All human life stems from the reality of, and the difference between, men and women.

~ Nina Power – What do Men Want? Masculinity and its Discontents

In this series of posts about the boys and men crisis described by Richard Reeves (Of Boys and Men), I have detailed eleven problems and conditions faced by men and boys and fourteen solutions offered by Reeves to address these problems. One of Reeves’s most important contributions is “naming” and elucidating the “twelfth” problem of how the political Left and Right are unhelpful and wrong in their narratives about the crisis. He critiques the views about biological differences on both sides of the political spectrum. But it is the political Left that is most problematic in this arena.

Progressives Often Deny the Neuroscience of Sex Differences

As I said in Part 3.1 (What the Political Left Gets Wrong About Boys and Men) many progressives deny the neuroscience of sex differences. “For many progressives, it is now axiomatic that sex differences or behaviors are wholly the results of socialization,” Reeves laments. (Acknowledging biological differences between the sexes is not very “woke.”)

As part of its mission, Mating Straight Talk has criticized this “standard social science model (SSSM)”* and has described research of evolutionary psychology that incorporates natural selection and sexual selection in understanding the co-evolution of culture and biological adaptation.

Let’s Review Biological Sex Differences in the Next Two Posts

Because the political Left is so resistant to acknowledging biological sex differences, Parts 5.1 and 5.2 of this series will review some differences supported by research.

First — the Caveats About Biological Differences

The idea that there is a natural basis for sex difference is, however, politically charged. So, I’d better get the caveats in right away. ~ Richard Reeves

Reeves anticipated the degree of pushback he would get for acknowledging and researching biological sex differences. He went out of his way to soften the message with the caveats listed below. All these caveats are addressed and accepted by the discipline of evolutionary psychology and mate selection science (and in the website pages and blogs of Mating Straight Talk), except for Caveat #3.

Caveats Do Not Dilute Power of Average Differences

These caveats do not dilute the power of average differences between men and women that affect our relationships and culture. We can confirm the basic “rules” of our biology represented by the middle two-thirds of the bell curve while being curious about and honoring the exceptions to the rule.

Caveat #1: Differences are dimorphic but overlapping – rather than binary.

While certain traits are more associated with one sex than the other, the distributions overlap, especially among adults. For every brain measure that showed significant sex differences, there was always an overlap.

For example, the typical male is more willing to take risks than the typical female (especially in adolescence). But some women are more risk-taking than some men. A large majority of the most aggressive people are male, but the differences in aggressiveness in the general population are much smaller.

Caveat #2: Sex differences can be magnified by culture.

The immediate environment and broader culture affect how these biological differences develop and are expressed. Sex differences can be magnified or muted by culture. Culture and biology do not develop separately from each other. They co-evolve.

“It is hard to find a responsible scientist who is either an outright determinist or an outright denier on the question of biology,” says Reeves.

But Reeves identified outright deniers in an earlier section of the book. Denial of biological differences was, for Reeves, a significant motivation for writing this book.

Neuroscientist Lou Ann Brizendine (The Female Brain and The Male Brain) writes: “Biology does represent the foundation of our personalities and behavioral tendencies. If, in the name of free will and political correctness, we try to deny the influence of biology on the brain, we begin fighting our own nature.”

Yet, as British neurobiologist Gina Rippon explains, “it is perfectly possible to believe in biology without mindlessly assuming that human nature is fixed and unchangeable or that culture and environment are irrelevant.”

Caveat #3: Sex Differences have a modest impact on our day-to-day lives.

Reeves claims sex differences typically have a modest impact on day-to-day lives in the twenty-first century. He says there is more room for other drivers of behavior. Reeves supports a three-part model of human behavior: a combination of nature (our instincts based on biology), nurture (the instructions we get from our surrounding culture), and agency (our personal initiative.) This model is an excellent starting point for understanding our behavior. No doubt, much of the drama of human life stems from the tension between these forces.

Disagreement About the Impact of Sex Differences

I argue two things related to this caveat: 1) the impact of sex differences is more than “modest” in our daily lives, and 2) culture and personal agency are interdependent with sex differences, not separate from them.

