Studies indirectly related to (prenatal) testosterone

Dominant (high testosterone?) personalities get paid more

"Dominant, assertive women, who clearly express their expectations and do not retreat from their demands, are compensated better than their more accommodating female peers. According to the researchers, the same goes for dominant men versus their more conciliatory male counterparts [...]."

('Nice' women earn less than their more assertive counterparts, ScienceDaily, nov.21st 2016)

High testosterone type men more likely to have psychological problems

"Men who see themselves as playboys or as having power over women are more likely to have psychological problems than men who conform less to traditionally masculine norms [...].
Specifically, they focused on three broad types of mental health outcomes: negative mental health (e.g., depression), positive mental health (e.g., life satisfaction), and psychological help seeking (e.g., seeking counseling services). [...]
While overall, conforming to masculine norms was associated with negative mental health outcomes in subjects, the researchers found the association to be most consistent for these three norms -- self-reliance, pursuit of playboy behavior, and power over women."

(Sexism may be harmful to men's mental health, ScienceDaily, nov.21 2016)

Trauma changes brain differently in boys than in girls

"Within [the insula's anterior circular sulcus], boys with PTSD (Post-Traumatic Stress Disorder) symptoms demonstrated larger volume and surface area than control boys, while girls with PTSD symptoms demonstrated smaller volume and surface area than control girls."

(Klabunde, Megan, et al. "The moderating effects of sex on insula subdivision structure in youth with posttraumatic stress symptoms." Depression and Anxiety (2016).)

Dominance (high testosterone?) related to psychopathology, mania and narcissism

"Extensive research suggests that externalizing disorders, mania-proneness, and narcissistic traits are related to heightened dominance motivation and behaviors. Mania and narcissistic traits also appear related to inflated self-perceptions of power. Anxiety and depression are related to subordination and submissiveness, as well as a desire to avoid subordination."

(Johnson, Sheri L., Liane J. Leedom, and Luma Muhtadie. "The dominance behavioral system and psychopathology: evidence from self-report, observational, and biological studies." Psychological bulletin 138.4 (2012): 692.)

"[N]arcissism is positively associated with dominance (Bradlee & Emmons, 1992; Emmons, 1987; Raskin & Terry, 1988)."

(Grijalva, Emily, and Peter D. Harms. "Narcissism: An integrative synthesis and dominance complementarity model." The Academy of Management Perspectives 28.2 (2014): 108-127.)

Higher rates of homosexuality, bisexuality and asexuality among people with autism

"In the group with ASD (Autism Spectrum Disorder), 69.7% of the sample reported being non-heterosexual, while in the TD (Typically Developing) group, 30.3% reported being non-heterosexual. The group with ASD reported higher rates of homosexuality, bisexuality and asexuality, but lower rates of heterosexuality. The results support the impression that non-heterosexuality is more prevalent in the autistic population."

(George, R., and M. A. Stokes. "Sexual Orientation in Autism Spectrum Disorder." Autism Research.)

Estrogens from contraceptive pill implicated in agressive behavior

"Ethinylestradiol (EE2) is a widely produced, powerful synthetic estrogen that is widespread in the environment mainly because is a component of the contraceptive pill. In addition, fetuses may be exposed to EE2 when pregnancy is undetected during contraceptive treatment. To understand whether exposure to EE2 during gestation or lactation affects social play, we exposed 72 female Sprague-Dawley rats to EE2 or vehicle either during gestation (gestation day (GD) 5 through GD 20) or during lactation (from postnatal day (PND) 1 through PND 21). Two doses of EE2 were used to treat the dams: a lower dose in the range of possible environmental exposure (4 ng/kg/day) and a higher dose equivalent to that received during contraceptive treatment (400 ng/kg/day). Behavioral testing was carried out between PND 40 and 45. A principal component analysis of frequencies of behavioral items observed during play sessions identified three main components: defensive-like play, aggressive-like play, and exploration. Aggressive-like play was significantly increased by both doses of EE2, and the gestational administration was in general more effective than the lactational one. Defensive-like play and exploration were not significantly affected by treatment. This research showed that low and very low doses of EE2 that mimic clinical or environmental exposure during development can affect important aspects of social behavior even during restricted time windows."

(Zaccaroni, Marco, et al. "Developmental Exposure to Low Levels of Ethinylestradiol Affects Play Behavior in Juvenile Female Rats." Neurotoxicity Research (2017): 1-11.)

Endocrine disrupting chemicals are devastating the biosphere

(Translation from Portuguese to English by Google Translate)

"Introduction to the theme: With the unraveling of the various technological revolutions (industrial revolution, green revolution, among others), from generation to generation, the molecular pattern to which we are exposed on a daily basis has changed. This change culminated in significant impacts on our biology and, along with it, on our health and disease processes. Unrestricted to us, we are slowly altering the chemistry of the biosphere, bringing devastating consequences to the myriad forms of life on earth - as Rachel Carson brilliantly stated, "in nature, there is nothing alone."
Theoretical course: [...] [A] number of molecules with chemical similarity to female hormones can promote endocrine disruption, blocking [sexual] differentiation at certain points. Among the molecules, many of them are fruits of modern chemical revolutions, such as phthalates (widely present in plastics and plasticizers), pesticides, herbicides, some drugs, smoking, and other household products that have become our market list. (...)
Conclusion: At the dawn of technological revolutions, a problem arises not only of public health, but also of the environment: we are destroying a biological equilibrium slowly shaped by tens of thousands of years. We are stealing the future not only of our children, but of whole specimens. Such a problem permeates the political bed. And with chronic public disregard for science, fewer and fewer people are able to question this type of problem and call for change and improvement. This problem plagues our future and, as a true science, must be debated and disseminated."

(Müller, Juliane Centeno, et al. "A DISTÂNCIA ANOGENITAL DOS RECÉM-NASCIDOS E SUA PROFUNDA RELAÇÃO COM A BIOSFERA.")

