Die ideologische Weigerung, evolutionär entstandene Geschlechtsunterschiede anzuerkennen

Ein interessanter Artikel von David Gary, der hier bereits häufiger besprochen worden ist. Er bespricht einen Artikel, in dem es darum geht, dass es keinen Mutterinstinkt gibt und auch sonst keine biologischen Geschlechterunterschiede bestehen:

Conaboy’s goal, apparently, is to undo 200 million years of mammalian evolution, which produced maternal investment in offspring. She correctly points out that, in the past, Western societies discouraged and often excluded women from entering higher education and professional jobs. But while this continues to occur in many parts of the world, in highly developed Western societies women now outnumber men in higher education. Jerry Coyne has provided a valuable rejoinder on this point and several others in Conaboy’s essay, to which I will add a few more here.

Es ist ein alter Grundsatz, dass sie Verbesserungen nicht wahrnehmen, sofern sie nicht zur Opferrolle passen. Es wird nie sein „Frauenanteil stark gestiegen“, sondern immer eher ein negativer Spin: Frauen wurden früher unterdrückt, deswegen besteht die Unterdrückung fort, selbst wenn Frauen heute häufiger studieren als Männer.

The first relates to the construction of the parental brain, about which Conaboy writes:

New research on the parental brain makes clear that the idea of maternal instinct as something innate, automatic and distinctly female is a myth, one that has stuck despite the best efforts of feminists to debunk it from the moment it entered public discourse.

According to this view, the parental brain is essentially a blank slate filled with experiences chiefly dictated by social expectations for women and men. In other words, women’s and men’s parental brains and associated behaviors would be the same with the right social mores and behavioral expectations. But this claim fails to consider that males do very little parenting in the vast majority of mammals, especially those (including humans) in which males compete intensely for status.

Bei einem Säugetier mit einer hohen Betreuungszeit des Kindes wäre es in der Tat überraschend, wenn bei den Weibchen keine besondere Spezialisierung in Bezug auf Kinder vorliegen würde. Und sei es einfach der Umstand, dass Frauen eher solche Aufgaben übernehmen wollen und Männer eher versuchen Status aufzubauen. Das muss nicht bedeuten, dass alle Frauen oder alle Männer das so sehen oder Männer nicht in der Lage sind diese Aufgaben zu übernehmen, aber es wäre verwunderlich, wenn nicht zumindest im Schnitt Frauen diese Arbeit eher übernehmen wollten. Immerhin war es lange so, dass nur die Frau stillen konnte und damit das Baby versorgen konnte und wenn sie das nicht gemacht hat oder sie das nicht interessiert hat, dann konnte dies erhebliche Nachteile für die Weitergabe der Gene haben.

As it happens, humans are among the exceptions to this pattern. Men invest considerably more in their children than do the males of our closest relatives—chimpanzees and bonobos—who are uniformly deadbeats. Nevertheless, the sex difference in the direct care of human children is found throughout the world, especially in infancy. Fathers among the Aka—a nomadic people indigenous to the Democratic Republic of the Congo—provide more direct care to their infants and children than fathers in any other society hitherto studied. Yet Barry Hewlett’s observations indicate that when in camp, “the father would on average hold his infant for a total of 57 minutes while the mother would hold the infant [for] 490 minutes.”

Da sagt es Geary noch einmal ganz passend selbst: Im Schnitt findet man einen deutlichen Unterschied. Was natürlich noch nicht belegt, dass dieser aus der Biologie kommt. Aber wenn man erst einmal verstanden hat, dass die Biologie in viele Bereiche des menschlichen Verhaltens ganz entscheidend hineinspielt, dann würde es in einem so biologisch unterschiedlichen Bereich stark verwundern, wenn kein Unterschied im Schnitt vorliegt.

The sex difference here and elsewhere is related in part to maternal suckling of infants that can last for several years. But it persists past infancy, and follows more general patterns. Female primates not only gestate and suckle young but are consistently more sensitive to and behaviorally attentive to offspring than are males. This is not to say that these differences are all hormonally or genetically determined—experiences do matter, as Conaboy argues. But nature has not left engagement in the associated behaviors to chance. Nor has it made maternal and paternal brains equally responsive to the associated experiences. In a review of brain imaging studies conducted while parents look at images or film clips of their children, Feldman noted that there is:

greater amygdala activation [associated with emotions] in mothers and greater cortical activation in fathers, suggesting that the hormones of pregnancy may chart a unique limbic path to parenting in mothers, which in fathers is constructed via cortical networks and active caregiving behavior.