To the first point: biological sex differences have a powerful impact on our current cultural milieu – on the tone of our near-ubiquitous conversations about gender identity and sexual preference. Sex differences are revealed and impact dozens of dating apps, dating websites, dating reality television shows, and relationship coaching. It is the water that flows in nearly all cinema and literature. The difference between the sexes frames conversations about “consent” in heterosexual relationships and fuels the search for an antidote to “toxic masculinity” – and ultimately, the recovery (or creation) of “noble” masculinity that provides much needed servant leadership.

Modest impact? Hardly. Whenever or wherever sexuality is involved (especially heterosexuality) – biological sex differences are salient; the impact on our daily lives is quite significant.

Caveat #4: Average sex differences do not justify the institutionalization of gender inequality.

“There is a fear that biology can be used to prove an intellectual foundation for sexism,” says Reeves. “This is well-founded given our history; it can be used to justify oppression.” Reeves does not elaborate on the historical data points of such oppression. But goes on to emphasize a thought not repeated often enough:

Denying science altogether is not useful. The rather boring truth is that masculine traits are more useful in some contexts and feminine ones in others, and neither set in intrinsically better than the other.

Reeves’s point about the institutionalization of gender inequality is well understood and accepted by credible researchers in sociology, anthropology, neuroscience, biology, and evolutionary psychology. There is no argument here, but the caveat apparently needs to be said, especially given the pernicious nature of our gender-related culture wars.

Caveat #5: Average differences between groups should not influence the view of individuals.

We should not view individuals by assumptions of aggregate difference. This caveat is obvious; it is not disputed among scientists who understand subject sampling, statistical analysis, and the range within the bell curve of individual differences.

Naturalistic and Moralistic Fallacies

Evolutionary psychology has directly addressed the problem of making assumptions about an individual based on data of aggregate difference. Because of general resistance to evolutionary psychology in some social sciences circles, the academic literature emphatically cautions against succumbing to two fallacies of reasoning.

The first is the naturalistic fallacy. This fallacy presumes that everything natural is necessarily good. That is a leap of logic not supported by evolutionary psychologists.

More problematic is the other fallacy lurking around the resistance to evolutionary psychology – the moralistic fallacy. The moralistic fallacy says what is good, or moral, ought to be true and is found in nature. This fallacy is more familiar to the political Left, such as “men and women ought to be given equal opportunities because women and men (in aggregate) can do everything equally well.”

Sex Differences in Brain Development

If, in the name of political correctness, we try to deny the influence of biology on the brain, we begin fighting our own nature. ~ Louann Brizendine (The Female Brain)

Boy’s Brains Develop More Slowly.

Boy’s brains develop more slowly, especially during the most critical years of secondary education. The parts of the brain associated with impulse control, planning, and future orientation are primarily in the prefrontal cortex, which matures about two years later in boys than in girls. As a result, almost one in four boys is categorized as having a “developmental disability,” according to a study in Pediatrics (2017).

Attention and Self-Regulation

The cerebellum reaches full size at age 11 for girls but not until age 15 for boys. The cerebellum has a modulating effect on emotional, cognitive, and regulatory capacities. The most significant difference between boys and girls related to attention and self-regulation occurs during middle adolescence.

Adolescent Male Brains Have More Accelerator and Less Brake

Adolescence is a period when it is harder to restrain ourselves. It is a battle between the sensation-seeking part of the brain (Go to the party! Forget school!) and the impulse-controlling part (I really need to study tonight). “It helps,” says Reeves, “to think of these as the accelerator and brake pedals in a car.” Boys have more acceleration and less braking power.

Adolescent Girls Have More Synapses and Connectivity

“In adolescence, on average, girls are more developed by about 2-3 years in terms of the peak of their brain synapses and their connectivity processes,” says Frances Jensen, chair of the department of neurology at the University of Pennsylvania’s School of Medicine. This is no surprise to most people who know 15-year-old boys and girls.

Gender Gap In Skills and Traits

The gender gap in developing skills and traits most important for academic success is the widest at precisely the time when students need to worry about their GPA, getting ready for tests, and staying out of trouble. According to a 2019 National Academies of Sciences, Engineering, and Medicine report, “sex differences in associations between brain development and puberty are relevant for understanding prominent gender disparities during adolescence.”