Engineering culture discriminates empathizing brains

"This paper reviews relevant research on how systemizing-empathizing (S-E) theory applies to engineering education and examines current research on the reasons behind the dearth of females in engineering, finding that the contemporary engineering culture in college is also characterized by subtle forms of discrimination that systematically direct women away from engineering."

(Fertig, Jan, and Subha Kumpaty. "Gender Issues in Engineering Education: What Systemizing and Empathizing Have to Do With It." ASME 2017 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2017.)

Male brains perceive themselves as more intelligent than female brains, even if they score the same grades

A first-of-its-kind study shows that in the college biology classroom, men perceive themselves as smarter, even when compared to women whose grades prove they are just as smart. (...)
Katelyn Cooper, a doctoral student in the Arizona State University School of Life Sciences and lead author of the study, has talked with hundreds of students as an academic advisor and those conversations led to this project.
"I would ask students about how their classes were going and I noticed a trend," shared Cooper. "Over and over again, women would tell me that they were afraid that other students thought that they were 'stupid.' I never heard this from the men in those same biology classes, so I wanted to study it."

(Arizona State University. "Who's smarter in the classroom -- men or women? New study shows it's all about perception." ScienceDaily. ScienceDaily, 4 April 2018.)

Women (in general) experience pleasure when cooperating, men (in general) when they are cheating

"What we're going to see later is something very interesting: people playing [the Prisoner's Dilemma game] inside a brain scanner, [while the researchers are] looking into a part of the brain that has a lot to do with pleasure, and what you see is [that] some individuals activate that part of the brain when they've successfully stabbed the other guy in the back, some individuals activate it when they have both cooperated, and there's a big gender difference as to which circumstance. So you just guess which one is going on there (...)."

(March 31, 2010, Stanford professor Robert Sapolsky lectures on the biology of behavioral evolution, Youtube, "2. Behavioral Evolution", 44:36 - 45:04)

Men willing to punish more than women to get ahead

'Chapman University has published research measuring gender differences in cooperation and punishment behavior. Results showed that men punish more than women, men obtain higher rank, and punishment by males decreases payoffs for both sexes. Furthermore, men are willing to punish people who have done nothing wrong, except cooperate to the fullest extent possible. 

Results suggest that status-seeking men are willing to impose enormous costs on others and destroy their group to move up in the hierarchy. According to the study, men may punish more than women for two reasons: First, punishment is often viewed as similar to physical conflict. Men are known to favor physical punishment of unfair behavior. Men are also less cooperative and less generous compared with their female counterparts.
Second, status affects cooperative behavior and women may feel differently about status and rank. If so, punishment may be a tool used by certain individuals to advance in rank. For example, explicit rank-based incentives caused men to punish at roughly twice the rate of women. 

"Outside the laboratory, high-powered punishment and rank-based reward may be the norm," said Terence Burnham, Ph.D, associate professor in Chapman University's Argyros School of Business and Economics, and sole author of this study.'

(Chapman University. "Men willing to punish more than women to get ahead: New research evaluates gender differences in cooperation." ScienceDaily. ScienceDaily, 16 April 2018. )

There are much more severely antisocial males than females

"Males greatly outnumber females in the most severe forms of antisocial behavior."

(Eme, Robert. "Sex differences in temperament: A partial explanation for the sex difference in the prevalence of serious antisocial behaviors." Aggression and Violent Behavior (2018).

Men are more risk taking, overconfident, more willing to hurt others than women

Considerable evidence that women are significantly more averse to taking risks

Why?
▪ Emotions: Women report more nervousness and fear in anticipation of negative outcomes
▪ Overconfidence: Men being more overconfident in their success in uncertain situations
▪ Perception of risk: Men are more likely to see a risky situation as a challenge while females women risky situations as threats
(citing Croson, Rachel, and Uri Gneezy. 2009. "Gender Differences in Preferences." Journal of Economic Literature, 47 (2): 448-74, DOI: 10.1257/jel.47.2.448)
(...)

Why do women compete less?

▪ Differences in performance: Not the case in arithmetic
▪ Differences in beliefs: Men are overconfident
▪ Preferences for risk: Women are more risk averse
▪ Differences in altruism: Women do not want to hurt others
▪ Aversion to competition: Women dislike performing in competitions
(...)

Evidence of overconfidence, particularly by men

Men:
% expecting to be 1st 75%
Of those expecting to be 1st, 27% were actually first
Women
% expecting to be 1st 43%
Of those expecting to be 1st, 47% were actually first
(citing Niederle, Muriel, and Lise Vesterlund. "Do women shy away from competition? Do men compete too much?." The Quarterly Journal of Economics 122.3 (2007): 1067-1101.)
(...)

Women avoid performing in competitive environments

Replicated many times
Why a gap in tournament entry?
▪ Beliefs: gap weakens in tasks where women are expected to perform better (e.g. verbal tasks) and when feedback about relative performance is given
▪ “Culture”: gap weakens when competition is for teams and not individuals, in matrilineal societies, among young children, and for girls who attend same-sex schools
(citing Niederle, Muriel, and Lise Vesterlund. "Gender and competition." Annu. Rev. Econ. 3.1 (2011): 601-630.)

(EXPERIMENTAL ECONOMICS - GENDER, presentation by Ernesto reuben, associate professor in the Social Science Division, New York University, Abu Dhabi)

Substantial differences between female and male brains in mice

Scientists studying the locus coeruleus brain structure in mice unexpectedly found substantial differences in the molecular structures of this part of the brain between male and female mice.

(Cell Press. "Mice brain structure linked with sex-based differences in anxiety behavior." ScienceDaily. ScienceDaily, 22 May 2018. )

Teenage girls are more impacted by sleepiness than teen boys are

"What was most surprising is the fact that teenage girls reported a higher degree of interference of daytime sleepiness than teenage boys on multiple aspects of their school and personal activities," said co-author Pascale Gaudreault, who is completing her doctoral degree in clinical neuropsychology (...)."

(American Academy of Sleep Medicine. "Teenage girls are more impacted by sleepiness than teen boys are: Sleep disturbances in girls associated with more difficulties staying awake in and out of school." ScienceDaily. ScienceDaily, 6 June 2018.)

