Kin selection and male androphilia in Samoan fa'afafine

The Kin Selection Hypothesis for male androphilia posits that genes for male androphilia can be maintained in the population if the fitness costs of not reproducing directly are offset by enhancing inclusive fitness. In theory, androphilic males can increase their inclusive fitness by directing altruistic behavior toward kin, which, in turn, allows kin to increase their reproductive success. Previous research conducted in Western countries has failed to find any support for this hypothesis. The current study tests this basic prediction of the Kin Selection Hypothesis for male androphilia by comparing the altruistic tendencies of androphilic and gynephilic males in the Polynesian nation of Independent Samoa. In Independent Samoa, androphilic males are known locally as fa'afafine. Altruistic tendencies were assessed using a Kin Selection Questionnaire. Comparisons of the altruistic tendencies of fa'afafine and gynephilic men revealed that these two groups did not differ in terms of their overall generosity and allocation of financial resources toward kin, nor did they differ in terms of general neediness or financial resources obtained from kin. Fa'afafine did, however, report greater avuncular tendencies than gynephilic men. Although the greater avuncular tendencies of fa'afafine support the basic prediction of the Kin Selection Hypothesis for male androphilia, further research is needed before one can conclude that these elevated tendencies represent a specially designed adaptation for promoting the fitness of kin. We discuss a number of sociocultural factors that might promote the expression of avuncular tendencies by androphilic males in Independent Samoa. Our results underscore the importance of testing functional hypotheses in evolutionarily appropriate environments.     

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.     

Materteral and Avuncular Tendencies in Samoa

Androphilia refers to sexual attraction and arousal to adult males, whereas gynephilia refers to sexual attraction and arousal to adult females. In Independent Samoa, androphilic males, most of whom are effeminate or transgendered, are referred to as fa’afafine, which means “in the manner of a woman.” Previous research has established that fa’afafine report significantly higher avuncular tendencies relative to gynephilic men. We hypothesized that Samoan fa’afafine might adopt feminine gender role orientations with respect to childcare activity. If so, then the fa’afafine’s femininity might be a proximate mechanism for promoting their elevated avuncular tendencies. Our analyses indicated that fa’afafine had significantly higher willingness to assist in the childcare of nieces and nephews than childless women, mothers, or men, none of whom differed from each other on this measure. Thus, femininity does not appear to explain the fa’afafine’s pattern of avuncular tendencies, nor the women’s pattern of materteral (i.e., aunt-like) tendencies, relative to gynephilic men. We discuss how the fa’afafine “third” gender status might influence the expression of their elevated avuncular tendencies.

Viewing Time Measures of Sexual Orientation in Samoan Cisgender Men Who Engage in Sexual Interactions with Fa’afafine

Androphilia refers to attraction to adult males, whereas gynephilia refers to attraction to adult females. The current study employed self-report and viewing time (response time latency) measures of sexual attraction to determine the sexual orientation of Samoan cisgender men (i.e., males whose gender presentation and identity is concordant with their biological sex) who engage in sexual interactions with transgender male androphiles (known locally as fa’afafine) compared to: (1) Samoan cisgender men who only engage in sexual interactions with women, and (2) fa’afafine. As expected, both measures indicated that cisgender men who only engaged in sexual interactions with women exhibited a gynephilic pattern of sexual attraction, whereas fa’afafine exhibited an androphilic one. In contrast, both measures indicated that cisgender men who engaged in sexual interactions with fa’afafine demonstrated a bisexual pattern of sexual attraction. Most of the cisgender men who exhibited bisexual viewing times did not engage in sexual activity with both men and women indicating that the manner in which bisexual patterns of sexual attraction manifest behaviorally vary from one culture to the next.     