Frauen sprechen bereits im Schnitt besser auf das Kindchenschema an (vgl hier und hier). Sie sind im Schnitt stärker auf Personen als auf Dinge bezogen und Mütter, die Karriere machen, wollen im Schnitt meist auch immer noch einen größeren Teil der Kinderbetreuung übernehmen als umgekehrt (kommt mir jedenfalls so vor, bräuchte ich noch mal ne Studie zu, hier eher anekdotisch)

The tendency to see results like these as categorical reflections of women’s and men’s responses to their children only adds to the confusion. These are general trends that are not applicable to each and every mother or father. Within-sex variation in parental behavior is found in both sexes, and in this case, more in men than in women. The variation in maternal and paternal attentiveness and responsiveness to children is partly heritable, but it is also related to the characteristics of parents’ individual children, to their past experiences, and to wider social mores (for instance, marriage rules). This is why, as Conaboy points out, some women describe parenthood as a fabulous and happy experience, while others find it physically and emotionally draining. There is nothing exceptional or unexpected about this variation. Biology will produce female-typical and male-typical biases and behaviors, including in parenting, as well as within-sex variation and cross-sex overlap.

Es dürfte wahrscheinlich mal wieder ein Fall hiervon sein, wobei ich mir vorstellen könnte, dass der summierte Wert aller Unterschiede zu einem relativ großen Unterschied in den Mittelwerten führt.

Was natürlich nicht dazu führt, dass man das nicht dennoch aufteilen kann, wie man es möchte oder wie es jeweils beruflich besser passt.

But the argument that social forces in highly developed Western nations are directing women to maternal activities and restricting their opportunities in the workforce does not survive scrutiny. Sex differences associated with being career-focused versus family-focused are well-documented and show that women are more variable than men when it comes to these trade-offs. A nationally representative survey of adults in the United Kingdom found that 14 percent of women were work-focused (most men are work-focused), 16 percent were home-focused, and the remainder had a mixed home- and work-preference.

Importantly, most women were able to achieve these preferences. Four out of five (or 82 percent of) well-educated and work-focused women had full-time careers, whether or not they had children: “[P]atriarchal values have very little impact, and child care responsibilities have no impact at all on work rates among work-centered women.” If anything, the home-focused women were less able to realize their preferences, as many of them had to work to contribute to family finances. This type of variation among women (and men) follows from sexual reproduction and is a natural part of life.

Aus der oben angeführten Studie:

Longitudinal studies have shown the long-term impact of attitudes, values, and aspirations on labor market behavior and outcomes. However, sociological theory has so far failed to incorporate this new knowledge. Preference theory does so, positing that recent social and economic changes give women genuine choices for the first time in history. A 1999 national survey in Britain shows that women choose three distinct combinations of market work and family work: They have home-centered, work-centered, or adaptive lifestyle preferences. The survey confirms that lifestyle preferences are a major determinant of fertility, employment patterns, and job choice. However, lifestyle preferences no longer determine occupational choice.

Die Studie ist von Catherine Hakim, die ich hier auch schon besprochen habe.

There are two sexes

Sexual reproduction is a milestone in the evolution of planetary life and it is found in one form or another in nearly all eukaryotes (organisms whose cells contain a nucleus). The most fundamental mechanisms that support sexual reproduction are evolutionarily conserved (found across species) and emerged at least 1.5 billion years ago. Early eukaryotes were unicellular organisms, typically with two mating types that produced gametes of about the same size. Competition to merge with the gametes of the other mating type set the stage for the evolution of smaller (sperm) and larger (egg) gametes. These emerged under what biologists call disruptive selection, which favors large or small gametes rather than those in between.

1,5 Milliarden Jahre lang gibt es die zwei Geschlechter. Eine unvorstellbar lange Zeit.

With sperm, you’re buying thousands of lottery tickets—most will be losers but there’s a good chance of hitting a few jackpots. The sperm are built for movement and speed and so don’t carry large caloric or nutritional reserves. If two of them combine there are insufficient reserves to support post-fertilization growth. The larger eggs generally stay put and have the cache of reserves needed to support this growth. Their size means they are more costly to make than sperm and so there are fewer of them.

Die Darstellung der zwei Geschlechter auf einer so frühen Ebene ist interessant. Letztendlich zwei Spezialisierungen in bestimmte Richtungen, bei denen sich der jeweilige Weg als Vorteilhaft dargestellt hat. In der Mitte stehen zu bleiben kann dann im Red Queen Race um den besten Weg dazu führen, dass man hinter beiden zurückbleibt:

Moderate-sized gametes, meanwhile, are outgunned on both sides. They have some reserves but are not as mobile as sperm and there aren’t as many of them. Even if they were fertilized, they cannot support the same level of post-fertilization growth as larger eggs. No doubt they were around following the evolution of sexual reproduction but they were evolutionary dead ends. The result was the evolutionary emergence of individuals who either produced small gametes (sperm, males) or large ones (eggs, females).

