Women and Men have Different Brains … Right?
The reason that prompted me to write this article is that one of my relatives recently said something like this: “I think men and women truly have different brains. Women always think the issue came from their original family. I never think about those things because I know I don’t have any problem (with my original family).” After hearing this, my mind flashed back to a chapter of a book that I read for a course last semester called “Race, Gender, and Science.” Based on my personal judgment, I believe my relative, a CEO at a big AI company while also pursuing a Ph.D. degree, can surely understand scientific theories written from me, someone who is not a science major. So I thought to myself, he must not have the resources to read such a great article (yes, from me). Thus, I wanted to give him one more chance, to see if he was being ignorant or he was being ignorant (big smiley face here).
I will present the theories explained in the book Women and Gender, Transforming Psychology. The author Janice Yoder gave beautiful explanations of the history of how scientists think about gender-caused differences in brains.
Two scientists once asked undergraduate students what they think caused the biggest difference among men and women. Is it socialization, biology, or opportunities? More students thought that it is the socialization that caused the difference between men and women. The scientists also found out that the more students believe that the cause is biology, the more they think the cause cannot be eliminated. So, what do you think?
Before we get into the topic, please remember the term Biological Essentialism: it is the belief that what we do, think, and feel is rooted in our bodies (Bem, 1993). Thus, this belief thinks that the difference between men and women is inherent.
So the question is: are our bodies something that we can control, or are they just pure genetic?
Before answering this question, let’s look at what determines a male or female: chromosome, gonads, gonadal hormones, internal accessory organs, external genitalia, sex label, and gender of rearing (Money & Ehrhardt, 1972).
But you know what? It is totally okay if you don’t know what any of these means. Because what I’m about to talk about is more important. We usually think of sex as dimorphic, which means a person is either a man or a woman. However, reality will show us that we are naive.
For example, people with Turner’s syndrome have one unmatched X chromosome and thus fail to develop breasts. They have ovaries and uterus, which are underdeveloped, which means they will not have periods.
Genetic females are born with masculinized external genitals, so they are often mislabeled as boys. Thus, labeling all human beings into two categories may be a simple job for society, but this categorization leaves behind many people.
Obviously, biological factors contribute to who we are, but Yoder argues that Biological Essentialism goes too far by taking away our abilities to actively shape our bodies.
It is worth mentioning that since many scientists believe that experiments done on animals cannot completely present human behaviors, most of the experiments discussed here are done on humans.
I will present the argument in these areas:
- Theories of Brain Development
- Sociobiologists’ error on sex selection
Section One
Have you ever wondered how historical figures view differences between men and women? Let me open your eyes:
Aristotle: women are cold and moist in contrast to men, who are warm and dry. Because women do not generate sufficient heat to cook their blood, they do not purify their souls. Their power of reasoning is deficient.
Craniologists of the 18th and 19th centuries: there are many women whose brains are closer in size to those of gorillas than to the most developed male brains. This inferiority is so evident that no one can challenge it for a moment. All psychologists who have studied the intelligence of women recognize that they are the most inferior forms of human evolution and that they are closer to children and savages than to an adult, civilized man. They excel in fickleness, inconstancy, absence of thought and logic, and incapacity to reason.
Edward Clark, one of the leading educators of his day, argued that if women exercised their brains by pursuing education, their ovaries would shrivel.
Former Speaker of the US House of Representatives: if combat means being in a ditch, females have biological problems staying in a ditch for 30 days because they get infections, and they don’t have upper body strength. I mean, some do, but they are relatively rare.
We learned in school that a developing embryo contains 22 Paris of chromosomes and one pair of sex chromosomes. The sex chromosome is in charge of the development of the embryo’s reproductive structures. Thus, a girl baby usually gets two XX, and a boy baby usually gets an X from mommy and a Y from daddy. This Y chromosome is dedicated to male embryonic development.
So what does this have to do with brain development?
In the first six weeks of the fetus, XX and XY are not anatomically different. During the sixth week, the little Y is activated and can start to produce a protein called H-Y antigen. This protein will promote XY chromosomes to organize into an embryonic testis. From there, we have anatomically different XX and XY. The testis contains sperm-producing tubules and can synthesize two hormones: one to block further female development and the other to promote male development.