Offspring production among the extended relatives of Samoan men and fa'afafine

Androphilia refers to sexual attraction to adult males, whereas gynephilia refers to sexual attraction to adult females. Male androphilia is an evolutionary paradox. Its development is at least partially influenced by genetic factors, yet male androphiles exhibit lower reproductive output, thus raising the question of how genetic factors underlying its development persist. The sexual antagonism hypothesis posits that the fitness costs associated with genetic factors underlying male androphilia are offset because these same factors lead to elevated reproduction on the part of the female relatives of androphilic males. Western samples drawn from low fertility populations have yielded inconsistent results when testing this hypothesis. Some studies documented elevated reproduction among the matrilineal female kin of androphilic males, whereas others found such effects in the paternal line. Samoa is a high-fertility population in which individuals reproduce closer to their maximum capacities. This study compared the reproductive output of the paternal and maternal line grandmothers, aunts, and uncles of 86 Samoan androphilic males, known locally as fa'afafine, and 86 Samoan gynephilic males. Reproductive output was elevated in the paternal and maternal line grandmothers, but not aunts or uncles, of fa'afafine. These findings are consistent with the sexual antagonism hypothesis and suggest that male androphilia is associated with elevated reproduction among extended relatives in both the maternal and paternal line. Discussion focuses on how this study, in conjunction with the broader literature, informs various models for the evolution of male androphilia via elevated reproduction on the part of female kin.     

The Relationship between Adult Occupational Preferences and Childhood Gender Nonconformity among Samoan Women,Men, and <Emphasis Type="Italic">Fa</Emphasis>’<Emphasis Type="Italic">afafine</Emphasis>

Previous research has found that sex differences in occupational preferences are both substantial and cross-culturally universal. Androphilic males tend to display “gender-shifted” occupational preferences, with relatively female-typical interests. Past research has overwhelmingly relied on Western samples; this article offers new insights from a non-Western setting. Known locally as fa’afafine, androphilic males in Samoa occupy a third-gender category. Data were collected in Samoa from 103 men, 103 women, and 103 fa’afafine regarding occupational preferences and recalled childhood gender nonconformity (CGN). A substantial sex difference was observed in the occupational preferences of men and women (d = 2.04). Interestingly, women and fa’afafine did not differ in their preferences (p = 0.89), indicating a complete gender inversion of occupational preferences in the latter. Although there was no correlation between women’s CGN and masculine occupational preferences, there was a significant correlation (r = ?0.62) between these variables in both men and fa’afafine. Among males (both men and fa’afafine), increased CGN was associated with preference for feminine occupations. The present research corroborates past findings and furnishes support for the conclusion that female-typical occupational preferences are a cross-culturally invariant aspect of male androphilia.     

Testing kin altruism in long-tailed macaques (Macaca fascicularis) in a food-sharing experiment

Social grooming and coalition formation have been main foci in studies concerning altruism in monkeys. Results have been inconclusive because the altruistic nature of these behaviors remains unclear. I investigated altruism in a more transparent context via an apparatus in which captive long-tailed macaque females had the choice to exploit a food source themselves or to yield the food to a test partner. I hypothesized that if potential donors behaved altruistically toward kin, they would yield the food sources longer to kin than to nonkin. Of 11 tested potential donors, 8 did not discriminate between daughters or sisters and nonkin. Thus, the experiments do not support the kin altruism hypothesis. Three females let their youngest offspring have more food than matched juvenile nonrelatives. Behavioral observations strongly suggested,however, that it was primarily spiteful behavior toward juvenile nonrelatives that caused the differences between kin and nonkin in these three cases.     

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.     

Helping in cooperatively breeding long-tailed tits: a test of Hamilton's rule

Inclusive fitness theory provides the conceptual framework for our current understanding of social evolution, and empirical studies suggest that kin selection is a critical process in the evolution of animal sociality. A key prediction of inclusive fitness theory is that altruistic behaviour evolves when the costs incurred by an altruist (c) are outweighed by the benefit to the recipient (b), weighted by the relatedness of altruist to recipient (r), i.e. Hamilton''s rule rb > c. Despite its central importance in social evolution theory, there have been relatively few empirical tests of Hamilton''s rule, and hardly any among cooperatively breeding vertebrates, leading some authors to question its utility. Here, we use data from a long-term study of cooperatively breeding long-tailed tits Aegithalos caudatus to examine whether helping behaviour satisfies Hamilton''s condition for the evolution of altruism. We show that helpers are altruistic because they incur survival costs through the provision of alloparental care for offspring. However, they also accrue substantial benefits through increased survival of related breeders and offspring, and despite the low average relatedness of helpers to recipients, these benefits of helping outweigh the costs incurred. We conclude that Hamilton''s rule for the evolution of altruistic helping behaviour is satisfied in this species.     

