. Alternative explanations regarding the maintenance of genetic factors predisposing individuals to female gynephilia are discussed and require further investigation.

Kin-directed altruism and the evolution of male androphilia among Istmo Zapotec Muxes

Male androphilia (i.e., sexual attraction and arousal to adult males) is considered an evolutionary puzzle because it reduces direct reproduction, but is influenced by genetic factors, reliably occurs across cultures, and has persisted over evolutionary time. The kin selection hypothesis states that genes for male androphilia can be maintained in a population if the costs of not reproducing directly are offset by enhancing the reproduction of kin. We tested this hypothesis among the Istmo Zapotec of Oaxaca, Mexico, where transgender and cisgender androphilic males are known as muxe gunaa and muxe nguiiu , respectively. We compared altruistic tendencies towards kin and non-kin children between muxe nguiiu ( n = 106), muxe gunaa ( n = 106), gynephilic men (i.e., men sexually attracted and aroused to adult females; n = 172), and androphilic women ( n = 130). We also assessed whether the sisters of muxes ( n = 96) reported receiving more childcare support from their muxe sibling compared to women with only gynephilic brothers ( n = 65). The results showed that cisgender and transgender muxes reported more kin-directed altruistic tendencies than men. Muxe nguiiu also reported more kin-directed altruistic tendencies than women. When controlling for altruistic tendencies towards non-kin children, both muxe types exhibited more kin-directed altruistic tendencies than men and women. Women with muxe siblings reported receiving more childcare support from these relatives compared to women with only gynephilic brothers. These findings provide support for the kin selection hypothesis and highlight its potential role in elucidating the evolutionary paradox of male androphilia.

Striving for Prestige in Samoa: A Comparison of Men, Women, and Fa’afafine

ABSTRACTIn numerous non-Western cultures around the world, a small but meaningful proportion of individuals occupy alternative gender categories beyond the man/woman binary. A substantial body of past research has shown that feminine, same-sex attracted males in Samoa—a nonbinary gender known as fa’afafine—are more altruistic toward their nieces and nephews than are Samoan men and women. The present study examined the degree to which these kin-directed altruistic tendencies of fa’afafine are motivated by striving for prestige, and hence demonstrating value, within their family. Results showed that cisgender men and women do not differ in the degree to which they seek familial recognition of their altruistic behavior toward nieces and nephews. However, compared to men, fa’afafine sought significantly more acknowledgment of this altruism. These results illustrate one proximate cognitive mechanism for the elevated kin-directed altruism of fa’afafine and highlight the importance of the sociocultural context in which these motivations develop.

Family ties: the multilevel effects of households and kinship on the networks of individuals.

Among social mammals, humans uniquely organize themselves into communities of households that are centred around enduring, predominantly monogamous unions of men and women. As a consequence of this social organization, individuals maintain social relationships both within and across households, and potentially there is conflict among household members about which social ties to prioritize or de-emphasize. Extending the logic of structural balance theory, I predict that there will be considerable overlap in the social networks of individual household members, resulting in a pattern of group-level reciprocity. To test this prediction, I advance the Group-Structured Social Relations Model, a generalized linear mixed model that tests for group-level effects in the inter-household social networks of individuals. The empirical data stem from social support interviews conducted in a community of indigenous Nicaraguan horticulturalists, and model results show high group-level reciprocity among households. Although support networks are organized around kinship, covariates that test predictions of kin selection models do not receive strong support, potentially because most kin-directed altruism occurs within households, not between households. In addition, the models show that households with high genetic relatedness in part from children born to adulterous relationships are less likely to assist each other.

Elevated Kin-Directed Altruism Emerges in Childhood and Is Linked to Feminine Gender Expression in Samoan Fa'afafine: A Retrospective Study.

