Unit 13. Sex and Gender

A woman is only a woman, but a good cigar is a smoke.

Rudyard Kipling

Exercise 1. What do you know about the sexes?

1. What are the physiological differences between individuals of male and female gender? What organs and organ systems differ between males and females?

2. What mechanisms and when determine the sex of the future individual?

3. What are the functions of reproductive hormones (sex hormones)?

4. What are the secondary sexual characteristics?

5. Why do women generally live longer than men?

6. Do men and women really have different patterns of mental activity and emotions? Are they genetically or socially programmed?

Exercise 2. Read the text to check some of your answers in Exercise 1.

Why is life expectancy² longer for women than it is for men?

Bertrand Desjardins, a researcher in the demography department of the University of Montreal, explains.

Men dying sooner than women makes sense biologically: because 105 males are born for every 100 females, it would assure that there are about the same number of men and women at reproductive ages. But even though women showed a longer life expectancy in almost every human society in the last decade of the 20th century, the size of the advantage varied greatly. For example, in the U.S. life expectancy was 73.4 years for males and 80.1 years for females, a difference of 6.7 years, whereas in France it was 7.8 years and in the U.K., 5.3 years. The discrepancy was much greater in some countries, with the difference in Russia reaching more than 12 years, but in others, such as India (0.6 year) or Bangladesh (0.1 year), it was much less.

The diversity in worldwide longevity alone indicates that the difference in mortality between the sexes is not purely biological and that there are intervening social factors. The current range of situations actually reflects different stages of a three-part historical evolution. Women most probably have a biological advantage that allows them to live longer, but in the past--and in several places, still today--the status and life conditions of women nullified this benefit. Today, given the general progress in female life conditions, women have not only regained their biological advantage, but have gone much beyond it, both because they tend to engage in fewer behaviors that are bad for health than men do and because they better profit from current advances in health care and living conditions.

The biological advantage that women have is taken as a certainty, because the mortality of males is higher than that of females from the very outset of life: during the first year of life, in the absence of any outside influence which could differentiate mortality between the sexes, male mortality is 25 to 30 percent greater than is female mortality. The genetic advantage of females is evident. When a mutation of one of the genes of the X chromosome occurs, females have a second X to compensate, whereas all genes of the unique X chromosome of males express themselves, even if they are deleterious. More generally, the genetic difference between the sexes is associated with a better resistance to biological aging. Furthermore, female hormones and the role of women in reproduction have been linked to greater longevity. Estrogen, for example, facilitates the elimination of bad cholesterol and thus may offer some protection against heart disease; testosterone, on the other hand, has been linked to violence and risk taking. Finally, the female body has to make reserves to accommodate the needs of pregnancy and breast feeding; this ability has been associated with a greater ability to cope with overeating and eliminating excess food.

Even though many biological and genetic factors have been identified, their overall effect is impossible to measure, especially given the influence of social factors on mortality. The extraordinary economic and social progress, that has occurred since the 18th century, has been accompanied by a dramatic reduction of the social differences between men and women and of the burden of motherhood, which had previously negated women's biological advantage. But the recent mortality trends have gone much farther than the mere recovery of an original advantage, creating instead a new advantage of greater magnitude for women. Observations indicate that the growing excess male mortality in industrial countries could be explained by the rise of so-called "man-made diseases," which are more typically male. These include exposure to the hazards of the workplace in an industrial context, alcoholism, smoking and road accidents, which have indeed increased considerably throughout the 20th century.

But if these diseases are the only explanation for longer female life expectancy, why has the gap continued to grow even though male and female behavior and life conditions have been converging in recent years? Part of the paradox can certainly be explained by the fact that this convergence is not absolute: male smokers tend to smoke more cigarettes than female smokers do, and men drive more recklessly than female drivers do, for instance.

French demographer Jacques Vallin has long been monitoring longevity in general and sex differences in mortality in particular. He adds to the above an interesting explanation of women's current mortality advantage that could explain the more recent trends: the dramatic increase in excess male mortality emerged as an equally dramatic progress in the general health conditions of our societies was taking place. He thus argues that beyond the negative behavioral or environmental factors that affect men more than they do women, there could be very well be a more fundamental difference in lifestyles that allows women to better benefit from the general progress in health. For example, although women now participate massively in the work force, their roles remain different and their professional activities are, on average, less prejudicial to their health. In addition, women often relate to their bodies, their health and their lives in general in a much different way than men do. To caricature, women seek beauty, men seek strength and power; thus, a woman's body must remain young and healthy as long as possible, whereas a man's body must be submitted to risks and challenges from an early age. The result is that women, much more than men, are attentive to their bodies and their needs and often carry on deeper dialogs more easily with their doctors. Hence, women, being more inclined to take care of their bodies and to prolong their lives, may be better able to glean greater profit from modern medical and social advances by practicing activities that are healthier and better protect their bodies. In this context, women's biological advantage now appears relatively minor in the total mortality differences between the sexes.

Exercise 3. Are the following statements true or false, according to the text?

