Are there mental differences between women and men? A question that has been occupied by scholars for a long time, and has been covered by many studies, in the past and present.
In an article on The Conversation, biology professor Ari Berkowitz tried to track the results of studies conducted over a period of more than 100 years aimed at knowing the main differences between the brains of men and women.
These studies ultimately concluded that any gender differences in brain structures are likely to be due to a complex and interacting set of genes, hormones, and learning.
Allegations and Research
Berkowitz, director of the Graduate Program in Cellular and Behavioral Neuroscience at the University of Oklahoma, says that since at least the 19th century, scientists have been looking for differences in human brains of both genders.
The scientist Samuel George Morton claimed that he could determine the level of intelligence of a race by the size or size of the skull. And when Gustave Le Bon found that men's brains are usually larger than women's brains, this prompted Alexander Baynes and George Romanes to say that this difference in size makes men smarter.
However, John Stewart said that according to this criterion, elephants and whales should be smarter than humans.
Next, the focus is on the relative sizes of specific brain regions. The scientists suggested that the frontal lobe, the most intelligent part of the brain that is located above the eyes, is relatively larger in men, while the parietal lobe, just behind the frontal lobe, is relatively larger in women. Later, neuroanatomists argued that the parietal lobe is more important for intelligence.
Berkowitz says that in the 20th and 21st centuries, researchers tried to find distinct characteristics of females or males in smaller divisions of the brain, "but as a behavioral neurobiologist, I think this research is misleading because human brains are so diverse."
Anatomical brain differences
The largest and most consistent gender difference is found in the hypothalamus, which is a small structure that regulates the physiology and reproductive behavior. But the goal of many researchers was to determine the brain causes behind the assumed differences between the sexes in thinking, not just reproductive physiology, and so attention shifted to the large human brain, which is responsible for intelligence.
Within the brain, no region has received more attention in research on the differences between race and sex than the corpus callosum, a thick strip of nerve fibers that carries signals between the cerebral hemispheres.
In the 20th and 21st centuries, some researchers found that the entire corpus callosum is relatively larger in women, on average, while others found that only certain parts are larger. This difference drew attention to the fact that it may be what causes the cognitive differences between the sexes.
But smaller brains have a relatively larger corpus callosum regardless of the gender of its owner, and studies on differences in the size of this structure have been inconsistent. This is why trying to explain the assumed cognitive differences between the sexes - through brain anatomy - has not been so fruitful.
Prenatal hormones
A 1959 study showed for the first time that injecting testosterone into pregnant rodents made their female offspring exhibit male sexual behavior as adults.
The researchers concluded that the prenatal testosterone hormone, which is normally produced by the testicles of the fetus, permanently regulates the brain. Several subsequent studies showed this fundamentally to be true.
However, for ethical reasons, researchers cannot alter human prenatal hormone levels, so they rely on some "casual experience" when prenatal hormone levels or responses to them are abnormal.
But in these studies the hormonal and environmental influences were intertwined, and the results of the sex differences in the brain were inconsistent, leaving scientists without clear conclusions regarding humans.
Genetics and learning
While prenatal hormones may cause most of the sexual differences between non-humans, there are some instances when the cause is directly genetic.
This was most evident in the case of a zebra that had a strange anomaly (a male on its right side and a female on its left) and the brain structure associated with its singing was enlarged, as it is in a normal male, on the right side only, although the two sides faced the same hormonal environment.
Hence, his brain inconsistency was not caused by hormones, but by genes directly. Since then, direct genetics effects on gender differences have also been found in mice.
“A lot of people assume that gender differences in the brain are innate, but this is misleading,” Berkowitz says. Humans learn quickly in childhood and continue to learn more slowly as adults. And learning changes the connections between neurons. These changes are numerous and frequent but usually microscopic, less than 100 times the width of a human hair.
However, studies of extraordinary profession show that learning can change adult brains dramatically. So it is not realistic to assume that all gender differences in the brain are innate. It may also result from learning, as people live in essentially different cultures, and parenthood, education, expectations and opportunities differ based on gender, from birth to adulthood, which inevitably changes the brain.