Androphilia refers to sexual attraction toward adult males, whereas gynephilia refers to sexual attraction toward adult females. The kin selection hypothesis posits that androphilic males help kin increase their reproductive output via kin-directed altruism, thus offsetting their own lowered reproduction and contributing to the fitness of genes underpinning male androphilia. Support for this hypothesis has been garnered in several Samoan studies showing that feminine androphilic males (known locally as fa'afafine) report elevated willingness to invest in nieces and nephews in adulthood. Also, recalled childhood kin attachment and concern for kin's well-being are elevated among Canadian androphilic males (i.e., gay men) and positively associated with childhood feminine gender expression. This study examined whether these childhood patterns were cross-culturally consistent and associated with adulthood kin-directed altruism in a Samoan sample. Samoan gynephilic men, androphilic women, and fa'afafine (N=470) completed measures of recalled childhood kin attachment and concern for the well-being of kin, recalled childhood gender expression, and willingness in adulthood to invest in nieces and nephews. Fa'afafine recalled elevated anxiety due to separation from kin relative to men and elevated concern for kin's well-being relative to both men and women. Within groups, these characteristics were most robustly associated with childhood feminine gender expression and willingness in adulthood to invest in nieces and nephews among fa'afafine. These findings are consistent with the kin selection hypothesis and the adaptive feminine phenotype model, which proposes that a disposition toward elevated kin-directed altruism among androphilic males is associated with feminine gender expression.

Femininity and Kin-Directed Altruism in Androphilic Men: A Test of an Evolutionary Developmental Model.

Androphilia refers to sexual attraction and arousal toward males whereas gynephilia refers to sexual attraction and arousal toward females. This study tested the adaptive feminine phenotype model of the evolution of male androphilia via kin selection, which posits that the development of an evolved disposition toward elevated kin-directed altruism among androphilic males is contingent on the behavioral expression of femininity. Gynephilic men, androphilic women, and androphilic men (N = 387) completed measures of childhood and adulthood gender expression and concern for kin's well-being. Adulthood femininity correlated positively with uncle/aunt-like tendencies among androphilic men and women. Although androphilic women reported greater willingness to invest in nieces and nephews than gynephilic and androphilic men, mediation analyses indicated that adult femininity completely mediated these group differences. In addition, changes in the expression of femininity between childhood and adulthood were associated with parallel changes in concern for the well-being of kin among androphilic men. Thus, these findings suggest that femininity is key to the expression of kin-directed altruism among androphilic males and may have been important in the evolution of male androphilia.

Societal Norms Rather Than Sexual Orientation Influence Kin Altruism and Avuncularity in Tribal Urak-Lawoi, Italian, and Spanish Adult Males

Homosexual males could balance their low fitness by increasing benefits to relatives either through kin-directed altruism or by avuncularity (altruistic behavior toward the children of siblings). Evidence in support of kin selection and avuncularity includes the fact that homosexuals seem to be more empathic and altruistic than heterosexuals. Other studies have not confirmed behaviors that increase kin altruism in homosexuals. We explored altruistic behavior and avuncularity in a sample of 278 subjects, either homosexual or heterosexual, from three populations: Italian, Spanish, and Urak-Lawoi, a Southeast Asian tribal population. Among the Urak-Lawoi, the kathoeys, androphilic men who dress and behave as women, were compared with heterosexuals. All populations were rated for societal norms on the expression of affiliative behavior. No greater kin altruism or avuncularity among the kathoeys or in homosexuals in either Mediterranean population was found. Greater avuncularity and kin-directed altruism, independent of sexual orientation, were found among the Urak-Lawoi, and these traits were the least prevalent among the Italians, corresponding to different societal norms. The increase in kin altruism and avuncularity was associated in all males with societal differences and norms on general altruism toward nonkin children, suggesting it is not an adaptive design to maintain homosexuality in humans.

Elevated childhood separation anxiety: An early developmental expression of heightened concern for kin in homosexual men?

This study presents data bearing on an evolutionary developmental model of male homosexuality. This model hypothesizes that a predisposition toward elevated kin-directed altruism among homosexual males is expressed in childhood as elevated concern for close attachment figures (e.g., parents) and proximally influenced by the concomitant behavioral expression of femininity. We examined whether homosexual males recalled such elevated concern for parents during childhood and considered its association with recalled childhood gender behavior. Heterosexual and homosexual males and females (N=524) provided measures of recalled childhood gender behavior, concern about parental wellbeing, and other potential sources of separation anxiety. Heterosexual males experienced significantly less anxiety about parental wellbeing than all other groups. Recalled separation anxiety was positively correlated with childhood femininity for heterosexual females and homosexual males. The heterosexual sex and male sexual orientation differences in concern about parental wellbeing were accounted for by childhood feminine behavior. These findings are consistent with the proposed evolutionary developmental model. We discuss possible proximate influences that facilitate the development of this putative evolved predisposition toward elevated kin-directed altruism among homosexual males as well as limitations and future directions.