Lineage, Sex, and Wealth as Moderators of Kin Investment

Supporting Hamilton’s inclusive fitness theory, archival analyses of inheritance patterns in wills have revealed that people invest more of their estates in kin of closer genetic relatedness. Recent classroom experiments have shown that this genetic relatedness effect is stronger for relatives of direct lineage (children, grandchildren) than for relatives of collateral lineage (siblings, nieces, nephews). In the present research, multilevel modeling of more than 1,000 British Columbian wills revealed a positive effect of genetic relatedness on proportions of estates allocated to relatives. This effect was qualified by an interaction with lineage, such that it was stronger for direct than for collateral relatives. Exploratory analyses of the moderating role of benefactors’ sex and estate values showed the genetic relatedness effect was stronger among female and wealthier benefactors. The importance of these moderators to understanding kin investment in modern humans is discussed.     

Childlessness predicts helping of nieces and nephews in United States, 1910

The 'helpers at the nest' hypothesis suggests that individuals who are not currently reproducing often help kin by caretaking and thereby increase their inclusive fitness. Using a large scale historical dataset (Integrated Public Use Microdata Series sample of 1910; n=13,935), the hypothesis is tested that childless couples are more likely to fulfil such a role by taking care of a niece or nephew, but not a parent, than couples with children. Childless couples were significantly more likely to take care of a niece or nephew than couples with children. In contrast, couples with children and childless couples did not differ in caretaking of parents. Childless couples were also more likely to have more and younger nieces/nephews in their home than couples with children.     

Kin Relationships and the Caregiving Biases of Grandparents, Aunts, and Uncles

Paternity certainty and matrilineal family ties have been used to explain the asymmetric caregiving of grandparents and aunts and uncles. The proximate mechanisms underlying biased kin investment, however, remain unclear. A central question of the study presented here was whether the parent-kin relationship is an important link in the caregiving. In a two-generational questionnaire study, we asked subjects to estimate the intensity of their relationships to parents, grandparents, aunts, and uncles (emotional closeness, investment received in childhood). In addition, the subjects’ parents rated their emotional closeness to their parents and siblings. We found that the parent-kin relationship was closely linked to the relatives’ child care and could partly explain asymmetric caregiving. Maternal aunts played a special role as caregivers. Especially the mother’s younger or last-born sister cared intensively for nieces and nephews, regardless of her closeness to the subjects’ mother.     

Journeys of patronage: moral economies of transactional sex,kinship, and female migration from Mozambique to Europe

The article explores how young Mozambican women's migratory trajectories towards Europe are shaped by sexual relationships with older white men and obligations towards female kin. Triads of exchange between young women known as curtidoras (women enjoying life) and their partners and kin in Maputo are understood through theories of patronage and exchange moralities. Searching for respect, adventure, and consumption in the sexual economy, young women at the same time struggle to ensure their families' well‐being by redistributing the money they extract from white men. Sexual‐monetary transactions, love, and desire must be understood as part of broader moralities of exchange in which migration to Europe and sending of remittances is also a kinship project. The forms of patronage available in Maputo's sexual economy become stepping stones as well as obstacles to migration northwards.     

Do post-menopausal women provide more care to their kin?: evidence of grandparental caregiving from two large-scale national surveys

Drawing on the logical principles of life-history theory, it may be hypothesized that—compared to pre-menopausal women—post-menopausal women will spend more time caring for grandchildren and other kin. This hypothesis was tested in two studies, on results obtained from two large datasets documenting altruistic behaviors of pre-menopausal and post-menopausal women in the United States (n = 7161) and Australia (N = 25,066). Results from both studies revealed that (even when controlling statistically for age, health, financial resources, and other pertinent variables), post-menopausal women devoted more time to grandparental caregiving. This effect was specific to kin care: Menopause status was not as strongly related to a measure of non-kin-directed altruistic behavior (time spent volunteering). These results provide the first empirical support for a previously-untested behavioral implication of menopause.     