In der Mitte ist eben nicht viel Raum für Verbesserung. Wer leicht ist kann schneller werden, wer groß ist kann schneller wachsen, aber wer schneller wachsen will und schneller sein will, der hat zu viele Hindernisse gegen sich.

In other words, sexual reproduction has independently evolved in different groups of plants and animals and has always arrived at the same solution—two sexes distinguished by the size of the respective gametes they produce. In some species, sex can change depending on ecological or social conditions, changes that typically improve their reproductive success. Some reef fish, for example, might transition from female to male as they grow larger, if large males can monopolize breeding territories and thus reproduce with lots of females. But this type of sex change does not occur in mammals (or birds). Sex is therefore a categorical binary.

Da hatten wir hier auch schon viele Artikel und Diskussionen zu:

• Warum es in biologischer Hinsicht nur zwei Geschlechter gibt
• Gibt es mehr als zwei menschliche Geschlechter?
• „Wie viele verdammte Geschlechter gibt es? Nur zwei“ (Laci Green)
• „Es gibt über 90 Paprikasorten“ vs „es gibt 2 Geschlechter“
• Nüsslein-Volhardt in der Emma: Es gibt nur zwei Geschlechter
• Intersexuelle als Falsifikation der Theorie von den zwei Geschlechtern
• „Es gibt nur zwei Geschlechter – Ändere meine Meinung“
• Zwei Geschlechter und Binarität bzw Polarität

The existence of two sexes does not mean that males always behave in evolved male-typical ways and females in female-typical ways. The picture is complicated by human self-awareness and by psychological and social issues that can arise from engaging in sex-atypical behaviors. Engagement in these activities (such as doll play for boys) can undermine acceptance by peers and result in a higher risk of psychological issues like depression, especially for boys. Engagement in behaviors that are more typical of the other sex might result in preferring the other sex as playmates or friends, at least at times, but this is not the same as wanting to physically become the other sex.

In der Tat werden die meisten der sehr männliche Mädchen sich eben als Mädchen sehen aber lieber mit Jungs abhängen. Oder sehr weibliche Mädchen doof finden. Das alles macht sie nicht zu Männern. Butchlesben mögen vieles mit Männer teilen und sehen oft auch männlicher aus aber sehen sich eben gerade als (lesbische) Frauen, die sie auch bleiben wollen.

Most people (more than 99 percent, in fact), including those with interests more common to the opposite sex, psychologically identify as the sex of their birth. A tiny minority of people with gender dysphoria desire to be seen as the opposite sex and will medically transition, but this is not as common as implied by activists (or the attention currently devoted to the issue), nor would we expect it to be common from a biological perspective.

In der Tat wäre ein sehr hohes Aufkommen aufgrund rein biologischer Tatsachen erst einmal etwas verwunderliches in einer Spezies mit deutlichen biologischen Unterschieden, zumal über die aller längste Zeit unserer Evolution dem Gefühl im falschen Körper zu stecken schlicht nicht abgeholfen werden konnte.

The origins of sex differences

There are, of course, many similarities in the behaviors and other traits of males and females in most species, but there are also well-understood differences that are common across species. Differences are typically associated with different approaches to reproduction, as detailed by Charles Darwin more than 150 years ago. These approaches generally turn on relative contributions to parenting, with the higher investing sex being choosier when it comes to mates and the other sex competing for access to mates. This typically manifests as male-male competition and female choice, although there are species in which females are more competitive and males invest more in parenting. Female parenting and higher investment in offspring are built into the biology of reproduction for mammals, with internal gestation and postpartum suckling. Males provide considerable care in some mammals, but it’s not the norm. Instead, males generally attack one another or compete in other ways to gain social status with which to attract females.

Wie ich oben bereits schrieb: Es wäre verwunderlich, wenn das Geschlecht, welches mit Drüsen zur Ernährung des Kindes ausgerüstet ist, nicht auch ansonsten eine gewisse Selektion auf Kinderbetreuung durchlaufen hat, die dazu führt, dass es den Nachwuchs, den nur es über die erste Zeit versorgen kann, nicht auch versorgen will oder dies zumindest schmackhafter macht. Natürlich ist es daneben ebenso gut, wenn der Vater Betreuungsleistungen übernehmen kann, aber in der Tat läuft eine Evolution daneben sich in der intrasexuellen Konkurrenz auf einem guten Platz zu behaupten.