Gender is not purely a social construct

"We suggest, however, that the evidence for gender being purely a social construct is limited and neither necessary nor accepted as such within andrology. (...) Many problems in men’s health that have been assumed to be the products of enculturation have in fact a biological basis."

(Tsang, Vivian WL, and Richard J. Wassersug. "Men’s Health Research versus Andrology—Defining the Division and Closing the Divide."(PDF download) Journal of Men's Health 14.3 (2018): e20-e32.)

Study finds less corruption in countries where more women are in government

"In a cross-country analysis of over 125 countries, this study finds that corruption is lower in countries where a greater share of parliamentarians are women. The study further finds that women's representation in local politics is important too -- the likelihood of having to bribe is lower in regions with a greater representation of women in local-level politics in Europe."

(Virginia Tech. "Study finds less corruption in countries where more women are in government." ScienceDaily. ScienceDaily, 15 June 2018.)

The rupture of the masculinity-male and femininity-female associations

"Together, these findings suggest that gender stereotypes and self-attributions are changing in adolescents. Furthermore, our results can be considered to be an empirical confirmation of the rupture of the masculinity-male and femininity-female associations."

(Martínez-Marín, María Dolores, and Carmen Martínez. "Negative and Positive Attributes of Gender Stereotypes and Gender Self-Attributions: A Study with Spanish Adolescents." Child Indicators Research (2018): 1-21.)

Gender differences in psychopathology are quantitavie rather than qualitative, and related to brain masculinization/defeminization and acute testosterone levels

"Subtle gender differences in cognition arise due to the action of sex hormones during brain development, and are shaped by social influences [1-3]. Sex hormones also have immediate and reversible effects on cognition [4-6]. Women and men differ in specific measures of visuospatial and verbal ability, memory, and processing of emotional information [7,8].
The sexes also differ with respect to vulnerability to specific classes of psychopathology. For example, depressive and anxiety disorders are more prevalent in women, while autism, attention deficit hyperactivity disorder (ADHD) and Tourette Syndrome (TS) are more frequently observed in men [2,3]. Gender differences in psychopathology are most certainly a result of interactions between environmental factors and brain sexual dimorphisms. However, neuropsychiatric disorders also are often strongly influenced by genetic factors [9-11].
(...)
In sum, the present results point to complex interactions between gender and familial factors in determining premorbid characteristics, age of first psychotic episode, symptom severity, social functioning, and ultimate diagnosis. We propose that these gender differences may be related to quantitative variation in masculinization/defeminization of brain and cognition, as well as from acute effects of circulating estrogens and testosterone."

(Castro, Lina Díaz, Kurt Leroy Hoffman, Maria de Lourdes Nieto-García, Miriam Arroyo Belmonte, Hector Cabello-Rangel, Miguel Ángel Herrera-Estrella, Mariana Chávez-Cervantes, and Carlos Luis Aviña-Cervantes. "Gender Differences within the Psychosis Spectrum." Neuropsychiatry (London) 8, no. 4 (2018): 1186-1195.)

Ano-genital distance reflects prenatal androgen levels during early gestation, but not thereafter

"Our results suggest that AGD (Ano-Genital Distance) in humans, like animals, is fixed in early gestation (likely during the hypothesized MPW [masculinization programming window]) and is unaffected by androgen levels thereafter. Thus, AGD can serve as a biomarker of in utero androgen action during early gestation (likely 8–14 weeks) in humans."

(Jain, Viral G., Vaibhav Goyal, Vikas Chowdhary, Namita Swarup, Ravinder J. Singh, Arbinder Singal, and Prem Shekhawat. "Anogenital distance is determined during early gestation in humans." Human Reproduction (2018).)

Women more concerned about 'exploiting' social ties than men

"A new study reveals that it is not only exclusion by men, but also self-imposed barriers including hesitation and gendered modesty that prevent women from networking as effectively as their male counterparts. The research revealed that women's tendencies to harbor moral concerns about 'exploiting' social ties causes them to under-benefit from networking activities."

(SAGE. "Women build less effective professional networks than men as they underestimate self-worth." ScienceDaily. ScienceDaily, 15 November 2018.)

Men remember pain differently (causing them to be more sensitive to repeated pain) than women

"We believe that the mice and the men were anticipating [pain trigger] and, for the males, the stress of that anticipation caused greater pain sensitivity," says Mogil. "There was some reason to expect that we would see increased sensitivity to pain on the second day, but there was no reason to expect it would be specific to males. That came as a complete surprise."

(McGill University. "Men and women remember pain differently: Strength of finding confirmed by replication of results in mice and men." ScienceDaily. ScienceDaily, 10 January 2019. )

Facial masculinity not asscoiated with immunocompetence

"[W]e measured immunocompetence via heterozygosity at the major histocompatibility complex (MHC), a widely-used genetic marker of immunity. We show that, while height is positively correlated with MHC heterozygosity, facial masculinity is not. Thus, facial masculinity does not reflect immunocompetence measured by MHC heterozygosity in humans."

(Zaidi, Arslan A., Julie D. White, Brooke C. Mattern, Corey R. Liebowitz, David A. Puts, Peter Claes, and Mark D. Shriver. "Facial masculinity does not appear to be a condition-dependent male ornament and does not reflect MHC heterozygosity in humans." Proceedings of the National Academy of Sciences (2019): 201808659.)

Entrepreneurs like competition for the competition, not for winning or for personal development

"Referring to Isreal M. Kirzner (1973) and Schumpeter (1934), who emphasized the competitive nature of entrepreneurship, this study investigates whether potential and revealed entrepreneurs are more likely to seek competition than non-entrepreneurs. We provide a conceptual framework that links entrepreneurship to three facets of individual competitiveness drawn from economic, entrepreneurship, and psychological research: a desire to win, striving for personal development, and an enjoyment of competition. Following economic research linking competitive behavior in experiments to career choices, we conduct a lab-in-the-field study and demonstrate that entrepreneurs are more likely to enter competitions than non-entrepreneurs. Accounting for individual desires to win and mastery-related achievement motivations, our results indicate that entrepreneurs tend to enter competition for the sake of competition itself rather than for the prospect of winning it or personal development. Our results suggest that enjoyment of competition might be an additional factor driving entrepreneurs’ market entry decisions beyond well-known factors like overconfidence and risk-taking."