1. Equal numbers of boys and girls are born every year.

2. Different economies demonstrate great diversity in average life expectancy.

3. There are no social factors accounting for the difference in male and female longevity.

4. Y-chromosome gives men biological advantage and better survival chances.

5. Historically men have enjoyed a better social position than women.

6. Men are exposed to a greater number of risk factors than women.

7. Women make better use of medical services and modern progress in science.

Exercise 4. Sex Differences in the Brain.

Men and women display patterns of behavioral and cognitive differences that reflect varying hormonal influences on brain development. Before reading the next text guess if the following statements generally refer more to men or to women:

1. Men/Women, on average, have stronger verbal skills (especially in writing).

2. Men/Women generally are better at mentally manipulating objects.

3. Men/Women have better memory for events, words, objects, faces and activities.

4. Men/Women are better at performing certain quantitative tasks that rely on visual representations.

5. Men/Women can better recognize emotions and show higher levels of empathy.

Exercise 5. Read the following article to check some of your answers in Exercise 4.

Girl Brain, Boy Brain?

The two are not the same, but new work shows just how wrong it is to assume that all gender differences are “hardwired”

By Lise Eliot   

 

As MRI scanning grows ever more sophisticated, neuroscientists keep refining their search for male-female brain differences that will answer the age-old question, “Why can’t a woman think like a man?” (and vice-versa). Social cognition is one realm in which the search for brain sex differences should be especially fruitful. Females of all ages outperform males on tests requiring the recognition of emotion or relationships among other people. Sex differences in empathy emerge in infancy and persist throughout development, though the gap between adult women and men is larger than between girls and boys. The early appearance of any sex difference suggests it is innately programmed—selected for through evolution and fixed into our behavioral development through either prenatal hormone exposure or early gene expression differences. On the other hand, sex differences that grow larger through childhood are likely shaped by social learning, a consequence of the very different lifestyle, culture and training that boys and girls experience in every human society.

At first glance, studies of the brain seem to offer a way out of this age-old nature/nurture dilemma. Any difference in the structure or activation of male and female brains is indisputably biological. However, the assumption that such differences are also innate or “hardwired” is invalid, given all we’ve learned about the plasticity, or malleability of the brain. Simply put, experiences change our brains.

Recent research by Peg Nopoulos, Jessica Wood and colleagues at the University of Iowa illustrates just how difficult it is to untangle nature and nurture, even at the level of brain structure. A first study, published in March 2008 found that one subdivision of the ventral prefrontal cortex - an area involved in social cognition and interpersonal judgment, known as the straight gyrus (SG), - is proportionally larger in women, compared to men. (Men’s brains are about 10 percent larger than women’s, overall, so any comparison of specific brain regions must be scaled in proportion to this difference.) Wood and colleagues found the SG to be about 10 percent larger in the thirty women they studied, compared to thirty men. What’s more, they found that the size of the SG correlated with a widely-used test of social cognition, so that individuals (both male and female) who scored higher in interpersonal awareness also tended to have larger SGs.

In their article, Wood and colleagues speculate about the evolutionary basis for this sex difference. Perhaps, since women are the primary child-rearers, their brains have become programmed to develop a larger SG, to prepare them to be sensitive nurturers. Prenatal sex hormones are known to alter behavior and certain brain structures in other mammals. Perhaps such hormones—or sex-specific genes—may enhance the development of females’ SG (or dampen the development of males’) leading to inborn differences in social cognition.

The best way to test this hypothesis is to look at children. If the sex difference in the SG is present early in life, this strengthens the idea that it is innately programmed. Wood and Nopoulos therefore conducted a second study with colleague Vesna Murko, in which they measured the same frontal lobe areas in children between 7 and 17 years of age. But here the results were most unexpected: they found that the SG is actually larger in boys! What’s more, the same test of interpersonal awareness showed that skill in this area correlated with smaller SG, not larger, as in adults. The authors acknowledge that their findings are “complex,” and argue that the reversal between childhood and adulthood reflects the later maturation of boys’ brains, compared to girls. (Adolescents’ brains undergo a substantial “pruning” or reduction in gray matter volume during adolescence, which happens about two years earlier in girls, compared to boys.)

However, in both studies, Wood and colleagues added another test that reminds us to be cautious when interpreting any finding about sex differences in the brain. Instead of simply dividing their subjects by biological sex, they also gave each subject a test of psychological “gender:” a questionnaire that assesses each person’s degree of masculinity vs. femininity—regardless of their biological sex—based on their interests, abilities and personality type. And in both adults and children, this measure of “gender” also correlated with SG size, albeit in just as complicated a way as the correlation between “sex” and SG size. (Larger SG correlated with more feminine personality in adults but less feminine personality in children.)

In other words, there does seem to be a relationship between SG size and social perception, but it is not a simple male-female difference. Rather, the SG appears to reflect a person’s “femininity” better than one’s biological sex: women who are relatively less feminine show a correspondingly smaller SG compared to women who are more feminine, and ditto for men.