So we have talked about what the Y chromosome does to male babies. What about XX chromosomes in female babies？
Well, we actually don’t know enough about it. One is because of technological restraint. The other reason is that more scientists believed that female embryo development was passive, which means it resulted from not having a Y chromosome to work. If everyone is in an environment and culture that believe “female bodies are the result of not having the Y chromosome,” scientists, as they are also humans, are more prone to take that as a hypothesis but not experiment goals.
In 1992, research showed that the X chromosome’s impact in female embryo development might be similar to the impact of the Y chromosome in male embryo development, but more research is needed.
So I did a little research on that. Recent studies show that males who lack estrogen could lead to cortical bone development, glucose, and lipid metabolism abnormalities. It could also lead to reproduction problems (infertility) (Stephen & Ellis 2019).
For females, actually, serum androgen levels in women are higher than estrogen levels most of the time. It is only during the preovulatory and mid-luteal phases of the menstrual cycle when androgen and estrogen levels are similar.
But it remains unknown about androgen’s impact on female bone development. Since male bone development is usually bigger than female’s, we would think that maybe the level of androgen can impact bone size. However, we still need more researches.
We know that females and males all have estrogen and androgen, and females tend to have more estrogen; males tend to have more androgen. However, the difference is not that obvious many times. During the 14–20 weeks of pregnancy, 25% of the male babies have overlapped androgen levels with 9% female babies (Finegan, Bartleman, Wong, 1989).
The only time that there isn’t really any overlapping of androgen levels is during puberty. It depends on women’s menstrual cycle. Thus, we can only say that generally speaking, women have more estrogen, and men have more androgen.
Section Two: Theories of Brain Development
Now, there are at least three “famous” theories of brain development:
- Brain structures, once organized, are permanent and unchangeable
- There are two types of brains: female and male
- These two types do not overlap so that they clearly distinguish women form men
In the 1990s, there was raging attention on how to measure brain size and the connection between brain size and intelligence. Some reported that because men have more mature and bigger brains, they have higher IQs than women. Others said that this is why boys can do math better than girls. There were even connections about why men lose keys often, but women can find them…
The truth is, the brain remains a mystery to scientists.
After researching with a sample of only five female and nine male brains, two scientists claim that
- the shape of the brain differs between sex, such that females have bulbous brains, whereas males have cylindrical brains. I used my great imagination and drew something like this?
- The width of the splenium is so distinctively different that even an idiot can identify the sex of any brain.
- there is a sizable sex difference in splenial surface area (with p = 0.08, not reaching statistical significance). They claim that their research has “widespread implication to human evolution.”
Afterward, a scientist tried to cite follow-up studies to confirm this study, but only to find out these studies had seriously conflicting results.
So, is it reliable to say that there is a left brain and a right brain？
What scientists have found out is that the two hemispheres of the brain process information differently, with the left side being verbal (controlling language, speech, reading, and writing) and the right side being visual, spatial, and musical. However, pop psychology has “taught” us how to balance our left and right brains to enhance sexual pleasure…
So what do left and right brains have to do with women’s and men’s brains?
Researchers believed that men’s brains show greater specialization, while women’s brains engage in both forms of cognitive processing. Obviously, the assumption of this research is the more specialization, the better.
This theory has also been used to explain why boys can do math better than girls again. I had also thought that boys can do math better than girls when I was young because that was what everybody around me said. However, I now believe that it results from social/cultural cognition rather than sex differences.
In a book I read, Whistling Vivaldi, a Harvard president, once spoke at a women scientist conference in 2005 and said that “he believes the ability to do math differs solely on sex differences.” This became very controversial. Eventually, he resigned.
Having an interest in this topic, the author of the book conducted an experiment with their colleagues. They found a group of all male college students and another group of all female college students to complete a math test. Even though they tried to find students with the same math abilities, the result was still the classic “male students received higher scores.” So they thought to themselves if what gave female students the most pressure is from the unseen discrimination /stereotype, would eliminating that stereotype raise the test scores?
So this time, instead of simply giving the test, they said to female students: “You might have heard that boys do math better than girls. But actually, we have found out that girls do just as well as boys in this particular math test.” What do you think is the result? The result is that female students completed the test with identical scores as male students.
Do different brain functions reflect differing brain structures? We still don’t know yet. But how much of this is caused by our external environment (society) also remains unknown.
We know that the menstrual cycles of roommates and close friends synchronized across the first four months of dorm life. Thus, we know that close social interaction could suggest that environment can change biology. Even though there are differences between brain structures or functions, w would not know if brain differences cause sex differences or do sex differences produce different brains?