(Urbig, Diemo, Werner Bönte, Vivien D. Procher, and Sandro Lombardo. "Entrepreneurs embrace competition: evidence from a lab-in-the-field study." Small Business Economics (2019): 1-22.)

Females with specific genotype resemble males in Autism Quotient-Imagination subscale

"The extreme male brain theory of autism posits that its male bias is mediated by exaggeration of male-biased sex differences inthe expression of autism-associated traits found in typical populations. The theory is supported by extensive phenotypicevidence, but no genes have yet been described with properties that fit its predictions. The autophagy-associated gene AMBRA1 represents one of the top genome-wide “hits” in recent GWAS studies of schizophrenia, shows sex-differential expression, and has been linked with autism risk and traits in humans and mice, especially or exclusively among females. Wegenotyped the AMBRA1 autism-risk SNP in a population of typical humans who were scored for the dimensional expressionof autistic and schizotypal traits. Females, but not males, homozygous for the GG genotype showed a significant increase inscore for the single trait, the Autism Quotient-Imagination subscale, that exhibits a strong, significant male bias in typicalpopulations. As such, females with this genotype resembled males for this highly sexually dimorphic, autism-associated phenotype. These findings support the extreme male brain hypothesis and indicate that sex-specific genetic effects canmediate aspects of risk for autism."

(CRESPI, Bernard, et al. AMBRA1, Autophagy, and the Extreme Male Brain Theory of Autism. Autism Research and Treatment, 2019, 2019.)

Higher adult androgen exposure associated with higher handgrip strength and less emotionality

"2D:4D ratios and handgrip strength tests are two protocols that indirectly measure androgen exposure prenatally and in adulthood respectively. (...) Athletes who scored higher on the handgrip strength test showed lower levels of emotionality."

(BOURKE, Colm. The Characteristics of Successful Student Athletes. 2019. PhD Thesis. University of Louisiana at Monroe.)

Unethical behavior associated with higher facial width-to-height ratio in male and female athletes

"Past research has emphasized the role of facial structures in predicting social behavior. In particular the facial width-to-height ratio (fWHR) was found to be a reliable predictor for antisocial and unethical behavior. The current study was aimed at examining this association in the field of sports: FWHRs of 146 doping sanctioned athletes in athletics (37 male/38 female) and weightlifting (44 male/27 female) were compared to the fWHRs of randomly chosen non-doping sanctioned athletes of the Top Ten at the World Championship 2017 and Olympic Games 2016 in both sports (146 athletes). The results showed that doping sanctioned athletes due to the use of anabolic steroids had larger fWHRs than non-doping sanctioned athletes. However, doping sanctioned athletes due to other doping rule violations than the use of anabolic steroids, did not show this effect. The study provides empirical evidence for the relation between fWHR and unethical behavior in a real-world setting and contributes to the discussion about fWHR’s biological origin, emphasizing the role of anabolic steroids. A mutual interaction between fWHR and doping behavior is discussed, at which a larger fWHR might signify a higher tendency to behave unethically, whereas the consequential intake of anabolic steroids might also shape individuals’ faces."

(Krenn, B., and C. Buehler. "Facial features and unethical behavior-Doped athletes show higher facial width-to-height ratios than non-doping sanctioned athletes." PloS one 14.10 (2019): e0224472-e0224472.)

Cognitive rigidity associated with extremist attitudes

"Research into the roots of ideological extremism has traditionally focused on the social, economic, and demographic factors that make people vulnerable to adopting hostile attitudes toward outgroups. However, there is insufficient empirical work on individual differences in implicit cognition and information processing styles that amplify an individual’s susceptibility to endorsing violence to protect an ideological cause or group. Here we present original evidence that objectively assessed cognitive inflexibility predicts extremist attitudes, including a willingness to harm others, and sacrifice one’s life for the group. Across two samples (N = 1,047) from the United Kingdom and United States, structural equation models demonstrated that cognitive inflexibility predicted endorsement of violence to protect the national ingroup, which in turn predicted a willingness to die for the group. These statistical models accounted for an average of 31.4% of the variance in willingness to die for the group, after accounting for demographic variables. Furthermore, cognitive inflexibility was related to greater confidence in the decision to sacrifice one’s life in an ingroup trolley problem scenario. Analysis of participants’ performance on the cognitive tasks revealed that cognitive rigidity – distinctly from other aspects of cognition – was specifically implicated as a cognitive antecedent of extremist attitudes. Implications for the study of radicalization and identity fusion through a neurocognitive lens are discussed."

(Zmigrod, Leor, Peter Jason Rentfrow, and Trevor W. Robbins. "Cognitive inflexibility predicts extremist attitudes." Frontiers in psychology 10 (2019): 989.)

More feminine gender identity associated with more ethical behavior (also among men)

"This study shows that gender identity affects ethical intentions. We investigate the intention to purchase ethical products through a survey study among young consumers in Italy. Measures of planned behavior, internal ethics, self‐identity, and moral harm, together with proxies for individual gender identities of femininity and masculinity are included in our model of intention to purchase ethically. Results show that femininity significantly increases ethical intent, whereas masculinity has an opposite effect. These findings are robust to gender. In fact, the relations of femininity and masculinity on the intention to consume ethical products hold when the subsamples of males and females are considered."

(Pinna, Mariella. "Do gender identities of femininity and masculinity affect the intention to buy ethical products?." Psychology & Marketing.)