Evidence of Cognitive Biases for Maximizing Indirect Fitness in Samoan Fa’afafine

The kin selection hypothesis posits that male androphilia (i.e., sexual attraction to males), although detrimental to reproduction (i.e., direct fitness), has persisted and evolved because androphilic males compensate by increasing their indirect fitness via increased investment in kin. In previous studies, Samoan androphilic males (known locally as fa'afafine) reported elevated avuncular (i.e., uncle-like) tendencies compared to Samoan gynephilic (i.e., sexually attracted to females) men. Their avuncular tendencies were also greater than the materteral (i.e., aunt-like) tendencies of androphilic women. The present study examined whether the avuncular cognition of fa'afafine was enhanced for maximizing indirect fitness. To do so, it examined whether fa'afafine had a stronger propensity than Samoan gynephilic men and androphilic women to invest in kin categories that would result in more reliable and substantive increases in indirect fitness (i.e., young, female kin) in hypothetical investment scenarios. In a forced-choice paradigm, although all individuals showed some degree of bias to invest in adaptive kin categories during non-frivolous investment contexts in which the consequences of investment were relatively non-trivial, fa'afafine showed greater adherence to the predicted pattern. In addition, shifting the context from frivolous investments, in which the consequences of investment were relatively trivial, to non-frivolous investments prompted fa'afafine to exhibit an enhanced preference, relative to Samoan gynephilic men and androphilic women, to invest in adaptive kin categories. These findings were consistent with the kin selection hypothesis and suggest that, although all individuals exhibit cognitive biases for increasing indirect fitness, the avuncular cognition of androphilic males has undergone selective enhancement to maximize the accrual of indirect fitness via kin-directed altruism.

Does Geographic Proximity Influence The Expression of Avuncular Tendencies in Canadian Androphilic Males?

AbstractAndrophilia refers to sexual attraction and arousal to adult males, whereas gynephilia refers to sexual attraction and arousal to adult females. The Kin Selection Hypothesis posits that male androphilia may persevere over evolutionary time if the fitness costs of not reproducing directly are offset by increasing one’s inclusive fitness. Theoretically, this could be accomplished by allocating altruism toward close kin, thereby increasing the ability of those kin to reproduce. Evidence for this hypothesis has been garnered from research conducted in Samoa; however, no support has been garnered from research conducted in other, more industrialized cultures (i.e., Canada,usa,uk, Japan). It has been suggested that geographic disconnect from kin might mitigate the potential for androphilic males to exhibit elevated kin-directed altruism in more industrialized cultures. We examined whether Canadian androphilic males expressed elevated willingness to engage in altruistic behavior towards nieces and nephews, compared to gynephilic males and androphilic females, when the activities in question could be executed from a distance. Contrary to our prediction, when comparing groups for willingness to engage in altruistic behavior towards nieces and nephews that could be performed from a distance, we did not find that Canadian androphilic males exhibited significantly higher avuncular (uncle-like) tendencies. Other possible reasons for cross-cultural differences in avuncular tendencies by androphilic males are discussed.

Male Androphilia in the Ancestral Environment

The kin selection hypothesis posits that male androphilia (male sexual attraction to adult males) evolved because androphilic males invest more in kin, thereby enhancing inclusive fitness. Increased kin-directed altruism has been repeatedly documented among a population of transgendered androphilic males, but never among androphilic males in other cultures who adopt gender identities as men. Thus, the kin selection hypothesis may be viable if male androphilia was expressed in the transgendered form in the ancestral past. Using the Standard Cross-Cultural Sample (SCCS), we examined 46 societies in which male androphilia was expressed in the transgendered form (transgendered societies) and 146 comparison societies (non-transgendered societies). We analyzed SCCS variables pertaining to ancestral sociocultural conditions, access to kin, and societal reactions to homosexuality. Our results show that ancestral sociocultural conditions and bilateral and double descent systems were more common in transgendered than in non-transgendered societies. Across the entire sample, descent systems and residence patterns that would presumably facilitate increased access to kin were associated with the presence of ancestral sociocultural conditions. Among transgendered societies, negative societal attitudes toward homosexuality were unlikely. We conclude that the ancestral human sociocultural environment was likely conducive to the expression of the transgendered form of male androphilia. Descent systems, residence patterns, and societal reactions to homosexuality likely facilitated investments in kin by transgendered males. Given that contemporary transgendered male androphiles appear to exhibit elevated kin-directed altruism, these findings further indicate the viability of the kin selection hypothesis.