This finding—that brain structure correlates as well or better with psychological “gender” than with simple biological “sex”—is crucial to keep in mind when considering any comparisons of male and female brains. Yes, men and women are psychologically different and yes, neuroscientists are uncovering many differences in brain anatomy and physiology which seem to explain our behavioral differences. But just because a difference is biological doesn’t mean it is “hard-wired.” Individuals’ gender traits—their preference for masculine or feminine clothes, careers, hobbies and interpersonal styles—are inevitably shaped more by rearing and experience than is their biological sex. Likewise, their brains, which are ultimately producing all this masculine or feminine behavior, must be molded—at least to some degree—by the sum of their experiences as a boy or girl.

And so, any time scientists report a difference between male and female brains, especially in adults, it begs the question, “Nature or nurture?” Is women’s larger SG the cause of their social sensitivity, or the consequence of living some 30 years in a group that practices greater empathetic responding? Wood and colleagues are among the few neuroscientists to analyze male-female brain differences for their relationship to gender type, as opposed to strict biological sex. Their findings do not prove that social learning is the cause of male-female differences in the brain, but they do challenge the idea that such brain differences are a simple product of the Y chromosome. (From Scientific American Online, September 8, 2009)

Exercise 6. Answer the questions using the information from the text:

1. Why is social cognition regarded a fruitful area of investigation?

2. What is nature/nurture dilemma?

3. What is straight gyrus (SG) and what is it responsible for?

4. How do researchers explain larger SG in women from the evolutionary perspective?

5. How did the results of the second study contradict those of the first?

6. What correlation between SG size and sex/gender was finally established?

7. How can it be interpreted?

Exercise 7. Divide into two groups. Each group should read either Text A or Text B about differences between the sexes. Then tell other students what you have read about.

Text A. Enzyme Lack Lowers Women's Alcohol Tolerance

By Harald Franzen

An international team of researchers may have found one of the reasons why alcohol harms women more than men: women, it appears, are deficient in an enzyme that helps metabolize alcohol. The findings appear in the April issue of Alcoholism: Clinical and Experimental Research. "It has been known for a long time that, in general, both women and female animals are more susceptible to the negative or toxic effects of alcohol," team member Steven Schenker of the University of Texas at San Antonio says. "This is true for the liver, heart muscle and skeletal muscle, and it may be true for the pancreas and the brain. In other words, there is something about the female gender that makes them more susceptible to toxic amounts of alcohol."

In the past scientists attributed this susceptibility to women's smaller body size and their relatively higher percentage of fatty tissue. For this study, however, the researchers focused on what is known as first-pass metabolism. Before alcohol reaches the blood stream, it goes through the stomach, where so-called gastric alcohol dehydrogenase (ADH) isozymes break some of it down. "In an earlier study we found that women have less of this ADH activity than men do," notes lead author Charles Lieber of the Mount Sinai School of Medicine. "Accordingly, women have a lesser first-pass metabolism and, therefore, for a given dose of alcohol, their blood level is higher than it is for men."

Following up on that research, the team recently turned their attention to the makeup of ADH. They found that one of the enzyme's three components, glutathione-dependent fomaldehyde dehydrogenase (x-ADH), is deficient in women, thus explaining their lower ADH activity levels. To Schenker, the take-home message is clear: "Women simply need to be more cautious than males in terms of the amount of drinking they do." (From Scientific American Online, April 16, 2001)

Text B. Data Trends Suggest Women Will Outrun Men in 2156

By Sarah Graham

Every four years, athletes from around the world travel to the Olympic Games to compete in the 100-meter dash, hoping to earn title of fastest man or woman on Earth. A new statistical analysis suggests that in the year 2156, the winner of the women's event may finally outrun her male counterpart.

Andrew J. Tatem of the University of Oxford and his colleagues collected the finishing times in the men's 100-meter dash run in 1900 and from 1928 (when the women's race was first run) to 2004. The winning times for both genders have been steadily decreasing, with female competitors improving at a slightly faster clip than the males. By plotting the results against the year of competition and extrapolating the results, the team determined that the fastest human on the planet could be a woman after the 2156 games. In today's issue of the journal Nature, they report with a 5 percent margin of error that the event could take place as soon as 2064 or as late as 2788, however.

Tatem is the first to admit that the study represents a purely academic exercise. A disease researcher by trade, he says the new study was a result of noticing a strong and interesting trend in sprinting. Indeed, the relationship was surprisingly linear and no other model fit the data as well. “We decided to throw caution to the wind and see if current trends continued, what would happen in the future,” he remarks. Potential confounding factors that are not addressed in the new analysis include illegal drug use, environmental conditions on race day, national boycotts and timing accuracy. In addition, some researchers contend that humans are hurtling toward the limits of their potential and that the winning times predicted for 2156 (8.079 seconds for the female champion and 8.098 seconds for the male winner) are simply beyond our grasp. The next chance to check the trend comes in 2008 at Beijing. (From Scientific American Online, September 30, 2004)

Exercise 8. Summarize all the information discussed in this unit and speak on the role of the sexes in nature.