Autism associated with facial femininity in men, and facial masculinity in women

"In the present study, we conducted two experiments to examine facial masculinity/femininity in 151 neurotypical adults selected for either low, mid‐range, or high levels of autistic traits. In the first experiment, their three‐dimensional facial photographs were subjectively rated by 41 raters for masculinity/femininity and were objectively analysed. In the second experiment, we generated 6‐face composite images, which were rated by another 36 raters. Across both experiments, findings were consistent for ratings of photographs and composite images. For females, a linear relationship was observed where femininity ratings decreased as a function of higher levels of autistic traits. For males, we found a U‐shaped function where males with mid‐range levels of traits were rated lowest on masculinity. Objective facial analyses revealed that higher levels of autistic traits were associated with less feminine facial structures in females and less masculine structures in males. These results suggest sex‐specific relationships between autistic traits and facial masculinity/femininity."

(Tan, Diana Weiting, Murray T. Maybery, Louise Ewing, Jia‐Xin Tay, Peter R. Eastwood, and Andrew JO Whitehouse. "Sex‐specific variation in facial masculinity/femininity associated with autistic traits in the general population." British Journal of Psychology (2019).)

Women find artificially masculinized men more attractive

(Clarkson, Tessa R., Morgan J. Sidari, Rosanna Sains, Meredith Alexander, Melissa Harrison, Valeriya Mefodeva, Samuel Pearson, Anthony J. Lee, and Barnaby JW Dixson. "A multivariate analysis of women's mating strategies and sexual selection on men's facial morphology." Royal Society Open Science 7, no. 1 (2020): 191209.)

Women slower on mental rotation test, but with equal results; men and women approach spatial tasks differently

"Dr Toth sums up the results: "So males are better than females? Well no, actually. Our study found that there is no male advantage in mental rotation abilities. By lengthening the time allowed to complete the test, the male performance advantage diminished entirely suggesting that the so-called sex difference in mental rotation is simply not there or may be explained by other factors."

The research published in Nature Scientific Reports also found for the first time that both males and females frequently employed different gaze strategies during the cognitive tests to get to the correct answer. In other words, men and women approach the task in a different way to get the same result.

The research paper is entitled: 'Investigating sex differences, cognitive effort, strategy, and performance on a computerised version of the mental rotations test via eye-tracking.'"

(University of Limerick. "The sexes have equal spatial cognition skills: Men and women approach the task differently but get the same result." ScienceDaily. ScienceDaily, 27 January 2020)

Testosterone and Cortisol, the Secular Trend, and the Decline of Forethought and Individuality in Society and Religion

Below an article by James Michael Howard which I copied in its entirety, because I could only find it as a response to another article and would not want to lose it. All rights go to the original author of course, whom I hope does not mind my copying it here.
James Michael Howard's website can be found here: http://www.anthropogeny.com/

Brief

Individuals of higher testosterone and lower cortisol have a reproductive advantage. These individuals are aggressive, sexy, do not control their impulses easily, have less ability to anticipate consequences and smaller prefrontal lobes, and form into groups. Because of their reproductive advantage the population will change and the characteristics of these individuals will increase accordingly within the population.

Another aspect of too much testosterone is increased vulnerability to infections. High testosterone populations prior to the advent of anti-microbial agents and medical care were at increased risk of infections, and pandemics occurred. These plagues of Europe removed most of the people of high testosterone. The surviving people of lower testosterone produced the intellectual accomplishments known as the "Renaissance." Since the plagues differed in effect and timing in the "East," there was not as large a removal of people of high testosterone; the Renaissance was limited to Europe.

Testosterone and Cortisol, the Secular Trend, and the Decline of Forethought and Individuality in Society and Religion

by James Michael Howard

"It is my hypothesis that civilizations have ascended and declined as a consequence of the degree of development of the prefrontal lobes of the brains of the majority of citizens. Development of the prefrontal lobes is a consequence of growth and development of the individual. A change in growth and development of the individuals of a population over time is a "secular trend." I suggest the secular trend results in increases, followed by reductions, in size and function of the prefrontal lobes of many individuals within a population as the population evolves.

The secular trend is the increase in size and earlier puberty in children. The secular trend in the United States is real and robust and is likely "an acceleration of maturation" (Archives of Pediatric and Adolescent Medicine. 2000; 154: 155). Many think the secular trend results from increased nutrition, especially increased fat in the diet. I suggest the trend results from differential reproduction of types of individuals; increased nutrition, mainly increased calories, simply accelerates the process. Increased nutrition provides a favorable "feed and breed" situation. Increased nutrition increases the advantages of a faster breeding group over a slower breeding group. I think the trend represents the increase in percentage of individuals who produce different levels of hormones that directly, and positively, affect their rate of reproduction. Individuals of higher testosterone and lower cortisol have a reproductive advantage in our society.

Testosterone increases sex drive and aggression in men and women. Given time, individuals of higher testosterone will reproduce faster than those of less testosterone. This trend will increase the percentage of sexier, more aggressive individuals. The population will change and the characteristics of these individuals will increase accordingly within the population.

Cortisol is the "stress hormone." When cortisol increases in response to a stimulus, cortisol reduces the response to that stimulus. Behaviors that stimulate cortisol do not occur often. Women who produce less cortisol engage in sexual intercourse at a younger age and produce less cortisol in response to stress later in life (Psychoneuroendocrinology 2002; 27: 933). Women of low cortisol and high testosterone "may" engage in sexual activity much earlier and with greater frequency than those of higher cortisol and lower testosterone.

Given time, these women and their offspring will increase in percentage within a population and affect the characteristics of that population.
They are sexy and fearless.

Testosterone affects both the brain and body. From birth until puberty, the brain and body compete for growth and development. Early in growth and development, the brain, as a whole, dominates this competition. As the brain begins to finalize its growth, its ability to compete for testosterone begins to decrease compared to the body. At this time, the part of the brain that controls sex drive (lower brain) is complete, but the final part of brain development (upper brain) is not complete. (This competition of brain and body development is how the onset of puberty is delayed until the brain is almost complete.) The part of the brain that controls sex drive contains more "receptors" for testosterone than the upper brain. As puberty approaches, this combination of competition for testosterone from the lower brain and the body adversely affect final development of the upper brain, specially the prefrontal lobes. In an individual of higher testosterone, the increased testosterone positively affects the lower brain during this competition. Puberty occurs early, the final part of growth and development of the prefrontal lobes is adversely affected and, in a person of low cortisol, sexual behavior starts early. The combination of high testosterone and low cortisol increases the use of testosterone for the behavior controlled by the lower brain, that is, puberty and sexual activity. These individuals should exhibit reduced ability to control their behavior because of high testosterone, low cortisol, and reduced development of their prefrontal lobes. Outside of their group, they exhibit impulse control problems.