For primates, a sex difference in physical size is a good indicator of the extent to which males focus on competing for mates rather than investing in offspring. If males are on average larger than females, this is generally associated with a polygynous mating system, whereby dominant males have offspring with many females and many low-status males never reproduce at all. Sometimes, these males provide protection to offspring (for example, gorillas) but females provide most of the direct parental care. When males provide social protection or other resources, females compete to develop relationships with them, as is found in several species of Savanah baboon. In these cases, we see female-female competition and male choice, along with male-male competition and female choice.

Das ist erst einmal eine Darstellung des Systems, wie man es in der Natur vorfindet. In der Tat macht es gerade körperliche intrasexuelle Konkurrenz interessant größer und stärker zu werden, wobei auch die Arbeitsteilung, die ja beim Menschen sehr stark ausgeprägt ist (Frauen haben der Forschung nach nie Großwildjagd übernommen) seinen Teil dazu beigetragen.

Human sex differences in physical size and many associated traits related to intense physical competition fit nicely with this general pattern. In fact, larger males than females date back at least four million years in our ancestry. Some have argued that these patterns are the result of a sexual division of labor and monogamy, whereby males provisioned females and offspring. But this is unlikely, given the general pattern in primates and that intense male-male competition and polygyny are the norm in traditional societies. In any event, the fact that human sex differences are real and have a strong biological basis does not imply genetic determinism. Sex differences are not socially constructed from whole cloth, but their expression can be exaggerated, suppressed, or deflected to be expressed in different ways by local conditions and social rules such as marriage laws or customs.

Also das übliche: Nicht Nature vs Nurture, sondern eine Wirkung beider Faktoren, wobei eben durchaus die Biologie gewisse Grenzen setzen kann bzw eine Erziehung in eine Richtung deutlich erschweren kann.

Still, sex differences in physical traits are well-documented and cannot simply be argued away. Hyde acknowledges some large differences, such as throwing distance, but argues that these are exceptions and that most differences are small. Archer later pointed out that there are quite a few individual traits with large sex differences, including very large differences in homicide rates, which can be 30 to 40 times more common among males (typically killing male rivals) than females, as well as large differences in fearfulness in real-world contexts (85–90 percent of girls and women are more fearful than the average boy or man) or pain tolerance (almost 90 percent of boys and men have a higher pain threshold than the average girl or woman). As Del Giudice and colleagues have argued, the real differences are found in the pattern of related traits.

Del Giudice et al:

Abstract
Background
Sex differences in personality are believed to be comparatively small. However, research in this area has suffered from significant methodological limitations. We advance a set of guidelines for overcoming those limitations: (a) measure personality with a higher resolution than that afforded by the Big Five; (b) estimate sex differences on latent factors; and (c) assess global sex differences with multivariate effect sizes. We then apply these guidelines to a large, representative adult sample, and obtain what is presently the best estimate of global sex differences in personality.
Methodology/Principal Findings
Personality measures were obtained from a large US sample (N = 10,261) with the 16PF Questionnaire. Multigroup latent variable modeling was used to estimate sex differences on individual personality dimensions, which were then aggregated to yield a multivariate effect size (Mahalanobis D). We found a global effect size D = 2.71, corresponding to an overlap of only 10% between the male and female distributions. Even excluding the factor showing the largest univariate ES, the global effect size was D = 1.71 (24% overlap). These are extremely large differences by psychological standards.
Significance
The idea that there are only minor differences between the personality profiles of males and females should be rejected as based on inadequate methodology.

Den Artikel hatte ich auch bereits hier besprochen.

It’s not that male-male fighting produced the evolution of taller men; it selected for a suite of correlated and co-evolving traits, including height, cardiovascular capacity, skeletal structure, bone density, lean muscle mass, as well as some less obvious traits. As with other primates with a history of physical competition, these include sex differences in brain areas involved in sensorimotor integration and aggression that support deft behavioral and emotional reactions to physical attacks. In traditional contexts and historically, male-male competition included the use of blunt force and projectile weapons. The latter favors strong throwing accuracy and velocity, as well as enhancement of the brain and cognitive systems that support the tracking of objects moving through space and integration of these systems with those that support throwing accuracy and the ability to dodge projectiles. Boys and men have advantages in all these individual areas. The sex difference for each individual trait ranges from small to quite large. The critical point is that their combination is integrated into a uniquely male suite of correlated traits.