Separation Anxiety in Feminine Boys: Pathological or Prosocial?

Previous research has found that boys who exhibit Gender Identity Disorder in Children (GIDC) also commonly exhibit elevated traits of childhood separation anxiety. Here, we review recent cross-cultural, nonclinical research that suggests elevated childhood separation anxiety is simply a component of the more general pattern of femininity exhibited by pre-androphilic males (i.e., biological males who are sexually attracted to adult males in adulthood). Whereas clinical perspectives have tended to characterize the co-occurrence of femininity and elevated childhood separation anxiety as psychopathological, we propose an alternate perspective that views this co-occurrence as having a prosocial basis. Specifically, we argue that elevated childhood separation anxiety is a developmental precursor of cognitive biases that evolved to facilitate increased kin-directed altruism in androphilic males. We also detail findings concerning personality and behavioral characteristics of male androphiles that are consistent with this evolutionarily minded perspective. Possible clinical implications that arise from this evolutionarily minded perspective are also discussed.

Kin Selection and the Evolution of Male Androphilia

Iemmola and Camperio Ciani (2008) briefly discussed the kin selection hypothesis for male androphilia, which holds that male androphiles can increase their indirect fitness by providing resources and childcare to close family members, who, in turn, benefit in terms of their direct reproductive success. A basic prediction that flows from this hypothesis is that androphilic males should exhibit increased kin-directed altruism relative to their heterosexual counterparts. Iemmola and Camperio Ciani (2008) stated that ‘‘...various researchers have failed to confirm the kin selection hypothesis. In fact, they found that homosexuals do not contribute in presence or in economic and affective terms more than heterosexuals.’’ In support of this claim, they cited three quantitative studies: one conducted in the U.S. (Bobrow & Bailey, 2001), one conducted in the UK (Rahman & Hull, 2005), and one conducted in Independent Samoa (Vasey, Pocock, & VanderLaan, 2007). It is true that all of these studies failed to find any male sexual orientation differences in money given to kin. It is also true that the studies conducted in the U.S. and the UK failed to find male sexual orientation differences in emotional closeness to kin, while the one conducted in Independent Samoa did not present relevant data bearing on this point. All this being said, Samoan androphilic males do exhibit significantly higher avuncular tendencies compared to gynephilic men (Vasey et al., 2007). This sexual orientation difference in avuncular tendencies was recently replicated by Vasey and VanderLaan (2008) in Independent Samoa using a larger, independent sample, suggesting that it is real and not the result of sampling bias. Vasey and VanderLaan (2008) also demonstrated that androphilic males in Samoa had significantly higher avuncular tendencies even when compared to a more closely matched control group, namely, childless gynephilic men who, like male androphiles, had no direct childcare responsibilities. In addition, Samoan androphilic males exhibited significantly higher avuncular tendencies compared to the materteral (i.e., aunt-like) tendencies of Samoan mothers and childless women (Vasey & VanderLaan, in press). It is notable that some of the avuncular tendency items, for which Samoan androphilic males scored significantly higher compared to men and women, could be characterized as economic in character because they would involve financial output. These items included contributing money for nieces’ and nephews’ medical expenses and buying toys for them. As such, although our Samoan research does not ‘‘confirm’’ the Kin Selection Hypothesis for male androphilia, it is certainly consistent with a basic prediction of that hypothesis, namely, that androphilic male should exhibit distinctly elevated levels of altruistic tendencies toward close kin when compared to other individuals whose life histories are (or will be) characterized by direct reproduction.

