Sex Differences, and the War Between Nature and Nurture

By William Gairdner
William Gairdner
William Gairdner
William Gairdner is a best-selling author living near Toronto. His latest book is "Beyond the Rhetoric" (2021). His website is
March 14, 2019 Updated: March 14, 2019

“Girls and boys are as different from the neck up as they are from the neck down.”

– Psychologist and author JoAnn Deak, in her speech“Taking the Mean Out of Teen

For more than 50 years, the standard social-science model has insisted that differences between the sexes—and therefore their different social outcomes—are learned from the environment (from nurture). But over the same period, science has revealed a large number of measurable sex differences that are rooted in the structure and function of the brain, and in biology (in nature).

Most Western democracies began as nature societies. They believed that both sexes would express their natural biological differences in the personal choices and outcomes of their lives. This kind of society calls for liberty and the free expression of natural differences under a rule of law that is the same for all.

But those same democracies slowly mutated into nurture societies, resting on the belief that all human beings are the same and, therefore, their differences must be socially constructed. Accordingly, they call for a regulatory war against all sorts of inequalities, and for differential laws imposing discriminatory policies against some groups of citizens in favor of others.

By providing fact-based evidence that a great many differences between the sexes are natural and hard-wired, however, scientists armed with high-tech machinery have been steering us into a renewed ideological war between nurture and nature, and therefore into a clash with our own public philosophy. The outcome of this war between hard-science nature and soft-science nurture is going to be interesting.

In no particular order, here is a brief overview of some measurable natural sex differences, all of which can be easily found by searching the internet for scientific papers on cognitive sex differences, male versus female sex differences, the psychology of sex differences, and so on.

Gendered Senses

Even while still in the womb, male and female babies behave differently, and moments after birth, they show different interests and intensities of reaction to the same objects, sounds, and tactile sensations.

As newborns, girls are more sensitive to sounds, smells, tastes, touch, voice, and musical nuances than boys. A girl’s sense of smell is anywhere from 200 to 1,000 times keener than a boy’s; sense of touch, twice as sensitive; and sense of hearing, two to four times keener than a boy’s. The eyes of baby girls are far more sensitive to the long-wavelength light spectrum than those of boys, and they can detect much lower concentrations of sweet, sour, bitter, and salty tastes than boys can, and have quite different taste preferences almost from birth.

A Baby’s Cry

This seems rather telling: Infant girls—but not infant boys—will easily distinguish a baby’s cry from other general sounds.

Boys and Objects

Although baby boys get as much affection and physical contact from their mothers as do girls, they nevertheless tend to prefer objects to people.

Girls and Language

All researchers report that girls tend to develop and process language, language fluency, and verbal memory earlier than do boys.  

Play Differences

Girls are less rule-bound, while boys are more so. Boys want rules telling them if they are winning or not, so they generally prefer rank-related play—a difference seen later in work as well as in play. Boys more vigorously seek play rewards, such as stars, medals, beads, win-or-lose titles, and so on. This is especially visible in materialistic societies. Hence, the amusing but rather sad quip: “The man who wins in life is the one who dies with the most toys.”

Human Cognitive Patterns

In “Sex and Cognition,” an impressive survey of male/female differences, behavioral psychologist Doreen Kimura concluded that “human cognitive patterns and their related brain organization are permanently influenced by physiological events [mostly hormonal differences] that take place by the fourth fetal month.” I should add that plenty of research shows that opposite-sex traits can be induced in males and females via hormones.

Boys and Girls Have Different Brains

Evolutionary psychologist Steven Pinker, in “The Blank Slate: The Modern Denial of Human Nature,” performed a definitive take-down of the centuries-old theory that the human brain begins life empty, so to speak—like a blackboard or slate with nothing written on it—and then is slowly made operational by physical stimuli and social conditioning. Not entirely so. Modern scanners have found that the physical brains of boys and girls are different in many fine details, especially from puberty onward.

Brain Metabolism

At the University of Pennsylvania School of Medicine, a combination of positron emission tomography (PET) scans and high-resolution magnetic resonance imaging (MRI) technology was used to study brain metabolism and showed that even while at rest, males and females differed in 17 areas of brain function.

Males and Violence

At puberty and through young adulthood (15–25 years of age), men are far more prone to physical violence and women more prone to emotional volatility. With age, men tend to become less aggressive (due to falling testosterone levels) and women more aggressive (due to falling estrogen levels). Researcher Glenn Wilson, in his very readable work “The Great Sex Divide: A Study of Male–Female Differences,” reported that about 85 percent of all crimes of aggression are committed by males, and there are specific, universal sex differences in the crime styles, types of victims, and post-crime behaviors of male and female perpetrators of violent crimes.

Spatial Skills

Research also shows boys are better than girls at a variety of spatial skills, such as mentally rotating a drawing of an object (called “imaginal rotation”), including 3-D rotation. This skill is cross-cultural and “practically universal” in males. This spatial skill sex difference becomes quite marked after puberty in humans, and is a sex difference also observed in animals.

Location of Objects

Women are superior to men at certain tasks requiring memory for the location of objects. This is especially evident during self-location in space: Women tend to do poorly at map-reading compared to men, opting instead to locate their position by memory of objects and landmarks (“turn left at the coffee shop”). Men, in contrast, tend to think in terms of compass directions (“turn north when you get to the corner”). Removing landmarks handicaps women, while changing dimensions handicaps men.  

The Aggression Difference

From birth, boys are more aggressive, competitive, and self-assertive than girls, and this is the most common finding, worldwide. Interest in this difference became mainstream in 1978 when professors Eleanor Maccoby and Carol Jacklin of Stanford University, both doctrinaire feminists hoping to find proof that there are no innate sex differences, “sifted the evidence” and simply surrendered. Their landmark publication, “The Psychology of Sex Differences,” offered a mass of evidence that the higher aggression of boys is innate and can’t be attributed to social construction.

I’m not sure why we needed social scientists to tell us this, as everyone knows that boys the world over are punished far more severely and frequently than girls for aggression, and nevertheless remain far more aggressive. And as one observer put it: Anyone who has raised both boys and girls and still thinks they are the same has already withstood far more evidence to the contrary than any social scientist could ever provide.

My addendum to this is that aggressiveness and control are very different. Just because men are generally more aggressive doesn’t mean they always end up with control. Everyone can think of couples where the male is more aggressive, but the female controls the relationship and the tenor of the family. I remember a great line from the movie “My Big Fat Greek Wedding.”

The mother says to her daughter: “The man is the head of the family. But the woman is the neck. And she can turn the head any way she wants.”  

An amusing and deep truth.

William Gairdner is an author who lives near Toronto. His latest book is “The Great Divide: Why Liberals and Conservatives Will Never, Ever Agree” (2015). His website is

William Gairdner
William Gairdner
William Gairdner is a best-selling author living near Toronto. His latest book is "Beyond the Rhetoric" (2021). His website is