Section Three: Sociobiology
Have you ever heard about theories saying that women need to be especially careful to find a good husband?
Have you ever thought (except that this does not make any sense at all) about why people would say that?
Because people say similar things in different countries as well. One reason could be “interest conflict” explained by sociobiologists:
For males, sperm is cheap. You just need a little time, just need one sperm to work, and then you can have a baby.
But for females, once pregnant, the next 9 months, you have put yourself into a miserable time. At the same time, men could go on and find someone else to have another baby…
Thus, females need to find a partner who does not do what I just portrayed. But males are more concerned with whether they are the father.
They have also expanded the connection on why men dominate the workforce while women take care of the home.
Moreover, we have other theories explaining the mystery behind the height and strength difference between males and females.
So what is the truth? The truth is that the US Army found out that with the appropriate amount of training, women can load trucks, fix heavy equipment, and march with loaded packs as well as most men.
Additionally, we have job requirements that come with weird and unnecessary tests. For example, examining grip strength for police officers both disadvantaged women and had dubious job relevance (Arvey, Landon, Nutting, Maxwell, 1992).
Impressively, within 20 years, female marathon runners have narrowed the gender gap from 80 minutes to just 15 minutes! Thus, even if genes play a role in setting size and strength potentials, we know that training, exercise, diet, attitudes, and so on can make a big difference in what each individual achieves.
Regarding the theories that say “men are hunters and women are gatherers,” feminists responded:
1) This presumption is naive because we observe a wide range of behaviors across cultures and species.
2) There are no specific linkages between particular genes and human behaviors.
3) Some critics argue that sociobiologists use circular reasoning, which means reasoner begins with what they are trying to end with. For example, Time magazine speculated that women today are expected to be better than men at recalling objects scattered on the table because it was adaptive for women as gatherers to remember where foods were located. Finding that women list more items than men, they used this evidence to argue that women are genetically shaped by their past roles as gatherers (to make it simpler, I drew another beautiful diagram).
Scientists argue that cultural invention can overshadow these presumed genetic limitations.
For example, planes give us the ability to fly, antibiotics challenge our susceptibility to infection, and refrigeration freed us from mere survivalists. Sociobiologists ignore the roles culture, history, and technology play in influencing our lives by focusing on evolutionary adaptation alone.
Conclusion
Let’s imagine this: in a society, we tell half of the population to wear pink dresses while not showing their panties. We tell the other half to wear pants and encourage them to do outdoor activities.
We asked half of the population to keep slim during puberty and the other half to eat like a grown man. When they become adults, half of them wear high heels, and the other half wear sneakers. It is not hard to imagine that the two groups will have different biological and social features.
When what we are studying are two groups that never have equal access to resources and power and live in different environments, we cannot sort nature from nurture.
Stereotypes and discrimination against females have never ended. Of course, the way I look at this is you have the freedom to not learn more about this. You have the freedom to have stereotypes. But, what you should remember is, your stereotype does not have to do anything with other’s behaviors. It is you who choose to be immature, not anybody else.
Of course, while reading this article, we have seen science not being objective. After all, anything that is done by humans is hard to be objective. But, this is also why we should do more experiments on the right path to learn more about things that we don’t already know.
When I first read the book, I was still pretty shocked, even though I never really had any thoughts about what boys should do and what girls should do. But, I thought that many of the differences between men and women are born. After reading this book, I feel that there could be potentially nothing different between men and women.
I have seen both men and women who have personalities, or personal interests which traditionally speaking does not belong to their sex. But to me, this is just who they are. Meeting this person also reminds me of the reality of being a human — we share the same genes, potentially different skin color, potentially different interests, but we are all trying to live a fulfilled life!
So, after reading this article, if you are gonna answer this question again,
Will your answer change?
Reference：
1. Yoder, Jan. Women and Gender: Transforming Psychology (2nd Edition). Subsequent, Prentice Hall, 2002.
2. Hammes, Stephen R., and Ellis R. Levin. “Impact of Estrogens in Males and Androgens in Females.” Journal of Clinical Investigation, vol. 129, no. 5, 2019, pp. 1818–26. Crossref, doi:10.1172/jci125755.
3. Steele, Claude. Whistling Vivaldi: How Stereotypes Affect Us and What We Can Do (Issues of Our Time). Reprint, W. W. Norton & Company, 2011.