Individuals of high testosterone and low cortisol present real problems for society. High testosterone is connected with violent, negative behaviors. "The matched analysis further substantiated the association between testosterone secretion and learning disabilities." (Physiol Behav 1993; 53: 583). "The group of rapists who were judged to be most violent had a significantly higher mean plasma testosterone level than normals, child molesters, and other rapists in this study." (Psychosom Med 1976; 38: 257). "In the housing unit where peer ratings were most reliable, inmates rated as tougher by their peers were higher in testosterone." (Psychosom Med 1987 49: 174). "Decreased cortisol levels appear to be most strongly associated with antisocial girls who do not have other psychiatric disorders." (Arch Gen Psychiatry. 2001; 58: 297). "Low cortisol levels were associated with persistence and early onset of aggression, particularly when measures of cortisol concentrations were pooled. Boys with low cortisol concentrations at both time points exhibited triple the number of aggressive symptoms and were named as most aggressive by peers 3 times as often as boys who had higher cortisol concentrations at either sampling time." (Arch Gen Psychiatry 2000; 57: 38). Most importantly to this treatise is the finding that prefrontal gray matter volume is reduced in a group of people who exhibit "antisocial personality disorder (APD)" who otherwise "do not have discernible brain trauma." "The APD group showed an 11.0% reduction in prefrontal gray matter volume in the absence of ostensible brain lesions and reduced autonomic activity during the stressor. These deficits predicted group membership independent of psychosocial risk factors." (Arch Gen Psychiatry 2000; 57: 119). These individuals are aggressive, sexy, do not control their impulses easily, and form into groups.

Mathematics, science, language, and law depend upon real consequences. "Culture" and "religion" depend upon hypothetical consequences. "Forethought," or hypothesis formation, is dependent upon development of the prefrontal lobes of the brain. Hypothesis formation consists of two simple questions: "If this happens, what will happen?" and its immediate accompaniment, "If I do this, what will happen?" I specifically stated that religion utilizes "hypothetical consequences" to enforce the hypothesis: "If I do this, what will happen?" Whether one believes in a God of the present or of the future, the consequences that result from transgressions of doctrine remain abstract. One has to
wonder (hypothesize) when consequences will happen, soon or upon one's death. I have suggested that the prefrontal lobe declines within civilizations. The last quotation of the paragraph, above, I think, supports my hypothesis and adds one very significant finding. The prefrontal lobes of the subjects of the study were actually reduced in size in "antisocial personality disorder." This results in loss of individuality: "These deficits predicted group membership independent of psychosocial risk factors." Reductions in the prefrontal lobes result in loss of ability to anticipate consequences and also increase group membership. This translates to thinking with the lower brain, emotional thinking, and groups of emotional thinkers. Religion relies on some combination of abstract thinking or emotional thinking. The percentages of individuals who utilize either abstract thinking or emotional thinking may produce the different religions and denominations. I suggest some religions rely on emotional thinking because it exerts more control over their flocks. These religions contain groups of individuals of higher testosterone and lower cortisol who may be moved to commit acts that are in direct contrast to the founding religion. Given time, the secular trend will produce this phenomenon. There are other, natural circumstances that may accelerate this phenomenon. Though this occurs in the "West," there are reasons why religions of the "East" contain more "zealot" sects. "Western Civilization" and its religions may differ because of a biological accident.

Again, I think testosterone increases and cortisol decreases in all civilizations. I think the secular trend is a phenomenon of all human populations that have succeeded in producing civilizations. Fortuitously for Europe and the West, another, consequential, negative aspect of too much testosterone is increased vulnerability to infections. Testosterone has been connected with increases in all types of infectious agents.

Experimentally, testosterone has been used to prove this connection. Therefore, populations prior to the advent of anti-microbial agents and medical care were at increased risk of infections. Where infectious agents gained entry into high testosterone populations, pandemics occurred. These plagues of Europe accomplished something "beneficial," that is, the plagues removed most of the people of high testosterone. The surviving people of lower testosterone produced the intellectual accomplishments known as the "Renaissance." Since the plagues differed in effect and timing in the "East," there was not as large a removal of people of high testosterone; the Renaissance was limited to Europe.

"Western civilization" is the result of the "good luck" of having plagues remove the majority of people of high testosterone. Therefore, fewer sects have evolved out of the paramount religions in the West. It is beginning to happen here; there were / are religious atrocities in Western religions, but the atrocities of Eastern religions far surpass those of the West at this time.

*Copyright: 2002, James Michael Howard, Fayetteville, Arkansas, U.S.A. This work is derived from three of my papers: "Hormones in Mammalian Evolution," Rivista di Biologia / Biology Forum 2001; 94: 177-184; "Androgens in Human Evolution. A New Explanation of Human Evolution," Rivista di Biologia / Biology Forum 2001; 94: 345-362, and "Mitochondrial Eve, Y Chromosome Adam,Testosterone, and Human Evolution," Rivista di Biologia / Biology Forum 2002; 95: 319-326.

Competing interests:  None declared

Competing interests: No competing interests"

(source: http://www.bmj.com/rapid-response/2011/10/29/actually-it-more-testosterone)

Genetics and their influence on behavior, brain and society

All individual psychological differences are moderately to substantially heritable

"Psychological researchers typically distinguish five major domains of individual differences in human behavior: cognitive abilities, personality, social attitudes, psychological interests, and psychopathology. [...] In this article we [...] review behavioral genetic findings in all five domains. We conclude that there is now strong evidence that virtually all individual psychological differences, when reliably measured, are moderately to substantially heritable."