Effects of Lactobacillus paracasei CNCM I-4034, Bifidobacterium breve CNCM I-4035 and Lactobacillus rhamnosus CNCM I-4036 on Hepatic Steatosis in Zucker Rats

We have previously described the safety and immunomodulatory effects of Lactobacillus paracasei CNCM I-4034, Bifidobacterium breve CNCM I-4035 and Lactobacillus rhamnosus CNCM I-4036 in healthy volunteers. The scope of this work was to evaluate the effects of these probiotic strains on the hepatic steatosis of obese rats. We used the Zucker rat as a genetic model of obesity. Zucker-Lepr^fa/fa rats received one of three probiotic strains, a mixture of L. paracasei CNCM I-4034 and B. breve CNCM I-4035, or a placebo for 30 days. An additional group of Zucker-lean^+/fa rats received a placebo for 30 days. No alterations in intestinal histology, in the epithelial, lamina propria, muscular layers of the ileal or colonic mucosa, or the submucosae, were observed in any of the experimental groups. Triacylglycerol content decreased in the liver of Zucker-Lepr^fa/fa rats that were fed L. rhamnosus, B. breve, or the mixture of B. breve and L. paracasei. Likewise, the area corresponding to neutral lipids was significantly smaller in the liver of all four groups of Zucker-Lepr^fa/fa rats that received probiotics than in rats fed the placebo. Zucker-Lepr^fa/fa rats exhibited significantly greater serum LPS levels than Zucker-lean^+/fa rats upon administration of placebo for 30 days. In contrast, all four groups of obese Zucker-Lepr^fa/fa rats that received LAB strains exhibited serum LPS concentrations similar to those of Zucker-lean^+/fa rats. Serum TNF-α levels decreased in the Zucker-Lepr^fa/fa rats that received B. breve, L. rhamnosus, or the mixture, whereas L. paracasei feeding decreased IL-6 levels in the serum of Zucker-Lepr^fa/fa rats. In conclusion, the probiotic strains reduced hepatic steatosis in part by lowering serum LPS, and had an anti-inflammatory effect in obese Zucker rats.     

Suppression of the facet-strawberry position effect in Drosophila by lesions adjacent to notch

The recessive visible rough eye mutant effect of fa ^swb, a small deletion at the 5' end of the Notch locus, is suppressed when fa^swb is coupled to five different closely linked deficiencies distal to salivary band 3C7. In addition, an inversion with a proximal breakpoint between 3C3 and 3C5 similarly suppresses the mutant effect. The data support the position effect interpretation of fa ^swb: The small deletion allows functions distal to Notch to interfere with functions at Notch, and when the interference is eliminated, the fa^swb-mutant effect disappears.—The fa^swb deletion also interacts with another recessive visible rough-eye mutant at Notch called fa^g. In the cis condition, fa^swb fa ^g double mutants have a mutant-eye phenotype like fa ^g (similar to the mutant effect of fa^swb) and, in addition, express an accessory phenotype (thickened wing veins). Although the mutant-eye effect of fa^swb can be suppressed by lesions adjacent to Notch, the accessory phenotype of the coupled mutants is not suppressed. It is suggested that the fa^swb deletion has two observable effects: One is a modifiable position effect causing the fa^swb rough-eye phenotype; the other is a stable effect exerted upon a 5-kb insertion that is the probable cause of the fa^g mutant expression, thus resulting in a wing effect that accompanies the eye effect of fa ^g.     

Improving the Quality of Adult Mortality Data Collected in Demographic Surveys: Validation Study of a New Siblings' Survival Questionnaire in Niakhar,Senegal

Background

In countries with limited vital registration, adult mortality is frequently estimated using siblings'' survival histories (SSHs) collected during Demographic and Health Surveys (DHS). These data are affected by reporting errors. We developed a new SSH questionnaire, the siblings'' survival calendar (SSC). It incorporates supplementary interviewing techniques to limit omissions of siblings and uses an event history calendar to improve reports of dates and ages. We hypothesized that the SSC would improve the quality of adult mortality data.

Methods and Findings

We conducted a retrospective validation study among the population of the Niakhar Health and Demographic Surveillance System in Senegal. We randomly assigned men and women aged 15–59 y to an interview with either the DHS questionnaire or the SSC. We compared SSHs collected in each group to prospective data on adult mortality collected in Niakhar. The SSC reduced respondents'' tendency to round reports of dates and ages to the nearest multiple of five or ten (“heaping”). The SSC also had higher sensitivity in recording adult female deaths: among respondents whose sister(s) had died at an adult age in the past 15 y, 89.6% reported an adult female death during SSC interviews versus 75.6% in DHS interviews (p = 0.027). The specificity of the SSC was similar to that of the DHS questionnaire, i.e., it did not increase the number of false reports of deaths. However, the SSC did not improve the reporting of adult deaths among the brothers of respondents. Study limitations include sample selectivity, limited external validity, and multiple testing.