The Biggest Difference is When Development Occurs

“There are certainly some biological-based differences in male and female psychology that last beyond adolescence,” Reeves explains. “But by far, the biggest difference is not how female and male brains develop, but when.”

Nature and Nurture (Culture) on Sexual Psychological Difference

The real debate is not about whether biology matters, but how it does and when it does. ~ Richard Reeves

According to Reeves, culture determines how we manage, channel, and express many natural traits (see Caveat #2 above). As has been said, both nature and nurture determine how biological differences will manifest and express themselves.

Serotonin, Aggression, and Unstable Environment

For example, growing up in a stressful or unstable family environment appears to influence the capacity of the brain to metabolize serotonin. Serotonin helps to reduce aggressive behavior. If a boy or man does not metabolize serotonin effectively, their behavior may be more aggressive.

Boys with “Sensitive Genes” Do Worse When Fathers Leave

Significant research in epigenetics identifies how gene expression can sometimes be turned on or off. Reeves reports that boys with genes sensitive to the environment do worse when their biological fathers leave the household and benefit if their father stays or rejoins the family.

Harvard evolutionary psychologist Joseph Henrich argues that it makes the most sense to think of the co-evolution of nature and nurture. “Culture rewires our brains and alters our biology,” he says, “without altering the underlying genetic code.”

Marriage is a Testosterone Suppression System

Henrich says that marriage is a “testosterone suppression system.” Testosterone levels are highest among young single men, and those with higher testosterone are more likely to become fathers. But testosterone levels fall among men who settle down with a wife and children, and the drops are sharpest among men who do more childcare. “Human males have an evolved neuroendocrine architecture shaped to facilitate their role as fathers and caregivers as a key component to reproductive success,” says Henrich.

The Nice Guy – Bad Boy Trade-off

Falling testosterone levels mean that a caregiving “nice guy” (wanted and yet not wanted by many women) has less “bad-boy power” at the neuroendocrine level. Given the common problem of “hedonic adaptation”** or boredom inside a monogamous partnership, it is doubly hard for “nice” husbands and boyfriends to compete with fantasies about “bad boys” outside the pair bond. Luckily, one might say, it is good that women tend to turn down their (already lower) sexual interest when in monogamous partnerships.

No Wonder Married with Children Means Less Sex

Directing the energy required to raise children often has the practical effect of reducing female sexual desire. When you match that with lessened male testosterone, it is no surprise that many married couples with children have a diminished sex life. Lower testosterone and mutually reduced sex drive may not be a bad thing; it may be an evolutionary adaptation for successful caregiving and parenting.

Nature and Nurture Interdependence – Proximate or Ultimate Causation?

As outlined in my previous writing and summarized by experts in evolutionary psychology and sexual selection, the issue here is about identifying proximate causes for human (or animal) behavior versus ultimate causes. Proximate causes are influences from the current environment and culture. Ultimate causes are the result of thousands of years of human adaptation.

Survival and sexual reproduction operate almost entirely by ultimate causation. That is the starting point, the infrastructure, for any exception or adaptive readjustment that may come from the current environment or culture.

There Are Limits to Evolution as a Function of Culture

There is evidence of epigenetics — the effect of environmental factors on gene expression. Cultures do indeed change, and cultures can determine how some elements of masculinity and femininity are expressed.

But, as some anthropologists and evolutionary psychologists have said, there are limits to the evolution of human behavior as a function of culture. Humans are never going to grow wings and fly around the sky.

Can We Evolve Beyond Sex for Protection and Resources?

How quickly can we evolve from a “sex traded for protection and resources” (safety and security) paradigm? Perhaps we are doing that right now… but sexual desire operates with ancient hormonal roots and physiological signals of fertility. Don’t hold your breath for this evolutionary change. Biological differences between the sexes have been around for a long time.

*The Standard Social Science Model (SSSM) is a model of human development that assumes the mind was shaped primarily, if not entirely, by culture and social conditioning. SSSM is often associated with the concepts of “blank slate,” social constructivism, or cultural determinism that have dominated the social sciences throughout the 20th century (especially in the U.S.).

**Hedonic adaptation is the observed tendency of humans to quickly return to stable levels of happiness despite positive or adverse events. In a romantic context, it means that humans might “get used to” their partner and not sustain initial levels of excitement and passion over time.