(Bouchard, Thomas J., and Matt McGue. "Genetic and environmental influences on human psychological differences." Journal of neurobiology 54.1 (2003): 4-45.)

DNA defines number of androgen receptors in brain

"Many factors influence how androgens impact brain functioning. Of course, some of these factors involve the actual prevalence of androgens in the brain during crucial periods of development (Kimura, 1992; Nordeen, Nordeen, Sengelaub, & Arnold, 1985). Another factor involves so-called androgen receptors (ARs). Without these receptors, the prevalence of androgens is largely inconsequential (La Spada, Wilson, Lubahn, Harding, & Fischbeck, 1991; Sato et al., 2004). The number of ARs is in turn determined by what are known as CAG repeats in the androgen receptor (AR) gene (located on the X chromosome, of which males only have one). The more CAG repeats on the X chromosome, the fewer the number of ARs an individual will have (Allen, Zoghbi, Moseley, Rosenblatt, & Belmont, 1992; Giovannucci et al., 1997). The number of CAG repeats in the AR determining gene is likely to play an important role in the ability of androgens to influence criminality and related behaviors (such as psychopathy).
Recent evidence pertaining to the above reasoning has been encouraging. A study conducted in India involving over five hundred men, roughly half of whom were convicted of rape. Evidence from
this study revealed that the rapists had significantly shorter CAG repeats in their AR genes than control males (Rajender et al., 2008). Also, a Chinese study found that the length of the AR gene repeats was significantly shorter among violent criminals than among the non-criminal males (Cheng, Hong, Liao, & Tsai, 2006). Findings from both of these reports suggest that male criminals, particularly those with assaultive tendencies, have unusually short CAG repeats in their AR genes relative to males in general. Furthermore, research has shown that the number of CAG repeats in AR genes is inversely associated with childhood conduct disorders and other forms of externalizing behavior among boys (Aluja, García, Blanch, & Fibla, 2011; Comings, Chen, Wu, & Muhleman, 1999)."

(Ellis, Lee, and Anthony W. Hoskin. "The evolutionary neuroandrogenic theory of criminal behavior expanded." Aggression and violent behavior 24 (2015): 61-74.)

HOX genes and influence on gonad, fingers and digit ratios

"The differentiation of gonads, fingers, and toes is influenced by HOXA and HOXD genes. Therefore variation in the development of the gonads, and their fetal products such as testosterone, may be reflected in the morphology of the fingers and toes. One trait, the relative length of the second and fourth digits (2D:4D), shows sex differences (lower values in males) which are determined early, and 2D:4D has been found to correlate with fetal growth, sperm counts, family size, autism, myocardial infarction, and breast cancer. HOX genes are highly conserved in mammals and they influence the differentiation of all the fingers and toes. We suggest that (a) 2D:4D and other ratios of finger and toe length show sex differences throughout the mammals including humans and mice, (b) finger and toe ratios correlate with sex determination, the fetal production of sex steroids, and fetal programming of disease, and (c) HOX gene influences on sex determination, the morphogenesis of the urinogenital system, fertility, haematopoiesis, and breast cancer suggests that finger and toe ratios in humans and mice may correlate with many sex dependent diseases."

(Manning, J. T., M. Callow, and P. E. Bundred. "Finger and toe ratios in humans and mice: implications for the aetiology of diseases influenced by HOX genes." Medical Hypotheses 60.3 (2003): 340-343.)

"[I]n 1984 the psychologist Sarnoff Mednick tapped into a Danish database of more than 14,000 adopted children, some of whom had been convicted of crimes. Mednick found that more than twice as many offenders convicted of property crimes, such as breaking and entering, had a biological father who was a criminal, compared with those who had an adopted criminal father; the proportion was even higher for repeat offenders. He concluded that criminal parents passed on ‘some factor’ to their biological children that made it likelier for them to become criminals, but noted that the correlation did not hold true when looking at violent crimes such as murder or assault.
Others have studied twins to look for hereditary similarities. Scientists who have analysed Denmark’s twin records have found a stronger correlation in crime between identical twins than between non-identical ones. That’s not to say that born criminals exist, according to Irving Gottesman, a psychologist at the University of Virginia who studied the Danish twin records; but heredity seemed to play a role in setting up the odds.[...]
[I]n 2011 [Avshalom Caspi and Terrie Moffitt of Duke University in North Carolina] published a finding (one among the hundreds they have produced over the years) that psychological assessments of self-control in children as young as three can predict whether a child will become a criminal in his or her 30s. They were able to reach that conclusion only after compiling the data of more than 1,000 people who had been tracked from early childhood to adulthood.[...]
While one gene does not equal one behaviour, for instance, patterns in thousands of genes can interact with thousands of behaviours in a constantly changing human environment. One study of fruit flies bred for aggression found partial links to 80 different genes. It’s also become known that gene expression is not a one-way street: while genes might affect a person’s body or even behaviour, the person’s environment can affect genetic expression. In one of their studies undertaken in Dunedin, Moffit and her post-doctoral student Idan Shalev found that 10-year-olds who experienced violence showed the kind of wear and tear in their DNA normally associated with ageing. All this means that, while it’s possible that a particular gene deficiency might have something to do with violent behaviour, it’s ludicrous to say that it directly caused it.
The same is true of brain structure and function. In recent years, researchers have learned that just as the brain can set tendencies, experiences can influence how they’re expressed.[...]
Minus the clutter, if you look at the totality of peer-reviewed studies of the past several years, it’s hard not to come to the conclusion that biology plays some role in criminal behaviour, impossible to quantify. The new science of epigenetics proposes an interaction between environment and heredity, in which environmental factors (such as childhood abuse) can affect the expression of genes. In other words, the nature-nurture division that scientists have been arguing about for more than a century is narrowing, and might someday disappear. Genes and brain structure do not represent a simple on-off switch that determines a person’s behaviour but, as some studies show, they can indicate a vulnerability.[...]
[Adrian Raine, professor of psychology, psychiatry and criminology at the University of Pennsylvania] has been studying brain scans for decades, and he has come up with a kind of grand unified theory of violence. He describes it with the phrase ‘from genes to brain to antisocial behaviour’. Certain gene abnormalities can lead to structural brain abnormalities that lead to emotional and cognitive abnormalities (such as poor impulse control) that can lead to anti-social behaviour. At the same time, he writes, early life experiences – including maternal neglect, poor nutrition, or being surrounded by gang violence – can feed into the cycle."