Auch interessante Studien:

Novel findings from 2,838 Adult Brains on Sex Differences in Gray Matter Brain Volume

There is still disagreement among studies with respect to the magnitude, location, and direction of sex differences of local gray matter volume (GMV) in the human brain. Here, we applied a state-of-the-art technique examining GMV in a well-powered sample (n = 2,838) validating effects in two independent general-population cohorts, age range 21–90 years, measured using the same MRI scanner. More GMV in women than in men was prominent in medial and lateral prefrontal areas, the superior temporal sulcus, the posterior insula, and orbitofrontal cortex. In contrast, more GMV in men than in women was detected in subcortical temporal structures, such as the amygdala, hippocampus, temporal pole, fusiform gyrus, visual primary cortex, and motor areas (premotor cortex, putamen, anterior cerebellum). The findings in this large-scale study may clarify previous inconsistencies and contribute to the understanding of sex-specific differences in cognition and behavior.

Multilevel Mapping of Sexual Dimorphism in Intrinsic Functional Brain Networks

Differences in cognitive performance between males and females are well-described, most commonly in certain spatial and language tasks. Sex-related differences in cognition are relevant to the study of the neurotypical brain and to neuropsychiatric disorders, which exhibit prominent disparities in the incidence, prevalence and severity of symptoms between men and women. While structural dimorphism in the human brain is well-described, controversy exists regarding the existence and degree of sex-related differences in brain function. We analyzed resting-state functional MRI from 650 neurotypical young adults matched for age and sex to determine the degree of sexual dimorphism present in intrinsic functional networks. Multilevel modeling was pursued to create 8-, 24-, and 51-network models of whole-brain data to quantify sex-related effects in network activity with increasing resolution. We determined that sexual dimorphism is present in the majority of intrinsic brain networks and affects ∼0.5–2% of brain locations surveyed in the three whole-brain network models. It is particularly common in task-positive control networks and is pervasive among default mode networks. The size of sex-related effects varied by network but can be moderate or even large in size. Female > male effects were on average larger, but male > female effects spread across greater network territory. Using a novel methodology, we mapped dimorphic locations to meta-analytic association test maps derived from task fMRI, demonstrating that the neurocognitive footprint of intrinsic neural correlates is much larger in males. All results were replicated in a motion-matched sub-sample. Our findings argue that sex is an important biological variable in human brain function and suggest that observed differences in neurocognitive performance have identifiable intrinsic neural correlates.

Gender differences across age in motor performance: A meta-analysis.

Conducted a meta-analysis of 64 studies that reported gender differences on motor performance during childhood and adolescence. Findings yielded 702 effect sizes based on data from 15,518 female and 15,926 male 3–20 yr olds. Age was regressed on effect size, and the relation was significant for 12 of 20 tasks (e.g., balance, catching, grip strength, shuttle run, throw velocity, tapping). Several types of age-related curves were found; the curve for a throwing task was the most distinctive. Five of the tasks followed a typical curve of gender differences across age. For 8 tasks, gender differences were not related to age, and effect sizes were small. Results are discussed in relation to the development of gender differences to biological and environmental sources. A bibliography of the 64 studies is appended. (47 ref) (APA PsycInfo Database Record (c) 2016 APA, all rights reserved)

Nontrivial sex differences in throwing and intercepting: Relation to psychometrically-defined spatial functions

Biological sex is a marked individual difference, yet sex differences obtained on cognitive tests are often slight. In general, males excel on psychometric tests of spatial ability, whereas females enjoy an advantage on tests of verbal and fine motor ability. In a previous study on hand preferences, substantial sex differences favouring males were found on two target-directed motor tasks: dart-throwing and projectile interception. This advantage was not readily attributable to sex differences in physique or athletic experience.

Such tasks may employ a more fundamental form of spatial ability, relating to real world target analysis. In the present study, these sex differences were examined along with established measures of spatial function, and a novel visualization test (Viewfinding Test). In contrast to the large sex differences found for the motor tasks, only weak trends were found on the paper-and-pencil spatial tests. Males were significantly better on the Viewfinding Test, however. The paper-and-pencil tasks and the Viewfinding Task generally intercorrelated amongst themselves, but were uncorrelated with accuracy on the target-directed motor tasks. Thus, target-directed motor tasks may employ a type of spatial function that is somewhat separable from traditionally-measured spatial abilities. The importance of human ethology for the study of sex differences is discussed.

The same is true for girls and women, who typically don’t physically fight but do engage in relational aggression that includes manipulating social information in ways that undermine the reputation of competitors and disrupt their social-support networks and access to would-be mates. Among other things, competence at relational aggression and skill at detecting and avoiding it is supported by a host of social-cognitive competencies (sometimes called emotional intelligence). These skills are also used to build cooperative friendships and include (among others) aspects of language, reading facial expressions, body posture, and gestures, and drawing inferences about the thoughts and feelings of others (called theory of mind).

