Inbreeding avoidance
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Vyhýbání se sexu s příbuznými neboli incestu je považováno za univerzální jev. Jednotlivé obory se však liší vysvětlením vzniku zábrany incestu. Cílem této přehledové studie je představit teorie vyhýbání se incestu z perspektivy kulturní a evoluční antropologie, a přispět tak k pochopení komplexity celé problematiky. Důvodem nízkého výskytu incestu může být existence incestního tabu, představující ustanovené společenské normy a zvyklosti, které incestu zabraňují. Univerzalita incestního tabu se však týká pouze nukleární rodiny, pro širší příbuzenstvo je vysoce kulturně variabilní. Nízký výskyt incestu může být také důsledkem tzv. Westermarckova efektu, při němž dochází ke vzniku sexuální averze mezi jedinci, kteří spolu vyrůstali (tj. obvykle příbuzní jedinci). Empirické studie ukazují, že jedinci, kteří spolu vyrůstali v úzkém kontaktu zhruba do 6 let věku se vzájemně sexuálně nepřitahují. V závěru navrhujeme rozlišovat mezi sexuální indiferencí (tj. absencí přitažlivosti) vůči příbuzným v běžných sociálních interakcích a sexuální averzí, která je specifická pro sexuální kontext.
Avoiding sex with relatives alias incest is considered to be a universal phenomenon. Individual disciplines, however, differ in their explanation of the emergence of incest avoidance. This review aims to introduce the theories of incest avoidance from the point of view of cultural and evolutionary anthropology and thus contribute to the understanding of the complex phenomenon. The reason for the low occurrence of incest might be the existence of the incest taboo – the established social norms and conventions that prevent incest. However, the universality of the incest taboo is limited only to the nuclear family; the incest taboo with respect to wider kin has high cultural variability. The low occurrence of incest might also be a consequence of the so-called Werstermarck effect, i.e., the emergence of sexual aversion among individuals that grew up together (usually relatives), empirical studies show that individuals that grew up together in close contact until approximately six years old are not attracted to each other. Therefore, we conclude that it is important to distinguish between sexual indifference (i.e., the absence of attractivity) towards relatives in daily social interactions and sexual aversion specific to a sexual context.
The current bumblebee decline leads to inbreeding in populations that fosters a loss of allelic diversity and diploid male production. As diploid males are viable and their offspring are sterile, bumblebee populations can quickly fall in a vortex of extinction. In this article, we investigate for the first time a potential premating mechanism through a major chemical reproductive trait (male cephalic labial gland secretions) that could prevent monandrous virgin queens from mating with diploid males. We focus our study on the cephalic labial gland secretions of diploid and haploid males of Bombus terrestris (L.). Contrary to initial expectations, our results do not show any significant differentiation of cephalic labial gland secretions between diploid and haploid specimens. Queens seem therefore to be unable to avoid mating with diploid males based on their compositions of cephalic labial gland secretions. This suggests that the vortex of extinction of diploid males could not be stopped through premating avoidance based on the cephalic labial gland secretions but other mechanisms could avoid mating between diploid males and queens.
- MeSH
- inbreeding MeSH
- pachové žlázy sekrece MeSH
- ploidie * MeSH
- sexuální chování zvířat fyziologie MeSH
- sexuální lákadla chemie MeSH
- včely genetika metabolismus MeSH
- zachování přírodních zdrojů MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
Extremely high variability in genes of the major histocompatibility complex (MHC) in vertebrates is assumed to be a consequence of frequency-dependent parasite-driven selection and mate preferences based on promotion of offspring heterozygosity at MHC, or potentially, genome-wide inbreeding avoidance. Where effects have been found, mate choice studies on rodents and other species usually find preference for MHC-dissimilarity in potential partners. Here we critically review studies on MHC-associated mate choice in humans. These are based on three broadly different aspects: (1) odor preferences, (2) facial preferences and (3) actual mate choice surveys. As in animal studies, most odor-based studies demonstrate disassortative preferences, although there is variation in the strength and nature of the effects. In contrast, facial attractiveness research indicates a preference for MHC-similar individuals. Results concerning MHC in actual couples show a bias towards similarity in one study, dissimilarity in two studies and random distribution in several other studies. These vary greatly in sample size and heterogeneity of the sample population, both of which may significantly bias the results. This pattern of mixed results across studies may reflect context-dependent and/or life history sensitive preference expression, in addition to higher level effects arising out of population differences in genetic heterogeneity or cultural and ethnic restrictions on random mating patterns. Factors of special relevance in terms of individual preferences are reproductive status and long- vs. short-term mating context. We discuss the idea that olfactory and visual channels may work in a complementary way (i.e. odor preference for MHC-dissimilarity and visual preference for MHC-similarity) to achieve an optimal level of genetic variability, methodological issues and interesting avenues for further research.
As previously suggested, preferences for kin body odor might undergo an adaptive change over the course of puberty in order to avoid potential inbreeding, resulting in aversion to body odor of the opposite-gender kin as individuals mature sexually. However, studies based on mutual body odor aversion are rather inconclusive. We therefore investigated whether children's reports of individuals smelling good or bad differed as a function of age and pubertal status. We asked 219 children (94 male) aged 10 to 15 years to assess their pubertal development using a standardized measure and to name individuals they thought smelled good or bad. Results of the present study show that the older the girls were, the more likely they were to name males than females among nice-smelling people. Further, in both girls and boys alike, children with higher puberty scores were more likely to name children than adults. Neither in girls nor in boys did we observe any concurrent effect of age or pubertal status on children's reports of persons thought to smell bad. Irrespective of whether these changes are driven by age itself or age-related phenomena, these results suggest a shift toward a more general positive attitude to peers rather than active kin avoidance.
- MeSH
- čichová percepce * MeSH
- dítě MeSH
- lidé MeSH
- mladiství MeSH
- odoranty * MeSH
- pohlavní dospělost * MeSH
- stárnutí psychologie MeSH
- tělesná konstituce MeSH
- Check Tag
- dítě MeSH
- lidé MeSH
- mladiství MeSH
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- Publikační typ
- časopisecké články MeSH
Self-resemblance has been found to have a context-dependent effect when expressing preferences for faces. Whereas dissimilarity preference during mate choice in animals is often explained as an evolutionary adaptation to increase heterozygosity of offspring, self-resemblance can be also favored in humans, reflecting, e.g., preference for kinship cues. We performed two studies, using transformations of facial photographs to manipulate levels of resemblance with the rater, to examine the influence of self-resemblance in single vs. coupled individuals. Raters assessed facial attractiveness of other-sex and same-sex photographs according to both short-term and long-term relationship contexts. We found a preference for dissimilarity of other-sex and same-sex faces in single individuals, but no effect of self-resemblance in coupled raters. No effect of sex of participant or short-term vs. long-term attractiveness rating was observed. The results support the evolutionary interpretation that dissimilarity of other-sex faces is preferred by uncoupled individuals as an adaptive mechanism to avoid inbreeding. In contrast, lower dissimilarity preference of other-sex faces in coupled individuals may reflect suppressed attention to attractiveness cues in potential alternative partners as a relationship maintenance mechanism, and its substitution by attention to cues of kinship and psychological similarity connected with greater likelihood of prosocial behavior acquisition from such persons.
- Publikační typ
- časopisecké články MeSH