(source: "The inheritance of crime", by Douglas Starr, professor of journalism at Boston University, where he is co-director of the Center for Science and Medical Journalism. published on Aeon, retrieved 26-7-2016)

"Your genes may influence how sensitive you are to emotional information, according to new research by a UBC neuroscientist. [...] The gene in question is ADRA2b, which influences the neurotransmitter norepinephrine. [...] "We thought, from our previous research, that people with the deletion variant would probably show this emotionally enhanced vividness, and they did more than we would even have predicted, [...]."

(source: How your brain reacts to emotional information is influenced by your genes)

"Scientists have confirmed that variations in [the GABRB3] gene [... are] linked to differences in empathy levels in the general population."

(source: Study confirms a gene linked to Asperger Syndrome and empathy)

"Intellectual faculties are the sum of many factors, the majority of which are genetic and inherited from parents." (Dr. Sébastien Jacquemont, geneticist, clinical researcher at CHU Sainte-Justine and professor at the University of Montreal)

(source: Twenty-five-point drop in IQ caused by lack of gene copy, accessed 2016-01-28)

"In this study, the Japanese researchers determined that ​PX-RICS is most likely the gene responsible for autism-like symptoms in Jacobsen syndrome. To do this, they performed several well-established tests that measure common autism symptoms -- anti-social behavior, repetitive activities and inflexible adherence to routines. As compared to normal mice, mice lacking PX-RICS spent less time on social activities (e.g., nose-to-nose sniffing and huddling) and were more apathetic or avoidant when approached by a stimulator mouse. PX-RICS-deficient mice also spent more than twice as much time on repetitive behaviors such as self-grooming and digging than normal mice. In addition, mice lacking PX-RICS more closely adhered to a previously established habit and were less able to adapt their behavior in novel situations."

(Mouse model yields possible treatment for autism-like symptoms in rare disease, Sciencedaily, retrieved 17-3-2016)

"We were surprised by certain behaviors that showed a genetic influence, such as religiosity [and] social attitudes," said Nancy Segal, an evolutionary psychologist at California State University, Fullerton, who was part of the study for nine years. "Those surprised us, because we thought those certainly must come from the family [environment]," Segal told Live Science. [...]
The Minnesota researchers found that about 70 percent of IQ variation across the twin population was due to genetic differences among people, and 30 percent was due to environmental differences. The finding received both praise and criticism, but an updated study in 2009 containing new sets of twins found a similar correlation between genetics and IQ.
Moreover, a study in 1990 found that genetics account for 50 percent of the religiosity among the population — in other words, both identical twins raised apart were more likely to be religious or to be not religious, compared with unrelated individuals."

(Source: LiveScience, retrieved 30-5-2016)

(source: "Insights From Identical Twins", http://learn.genetics.utah.edu/content/epigenetics/twins/, retrieved 30-5-2016)

Nature or Nurture? The Study of Twins | Nancy Segal and Stefan Molyneux

"[T]hey looked at the IQ scores of mothers who had given away their children for adoption. So they had the IQ score of the biological mom, the adopted away kid, and the adoptive parents of that kid. And you know who was more alike? The biological kid and the biological mom who were not together, as compared to the adoptive mom who had raised the adoptive child."

(Dr. Nancy L. Segal, B.A. degree in psychology (with distinction) and English literature from Boston University (1973), and M.A. (1974) and Ph.D. (1982) degrees in Social Sciences and Behavioral Sciences from the University of Chicago. She is currently Professor of Psychology at California State University, Fullerton (CSUF) and Director of the Twin Studies Center which she founded in 1991.)
(source: Youtube interview "Nature or Nurture? The Study of Twins | Nancy Segal and Stefan Molyneux", 36min18s)

More arborized cortical neurons (with more dentritic branches) make friendlier, more social brains

"Scientists investigated Williams syndrome or WS, a rare genetic condition caused by deletion of one copy of 25 contiguous genes on chromosome 7, out of an estimated 30,000 genes in the brain. [...] WS results in a host of medical problems as well as a specific heart defect. [...] Neurologically, [persons with the deletion] have developmental delays, with severe spatial deficits, yet relative strengths in language use and face processing.
'An interesting aspect is the typical hyper-social predisposition,' said study co-author Ursula Bellugi, EdD, director of the cognitive neuroscience lab at Salk and an adjunct professor at UC San Diego who has studied WS for years. 'Persons with the WS deletion tend to be overly friendly, overly trusting, drawn to strangers, yet anxious.' [...]
'I was fascinated on how a genetic defect, a tiny deletion in one of our chromosomes, could make us friendlier, more empathetic and more able to embrace our differences,' [co-senior study author Alysson] Muotri [PhD, associate professor of pediatrics and cellular and molecular medicine at UC San Diego School of Medicine], said. [...]
Cultured WS neurons have a distinct morphology. They are more arborized (treelike, with many dendritic branches) than neurons derived from typically developing individuals. "At the functional level, they make more synapses or connections to other neurons than what you would expect," said Muotri. "That might underlie the WS super-social aspect and their gregarious human brain, giving insights into autism and other disorders that affect the social brain." [...]
'One striking observation was that [the] cortical neurons in WS individuals are more complex than controls (typically developing children of same age). The morphological alterations that presumably appeared during WS gestation are kept postnatally,' [said Katerina Semendeferi, PhD, co-senior author and professor at UC San Diego Department of Anthropology.]"

(source: "Neurodevelopmental model of Williams syndrome offers insight into human social brain", SienceDaily, August 10 2016)