Männer und Frauen tragen ihre intrasexuelle Konkurrenz eben anders aus.

Girls’ and women’s advantages in these individual areas are generally small to moderate, but in the real world, they work in combination. Here the differences are large; almost nine out of 10 women outperform the average man on tasks that involve their integration. In traditional contexts, female-female relational aggression is common, especially among women in polygynous marriages, and women who are skilled at navigating these relationships generally have more and healthier children.

Female Aggression in Cross-Cultural Perspective

This paper presents findings from a preliminary cross-cultural survey of adult human female aggression. Cases of female-initiated aggression, ranging from verbal abuse to murder, are found in all regions ofthe world. Female aggression is largely directed against other females and generally involves little injury. Co-wives and other rivals in sex andmarriage are the most common victims. Husbands are the most common male targets. Female aggression is often a means of competing for men or subsistence products, but it may also be a means of defense.

Sex differences in the brain

The extent of sex differences in the brain, cognition (for example, spatial abilities), and behavior (for example, personality) continue to be vigorously debated. But minimalists tend to focus on individual behavioral and psychological traits when making their case. Hyde, for instance, argues that most of these differences (such as self-esteem) are small or close to zero. But while single psychological traits are interesting and useful to study, they do not stand alone in the real world. Like physical traits, they are components of more complicated and integrated systems, and sex differences in these suites of traits are much larger than those found for the individual components.

Brains are a mosaic of integrated regions that in most areas are more similar than different across boys and girls and men and women. At the same time, we would expect sex differences in the brain to be distributed across regions that are integrated into functional systems (areas that work in concert), such as those that support physical fighting or simultaneously processing and responding to different forms of social information (language, gesture, and so on). The result would be small to moderate differences in some areas, but potentially large differences in whole-brain patterns.

Die Studie zum Gehirn-Mosaik hatte ich hier besprochen.

 

These patterns are the key to fully understanding sex differences. For individual personality traits, such as emotional stability (about seven out of 10 men are more stable than the average woman) or social agreeableness (about three out of five women are more agreeable than the average man), there are small to moderate differences. These are interesting and important, but if we look at the entire structure of personality, including things like risk-taking, openness to new ideas and experiences, conscientiousness, and so forth, the differences are now two to five times larger than they are for these individual traits.

Um es am Körper zu erklären: Wer etwas kräftiger ist, etwas längere Arme hat, ein höherers Gewicht, stabilere Knochen, dickere Haut, weniger Schmerzempfindlich ist etc der wird insgesamt besser Eigenschaften als Kämpfer haben, selbst wenn die Unterschiede für sich genommen klein erscheinen möge.

One study examined the patterns of grey and white matter in the brains of nearly 10,000 boys and girls and asked whether the sex of the child could be determined by these patterns. They can. The sex of 93 percent of the children was correctly identified. Histograms of the numbers of boys and girls with male-typical and female-typical brain patterns are shown in the figure below.

Histograms of brain-based sex score for boys (left) and girls (right). Adapted from K. Kim et al. (p. 3864). Creative commons.

As can be seen, most boys (left side of figure) and girls (right side) have grey and white matter patterns that are sex-typical (highly like other members of the same sex) and substantively different than those of the opposite sex. There are boys and girls with brain patterns that are in between male- and female-typical patterns and some with patterns found in the opposite sex, in keeping with natural within-sex variation.

Eine interessante Studie:

The sexual brain, genes, and cognition: A machine-predicted brain sex score explains individual differences in cognitive intelligence and genetic influence in young children

Sex impacts the development of the brain and cognition differently across individuals. However, the literature on brain sex dimorphism in humans is mixed. We aim to investigate the biological underpinnings of the individual variability of sexual dimorphism in the brain and its impact on cognitive performance. To this end, we tested whether the individual difference in brain sex would be linked to that in cognitive performance that is influenced by genetic factors in prepubertal children (N = 9,658, ages 9–10 years old; the Adolescent Brain Cognitive Development study). To capture the interindividual variability of the brain, we estimated the probability of being male or female based on the brain morphometry and connectivity features using machine learning (herein called a brain sex score). The models accurately classified the biological sex with a test ROC–AUC of 93.32%. As a result, a greater brain sex score correlated significantly with greater intelligence (pfdr < .001, ηp2 = .011–.034; adjusted for covariates) and higher cognitive genome-wide polygenic scores (GPSs) (pfdr < .001, ηp2 < .005). Structural equation models revealed that the GPS-intelligence association was significantly modulated by the brain sex score, such that a brain with a higher maleness score (or a lower femaleness score) mediated a positive GPS effect on intelligence (indirect effects = .006–.009; p = .002–.022; sex-stratified analysis). The finding of the sex modulatory effect on the gene–brain–cognition relationship presents a likely biological pathway to the individual and sex differences in the brain and cognitive performance in preadolescence.

