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.

Unit 14. Aging

What makes old age hard to bear is not the failing of one’s faculties, mental and physical but the burden of one’s memories.

W. Somerset Maugham

The body is most fully developed from thirty to thirty-five years of age, the mind at about forty-nine.

Aristotle