Raven scavenging favours group foraging in wolves

Wolves, Canis lupus, routinely live in large packs that include unrelated individuals and mature offspring. Studies show that individual wolves that live in large packs suffer reduced foraging returns. Therefore, group hunting and group living (sociality) in wolves is generally thought to be favoured by indirect fitness gains accrued through kin-directed altruism. However, we show that kin-directed altruism cannot account for groups that include mature offspring or unrelated individuals. We also present an analysis that incorporates a previously ignored feature of wolf foraging ecology, namely the loss of food to scavenging ravens, Corvus corax. By accounting for this process, we show that individuals in large packs do indeed accrue foraging advantages. In the hypothetical absence of this scavenging pressure, an individual would maximize its rate of prey acquisition, and minimize its risk of energetic shortfall, by foraging with just one other individual. However, incorporating the effect of scavenging by ravens leads to a dramatic increase in the predicted group size. Our analysis indicates that per capita gains are highest in the largest observed packs. The greater food-sharing costs in a larger pack are more than offset by smaller losses to scavengers and increased rates of prey acquisition. Thus, in contrast with previous interpretations, the selfish benefits of social foraging appear to contribute to the maintenance of sociality in wolves after all. We explore whether such benefits favour group living in various social carnivores that hunt large prey and are thus vulnerable to scavenging.

Kin recognition and the evolution of altruism.

In 1964, Hamilton formalized the idea of kin selection to explain the evolution of altruistic behaviours. Since then, numerous examples from a diverse array of taxa have shown that seemingly altruistic actions towards close relatives are a common phenomenon. Although many species use kin recognition to direct altruistic behaviours preferentially towards relatives, this important aspect of social biology is less well understood theoretically. I extend Hamilton's classic work by defining the conditions for the evolution of kin-directed altruism when recognizers are permitted to make acceptance (type I) and rejection (type II) errors in the identification of social partners with respect to kinship. The effect of errors in recognition on the evolution of kin-directed altruism depends on whether the population initially consists of unconditional altruists or non-altruists (i.e. alternative forms of non-recognizers). Factors affecting the level of these error rates themselves, their evolution and their long-term stability are discussed.

Kin recognition in rainbowfish ( Melanotaenia eachamensis ): sex, sibs and shoaling

Living with relatives can be beneficial to individuals via the evolution of kin-directed altruism, but this is tempered by the increased risk of inbreeding. Therefore, in social species, the ability to recognise relatives can be highly advantageous. This study focuses on kin discrimination in the Lake Eacham rainbowfish, Melanotaenia eachamensis, an endangered freshwater species from north-east Queensland, Australia. First, I examined kin recognition abilities when a combination of both chemical and visual recognition cues was available. When given a choice of shoaling with same-sex groups, females spent significantly longer with full-sibs rather than half-sibs, full-sibs rather than non-relatives and half-sibs rather than non-relatives. Males spent significantly longer shoaling with full-brothers versus half-brothers, but showed no other shoalmate preferences. Second, in the presence of only chemical cues, females did not discriminate among groups of different levels of relatedness, but males showed a non-significant tendency to associate with full-sibs rather than non-relatives. Male shoaling behaviour seemed to be more influenced by factors other than relatedness, e.g. intra-sexual competition. Finally, I found that the shoaling preferences of females changed when exposed to groups of males. Females preferred to associate with non-relatives rather than half-brothers and non-relatives rather than full-brothers. There was no significant difference in the time spent with half-brothers versus full-brothers. Taken together, my results suggest that females have very good kin recognition abilities. They prefer to shoal with female relatives but avoid male relatives, and so are able to balance the benefits of nepotism and the costs of incest.

Inuit foraging groups: some simple models incorporating conflicts of interest, relatedness, and central-place sharing

Theory and research in evolutionary ecology and sociobiology have developed rather independently of each other. The mutual relevance of these two fields for understanding the adaptive significance of social interactions is exemplified by a consideration of cooperative foraging. Several simple models of optimal foraging group size are developed to explore the effect of the following factors: (1) conflicts of interest between group members and prospective joiners; (2) genealogical relatedness and kin-directed altruism; and (3) the scope of the sharing rule governing division of the harvest. Where the alternative is low-return solitary foraging, “joiners” are shown to prefer group sizes that are often suboptimal (in per capita efficiency) for “members.” Predicted group sizes are also above per-capita optima where kin-directed altruism is important and/or where groups and individuals pool their catch at a central place. The effect of kin-directed altruism is incorporated by defining “inclusive efficiency” measures based on genealogical relatedness and group membership options. Expansion of the harvest-sharing network to include all foragers based at a central place is shown to eliminate conflicts of interest between members and joiners, as well as cancel the role of relatedness in shaping optimal group size or composition. Predictions from the models are tested quantitatively with data on Inuit (Canadian Eskimo) foraging groups. Some models offer an improvement in accounting for variation in Inuit foraging group size, but others do not; empirical and theoretical gaps in our understanding are revealed that call for further research.