Conclusions

The SSC has the potential to collect more accurate SSHs than the questionnaire used in DHS. Further research is needed to assess the effects of the SSC on estimates of adult mortality rates. Additional validation studies should be conducted in different social and epidemiological settings.

Trial Registration

Controlled-Trials.com ISRCTN06849961 Please see later in the article for the Editors'' Summary     

Enhancement and Suppression of a Euchromatic Position Effect at NOTCH in Drosophila

The recessive visible rough-eye mutant facet-strawberry, fa^swb, is caused by the deletion of 0.8 kb of base sequences from the 5' end of the Notch locus. Visible deficiencies adjacent to fa^swb suppress this mutant effect of the Notch locus, and in the same region (between salivary bands 3C1 and 3C7), we have demonstrated the presence of at least one partial suppressor and one enhancer of the fa^swb position effect at Notch.—The enhancer seems to be a small inversion approximately equal to the salivary-band doublet 3C2, 3, and the partial suppressor lies between the inversion in 3C2, 3 and the small deletion in fa^swb immediately distal to 3C7. Neither the enhancer, e(fa^swb), nor the partial suppressor, su(fa^swb), can be detected except when linked in cis to fa^swb. The e(fa^swb) and the su(fa^swb), in unison, act antagonistically on the fa^swb position effect.—The fa^swb mutant is interpreted to be a nonvariegating position effect at the Notch locus resulting from a novel euchromatic—euchromatic association of base sequences caused by the small deletion.     

Molecular characterization of argininosuccinate synthase and argininosuccinate lyase from the liver of the African lungfish Protopterus annectens,and their mRNA expression levels in the liver,kidney, brain and skeletal muscle during aestivation

Argininosuccinate synthase (Ass) and argininosuccinate lyase (Asl) are involved in arginine synthesis for various purposes. The complete cDNA coding sequences of ass and asl from the liver of Protopterus annectens consisted of 1,296 and 1,398 bp, respectively. Phylogenetic analyses revealed that the deduced Ass and Asl of P. annectens had close relationship with that of the cartilaginous fish Callorhinchus milii. Besides being strongly expressed in the liver, ass and asl expression were detectable in many tissues/organs. In the liver, mRNA expression levels of ass and asl increased significantly during the induction phase of aestivation, probably to increase arginine production to support increased urea synthesis. The increases in ass and asl mRNA expression levels during the prolonged maintenance phase and early arousal phase of aestivation could reflect increased demand on arginine for nitric oxide (NO) production in the liver. In the kidney, there was a significant decrease in ass mRNA expression level after 6 months of aestivation, indicating possible decreases in the synthesis and supply of arginine to other tissues/organs. In the brain, changes in ass and asl mRNA expression levels during the three phases of aestivation could be related to the supply of arginine for NO synthesis in response to conditions that resemble ischaemia and ischaemia–reperfusion during the maintenance and arousal phase of aestivation, respectively. The decrease in ass mRNA expression level, accompanied with decreases in the concentrations of arginine and NO, in the skeletal muscle of aestivating P. annectens might ameliorate the potential of disuse muscle atrophy.     

Kin selection,kin avoidance and correlated strategies

Summary Kin selection of correlated strategies is examined for both weak and strong altruism under simple haploid inheritance. While kin assortment enhances the range of evolutionary stability for (strongly altruistic) correlated strategies (defined herein), kin avoidance is possible under a weakly altruistic correlated strategy. When social competition induces role assignments of variable fitness, group mates may prefer association with non-relatives. Even when group life is mandatory, an individual may accept the risk of abandonment (and reproductive death) rather then associate with kin: a competitive superior may behave altruistically by permitting competitively inferior kin to emigrate. Thus, kin selection and social competition are not necessarily mutually supportive processes within groups. I conclude by interpreting dominance as a strongly altruistic correlated strategy in two social hymenopteran contexts.