We don’t know if brain patterns that are more like those of the opposite sex are associated with behaviors and interests that are more common in the opposite sex, but it seems likely that they are. Girls with prenatal exposure to male hormones engage in more male-typical behavior than other girls and are less interested in infants and more likely to be work-focused. Men with a cellular insensitivity to testosterone have female-typical brain activity patterns during spatial tasks, suggesting a more feminine brain.

Die Studien:

Early androgen effects on interest in infants: Evidence from children with congenital adrenal hyperplasia

Early androgens have been shown to facilitate male‐typical behavior in people, but little attention has been paid to androgen effects on female‐typical behavior. We studied the effects of early androgen on human interest in infants, attempting to extend studies in rodents and primates that indicate that exposure to high levels of androgen in the prenatal and early postnatal periods reduces the expression of maternal behavior in juvenile and adult animals. Parents completed a questionnaire about the behavior of children with congenital adrenal hyperplasia (CAH) who had been exposed to high levels of androgens early in life, and their unexposed siblings. As hypothesized, girls with CAH were reported to have less interest in infants than their sisters. These results suggest that early androgens may act to suppress some aspects of female‐typical behavior in people, as in other species, and that sex differences in maternal behavior result, in part, from early hormones.

vgl auch:

• CAH-Mädchen und die Auswirkung pränataler Hormone auf das Verhalten
• Congenital adrenal hyperplasia (CAH)

und:

Neural Activation During Mental Rotation in Complete Androgen Insensitivity Syndrome: The Influence of Sex Hormones and Sex Chromosomes

Abstract
Sex hormones, androgens in particular, are hypothesized to play a key role in the sexual differentiation of the human brain. However, possible direct effects of the sex chromosomes, that is, XX or XY, have not been well studied in humans. Individuals with complete androgen insensitivity syndrome (CAIS), who have a 46,XY karyotype but a female phenotype due to a complete androgen resistance, enable us to study the separate effects of gonadal hormones versus sex chromosomes on neural sex differences. Therefore, in the present study, we compared 46,XY men (n = 30) and 46,XX women (n = 29) to 46,XY individuals with CAIS (n = 21) on a mental rotation task using functional magnetic resonance imaging. Previously reported sex differences in neural activation during mental rotation were replicated in the control groups, with control men showing more activation in the inferior parietal lobe than control women. Individuals with CAIS showed a female-like neural activation pattern in the parietal lobe, indicating feminization of the brain in CAIS. Furthermore, this first neuroimaging study in individuals with CAIS provides evidence that sex differences in regional brain function during mental rotation are most likely not directly driven by genetic sex, but rather reflect gonadal hormone exposure.

This is not an anomalous finding. Brain patterns can be used to correctly identify whether the owner is a man or a woman with 93 to 96 percent accuracy. By analogy, the human face is also a suite of traits with overlap across females and males in the size of core features (for example, the area of the eyes) but the sex of the individual is easily determined by most people. At the same time, studies like these ignore areas where boys and girls and men and women are similar and use crude computer algorithms to identify areas that best discriminate one sex from the other, without considering whether these differences are components of integrated systems.

One way to assess the latter is to examine patterns of spontaneous activity that often reflect the synchronized activation of integrated and distributed brain networks that support functional systems, such as language comprehension and production. These types of studies can now be conducted prenatally and reveal distinct brain networks in four- to six-month-old fetuses. Synchronized activity across different brain areas helps to build and strengthen these systems, and there are sex differences even at this age. At least some later sex differences in brain organization appear to have their roots in prenatal development. A recent study found that the sex of 83 percent of eight- to 23-year-olds could be correctly identified based on differences in the spontaneous activity patterns of different brain networks that in turn were associated with sex differences in patterns of gene expression. Some of these functional brain-network differences have been linked to sex differences in social information processing, although much remains to be learned.

