Geänderte Inhalte

Understanding how human mating psychology is affected by changes in female cyclic fertility is informative for comprehending the evolution of human reproductive behavior. Based on differential selection pressures between the sexes, men are assumed to have evolved adaptations to notice women's within-cycle cues to fertility and show corresponding mate retention tactics to secure access to their female partners when fertile. However, previous studies suffered from methodological shortcomings and yielded inconsistent results. In a large, preregistered online dyadic diary study (384 heterosexual couples), we found no compelling evidence that men notice women's fertility status (as potentially reflected in women's attractiveness, sexual desire, or wish for contact with others) or display mid-cycle increases in mate retention tactics (jealousy, attention, wish for contact or sexual desire towards female partners). These results extend our current understanding of the evolution of women's concealed ovulation and oestrus, and suggest that both might have evolved independently.

Background: In the general population, 10.6 % of people favor their left hand over the right for motor tasks. Previous research suggests higher prevalence of atypical (left-, mixed-, or non-right-) handedness in (i) twins compared to singletons, and in (ii) monozygotic compared to dizygotic twins. Moreover, (iii) studies have shown a higher rate of handedness concordance in monozygotic compared to dizygotic twins, in line with genetic factors playing a role for handedness. Methods: We identified 59 studies from previous literature and performed three sets of random effects meta-analyses on (i) twin-to-singleton Odds Ratios (21 studies, n = 189,422 individuals), (ii) monozygotic-to-dizygotic twin Odds Ratios (48 studies, n = 63,295 individuals), and (iii) concordance Odds Ratios (44 studies, n = 36,217 twin pairs). We also tested for potential effects of moderating variables such as sex, age, the method used to assess handedness and the twins’ zygosity. Results: We found (i) evidence for higher prevalence of left- (Odds Ratio = 1.40) and non-right- (Odds Ratio = 1.36), but not mixed-handedness (Odds Ratio = 1.08) among twins compared to singletons. We further showed a reduction of difference over time, which suggests that higher levels of left-handedness observed in twins are linked to a higher frequency of birth complications which might have dropped nowadays in their overall prevalence because of better healthcare. While there was (ii) no difference between monozygotic and dizygotic twins regarding prevalence of left- (Odds Ratio = 0.98), mixed- (Odds Ratio = 0.96), or non-right-handedness (Odds Ratio = 1.01), we found that (iii) handedness concordance was elevated among monozygotic compared to dizygotic twin pairs (Odds Ratio = 1.11). Moderator analyses showed our results to be robust against potentially confounding variables. Conclusion : We provide the largest and most comprehensive meta-analysis on handedness in twins. Results suggest that the previously reported effect that twins are more likely to be left-handed than singletons is robust. Furthermore, we also provide robust evidence that monozygotic twins are more likely to be concordant for handedness than dizygotic twins. In line with recent genome-wide association studies, this finding supports a partially genetic determination of handedness.

The heritability of handedness, the most commonly investigated lateralised phenotype, has been consistently estimated to be ~25%. Handedness is linked to brain asymmetries such as hemispheric dominance for language and it has been associated to psychiatric and neurodevelopmental disorders. Here, we investigated the genetics of handedness as well as foot and eye preference and their relationship with neurodevelopmental phenotypes. Parental left-side preference increased the chance of an individual to be left-sided for the same trait, with stronger maternal than paternal effects ( n  ≤ 4,042 family trios from the Avon Longitudinal Study of Parents and Children (ALSPAC)). By regressing out effects of sex, age, and the first two ancestry-informative principal components, we transformed categorical phenotypes (right, mixed, left) into quantitative measures for single nucleotide polymorphism (SNP) based heritability (SNP-h 2 ). We found moderate SNP-h 2  for transformed measures of hand (.21) and foot (.28) but negligible SNP-h 2  for eye preference (.02) or the untransformed categorical measures ( n  ≤ 5,931). Genomic and behavioural structural equation modelling (SEM) in ALSPAC and a twin cohort from Hong Kong ( n  = 366) identified a shared genetic factor contributing to hand, foot, and eye preference, but no independent effects on individual phenotypes. Higher polygenic risk scores (PRS) for ADHD and genetic predisposition towards lower IQ and educational attainment (EA) were associated with left hand preference. This finding supports the idea of a right-handedness advantage on neurodevelopmental outcomes. This is the largest study conducted to date for multiple lateralised measures in the same individuals. Our analysis demonstrates how quantitative multidimensional laterality phenotypes are better suited to capture the underlying genetic component than simple left/right binary traits.

Sarah hat an der Georg-August-Universität Göttingen ihren Bachelor 2014 in allgemeiner Sprachwissenschaft und der Anglistik abgeschlossen. Für ihre Bachelorarbeit, die sie bereits in der WortSchatzInsel erarbeitete, befasste sie sich mit orthographischer Aktivierung während der auditiven Sprachverarbeitung bei Erwachsenen. Anschließend führte es sie für den Master 2014/2015 zum University College London, wo sie sich mit dem Erwerb von Pragmatik, und skalaren Implikaturen im Besonderen, beschäftigte. Seit Oktober 2015 ist Sarah nun Doktorandin in der Forschungsgruppe Psychologie der Sprache. In ihrer Arbeit untersucht sie bereichsübergreifende Einflüsse von Wörtern und Handlungen auf den frühkindlichen Spracherwerb, also wie bestimmte Bewegungen den Spracherwerb des Kindes beeinflussen können. Dieses Projekt ist im Rahmen der DFG-geförderten Forschergruppe ‚‚Crossing the borders: The interplay of language, cognition, and the brain in early human development‘‘ und wird in Zusammenarbeit mit der Uni Potsdam durchgeführt. Des Weiteren interessiert Sarah sich dafür, wie die prosoziale Entwicklung des Kindes, Kontext und linguistische Strukturen Auswirkungen haben auf den Erwerb von semantischen und pragmatischen Elementen. Zudem ist Sarah ein Associate der Research Training Group 2070 zum Thema ‚‚Verstehen sozialer Beziehungen‘‘ und Teil des Promotionsprogramms ‚‚Behaviour and Cognition‘‘. Hier geht es weiter zur Seite der Forschergruppe: https://crossing-project.de Und hier geht es weiter zu ihrer privaten Website: http://www.sarah-eiteljoerge.de Und ihrer researchgate Seite: https://www.researchgate.net/profile/Sarah_Eiteljoerge2