Menschenbildkonflikte: Evolutionstheorie und Naturalismus

The view that humans comprise only two types of beings, women and men, a framework that is sometimes referred to as the "gender binary," played a profound role in shaping the history of psychological science. In recent years, serious challenges to the gender binary have arisen from both academic research and social activism. This review describes 5 sets of empirical findings, spanning multiple disciplines, that fundamentally undermine the gender binary. These sources of evidence include neuroscience findings that refute sexual dimorphism of the human brain; behavioral neuroendocrinology findings that challenge the notion of genetically fixed, nonoverlapping, sexually dimorphic hormonal systems; psychological findings that highlight the similarities between men and women; psychological research on transgender and nonbinary individuals' identities and experiences; and developmental research suggesting that the tendency to view gender/sex as a meaningful, binary category is culturally determined and malleable. Costs associated with reliance on the gender binary and recommendations for future research, as well as clinical practice, are outlined. (PsycINFO Database Record (c) 2019 APA, all rights reserved).

Whereas a categorical difference in the genitals has always been acknowledged, the question of how far these categories extend into human biology is still not resolved. Documented sex/gender differences in the brain are often taken as support of a sexually dimorphic view of human brains ("female brain" or "male brain"). However, such a distinction would be possible only if sex/gender differences in brain features were highly dimorphic (i.e., little overlap between the forms of these features in males and females) and internally consistent (i.e., a brain has only "male" or only "female" features). Here, analysis of MRIs of more than 1,400 human brains from four datasets reveals extensive overlap between the distributions of females and males for all gray matter, white matter, and connections assessed. Moreover, analyses of internal consistency reveal that brains with features that are consistently at one end of the "maleness-femaleness" continuum are rare. Rather, most brains are comprised of unique "mosaics" of features, some more common in females compared with males, some more common in males compared with females, and some common in both females and males. Our findings are robust across sample, age, type of MRI, and method of analysis. These findings are corroborated by a similar analysis of personality traits, attitudes, interests, and behaviors of more than 5,500 individuals, which reveals that internal consistency is extremely rare. Our study demonstrates that, although there are sex/gender differences in the brain, human brains do not belong to one of two distinct categories: male brain/female brain.

Largely based on pre-theory that ties high testosterone (T) to masculinity, and low T to femininity, high T is mainly studied in relation to aggression, mating, sexuality, and challenge, and low T with parenting. Evidence, however, fails to support this, and the social variability in T is better accounted for by a competition-nurturance trade-off as per the Steroid/Peptide Theory of Social Bonds (van Anders et al., 2011). Four key domains are discussed: adult-infant interactions, sexual desire, sexual behavior, and partnering. Empirical engagements with gender/sex are shown to lead to important insights over assumptions about masculinity-femininity. Humans are discussed within a comparative framework that attends to cross-species principles informed by human insights alongside human-specific particularities like social constructions, which are critical to evolutionary understandings of the social role of T. This paper thus integrates seemingly orthogonal perspectives to allow for transformative approaches to an empirically-supported social phenomenology of T. Copyright © 2013 Elsevier Inc. All rights reserved.