Sex differences in functional connectivity during fetal brain development

Sex-related differences in brain and behavior are apparent across the life course, but the exact set of processes that guide their emergence in utero remains a topic of vigorous scientific inquiry. Here, we evaluate sex and gestational age (GA)-related change in functional connectivity (FC) within and between brain wide networks. Using resting-state functional magnetic resonance imaging we examined FC in 118 human fetuses between 25.9 and 39.6 weeks GA (70 male; 48 female). Infomap was applied to the functional connectome to identify discrete prenatal brain networks in utero. A consensus procedure produced an optimal model comprised of 16 distinct fetal neural networks distributed throughout the cortex and subcortical regions. We used enrichment analysis to assess network-level clustering of strong FC-GA correlations separately in each sex group, and to identify network pairs exhibiting distinct patterns of GA-related change in FC between males and females. We discovered both within and between network FC-GA associations that varied with sex. Specifically, associations between GA and posterior cingulate-temporal pole and fronto-cerebellar FC were observed in females only, whereas the association between GA and increased intracerebellar FC was stronger in males. These observations confirm that sexual dimorphism in functional brain systems emerges during

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Sex differences in the functional topography of association networks in youth

Significance
We identified normative sex differences in the functional topography of personalized association networks, including the ventral attention, default mode, and frontoparietal networks. Furthermore, chromosomal enrichment analyses revealed that sex differences in multivariate patterns of functional topography were spatially coupled to the expression of X-linked genes as well as astrocytic and excitatory neuronal cell–type signatures. These results highlight the role of sex as a biological variable in shaping functional topography.
Abstract
Prior work has shown that there is substantial interindividual variation in the spatial distribution of functional networks across the cerebral cortex, or functional topography. However, it remains unknown whether there are sex differences in the topography of individualized networks in youth. Here, we leveraged an advanced machine learning method (sparsity-regularized non-negative matrix factorization) to define individualized functional networks in 693 youth (ages 8 to 23 y) who underwent functional MRI as part of the Philadelphia Neurodevelopmental Cohort. Multivariate pattern analysis using support vector machines classified participant sex based on functional topography with 82.9% accuracy (P < 0.0001). Brain regions most effective in classifying participant sex belonged to association networks, including the ventral attention, default mode, and frontoparietal networks. Mass univariate analyses using generalized additive models with penalized splines provided convergent results. Furthermore, transcriptomic data from the Allen Human Brain Atlas revealed that sex differences in multivariate patterns of functional topography were spatially correlated with the expression of genes on the X chromosome. These results highlight the role of sex as a biological variable in shaping functional topography.

Schon faszinierend, wie wir unser Gehirn und die Unterschiede zwischen den Geschlechtern immer mehr verstehen und sich das Bild immer mehr verdeutlicht.

Sex differences in anatomical and functional brain networks have not yet been fully integrated with what we know about sex differences in behavior and cognition, nor fully integrated within an evolutionary perspective. But there has been considerable progress. Despite these current gaps in our knowledge, the findings noted here and in many other neuroscience studies are not consistent with 52 genders, nor are they consistent with the social construction of gender or gender/sex differences. To be sure, there are social and cultural influences on the expression of these differences, as noted, but the argument that they are purely (or mostly) the product of social forces is simply untrue, and that includes Chelsea Conaboy’s claims about parenting.

Wer heute noch eine Theorie vertritt nach der eine rein soziale Konstruktion der Geschlechter vorliegt, der hat einiges an Erklärungsbedarf.

The bottom line

The claims made in a virtual world of internet algorithms populated by ideological social media pundits, journalists, and gender studies professors contradicts common sense and rational analysis of real-world phenomena. This is a world of words and ideas fraught with wishes and desires that are not always tethered to reality, including many far-fetched beliefs about the number of sexes and the origins and malleability of any associated sex or gender differences. Much remains to be learned about these differences which leaves plenty of room for legitimate debate. But there is no scientific room for the nonsensical idea that boys and girls and men and women are infinitely malleable and merely socially constructed products of the patriarchy or some other social system.

Weitere Artikel zu David Geary:

• David Geary: Male, Female
• Gründe für Geschlechterunterschiede in STEM: Teile 1,2,3,4,5,6, 7
• Geschlechtsspezifische akademische Fähigkeiten und Einstellungsmuster bei Schülern in entwickelten Ländern
• Ein neues, einfacheres Verfahren zur Messung von Geschlechtergleichberechtigung in Ländern
• Das Bateman-Prinzip, feministische Wissenschaft und das Unwissen der Mädchenmannschaft bezüglich der Biologie
• Stereotype threat und Frauen in der Mathematik
• Männerfreundschaften und Koalitionsbildung
• Vaterschaft und Evolution
• Heiratsformen und Familienstrukturen
• Das Gender Equality Paradox in den Naturwissenschaften, Technology und den Ingenieurwissenschaften sowie der Mathematik
• Geschlechtsspezifische Unterschiede bei den Berufswünschen Jugendlicher: Variationen über Zeit und Ort: (Teil 1): Einleitung und Geschlechterunterschiede in den Berufswünschen und der Berufswahl
• David Geary „Evolution of trait vulnerabilites“