Book 1 Reading and Speaking (1108795), страница 21
Текст из файла (страница 21)
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 differencesbetween the sexes. Then tell other students what you have read about.Text A. Enzyme Lack Lowers Women's Alcohol ToleranceBy Harald FranzenAn international team of researchers may have found one of the reasons why alcohol harms women morethan men: women, it appears, are deficient in an enzyme that helps metabolize alcohol.
The findings appear in the48April 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 memberSteven Schenker of the University of Texas at San Antonio says. "This is true for the liver, heart muscle andskeletal muscle, and it may be true for the pancreas and the brain. In other words, there is something about thefemale 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 higherpercentage of fatty tissue. For this study, however, the researchers focused on what is known as first-passmetabolism.
Before alcohol reaches the blood stream, it goes through the stomach, where so-called gastric alcoholdehydrogenase (ADH) isozymes break some of it down. "In an earlier study we found that women have less of thisADH 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 higherthan it is for men."Following up on that research, the team recently turned their attention to the makeup of ADH. They foundthat one of the enzyme's three components, glutathione-dependent fomaldehyde dehydrogenase (x-ADH), isdeficient 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 ScientificAmerican Online, April 16, 2001)Text B. Data Trends Suggest Women Will Outrun Men in 2156By Sarah GrahamEvery four years, athletes from around the world travel to the Olympic Games to compete in the 100-meterdash, hoping to earn title of fastest man or woman on Earth.
A new statistical analysis suggests that in the year2156, 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's100-meter dash run in 1900 and from 1928 (when the women's race was first run) to 2004. The winning times forboth genders have been steadily decreasing, with female competitors improving at a slightly faster clip than themales. By plotting the results against the year of competition and extrapolating the results, the team determinedthat the fastest human on the planet could be a woman after the 2156 games.
In today's issue of the journalNature, they report with a 5 percent margin of error that the event could take place as soon as 2064 or as late as2788, however.Tatem is the first to admit that the study represents a purely academic exercise. A disease researcher bytrade, he says the new study was a result of noticing a strong and interesting trend in sprinting. Indeed, therelationship was surprisingly linear and no other model fit the data as well.
“We decided to throw caution to the windand see if current trends continued, what would happen in the future,” he remarks. Potential confounding factorsthat are not addressed in the new analysis include illegal drug use, environmental conditions on race day, nationalboycotts and timing accuracy. In addition, some researchers contend that humans are hurtling toward the limits oftheir potential and that the winning times predicted for 2156 (8.079 seconds for the female champion and 8.098seconds for the male winner) are simply beyond our grasp.
The next chance to check the trend comes in 2008 atBeijing. (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 innature.49Unit 14. AgingWhat makes old age hard to bear is not the failingof one’s faculties, mental and physical but theburden of one’s memories.W. Somerset MaughamThe body is most fully developed from thirty tothirty-five years of age, the mind at about fortynine.AristotleExercise 1.
What do you know about aging?1. What is aging?2. What changes take place in human organism with age?3. How does aging affect the human brain?4. Is aging genetically programmed?5. Can aging be stopped or avoided?6. Do age-related diseases result from aging?Exercise 2. Read the article below and find answers to the questions:a. How does the text define and explain aging?b. What is the relation between aging and diseases?c. Do the authors agree that aging is genetically programmed? Why?No Truth to the Fountain of YouthWhat Aging Is... and Isn’tBy S. Jay Olshansky, Leonard Hayflick and Bruce A. CarnesAny discussion of aging should first clarify its terms. Various definitions have been proposed, but we think ofaging as the accumulation of random damage to the building blocks of life—especially to DNA, certain proteins,carbohydrates and lipids (fats)—that begins early in life and eventually exceeds the body’s self-repair capabilities.This damage gradually impairs the functioning of cells, tissues, organs and organ systems, thereby increasingvulnerability to disease and giving rise to the characteristic manifestations of aging, such as a loss of muscle andbone mass, a decline in reaction time, compromised hearing and vision, and reduced elasticity of the skin.This accretion of molecular damage comes from many sources, including, ironically, the life-sustainingprocesses involved in converting the food we eat into usable energy.
As the energy generators of cells(mitochondria) operate, they emit destructive, oxidizing molecules known as free radicals. Most of the damagecaused by these reactive molecules gets repaired, but not all. Biologists suspect that the oxidative assaultsultimately cause irreparable injury to the mitochondria, thereby impeding the cell’s ability to maintain the integrity ofthe countless molecules needed to keep the body operating properly. The free radicals may also disrupt otherparts of cells directly.Aging, in our view, makes us ever more susceptible to such ills as heart disease, Alzheimer’s disease,stroke and cancer, but these age-related conditions are superimposed on aging, not equivalent to it.
Therefore,even if science could eliminate today’s leading killers of older individuals, aging would continue to occur, ensuringthat different maladies would take their place. In addition, it would guarantee that one crucial body component oranother—say, the cardiovascular system—would eventually experience a catastrophic failure. It is an inescapablebiological reality that once the engine of life switches on, the body inevitably sows the seeds of its own destruction.Men and women in the developed world typically live longer now (75 and 80 years, respectively) than theydid throughout much of history (about 25 years) because human ingenuity—which brought us sanitation systems,vaccines, antibiotics and so on—has had phenomenal success in thwarting the infectious and parasitic diseasesresponsible for a great deal of premature death.
We live longer now not because we have altered the way we agebut because we have altered the way we live.Though inevitable, aging is not, as some might think, a genetically programmed process, playing itself out ona rigidly predetermined time schedule. The way evolution works makes it impossible for us to possess genes thatare specifically designed to cause physiological decline with age or to control how long we live. Just as anautomobile does not have a built-in plan for decline written in its blueprints, we do not possess genetic instructionsthat tell our bodies how to age or when to die.The logic behind this assertion goes basically like this: Genes perpetuate themselves by orchestrating thetransformation of a fertilized egg into a sexually mature adult that produces offspring.
Clearly, any genetic variantthat compromises this developmental process would be self-eliminating. Conversely, evolution is totally blind to theconsequences of gene action (whether good, bad or indifferent) after reproduction is achieved. Genes or geneticvariants that prove detrimental in the postreproductive part of the life span can become commonplace, but only if50they participate in important processes early on. For example, several genes that contribute to cancer in the lateryears are known to participate in growth and development early in life.Without a doubt, a host of our genes influence aging, but they do so indirectly, as an inadvertent by-productof processes involved in growth, development, and the maintenance of health and vigor. The lack of a specificgenetic program for aging and death means that there are no quick fixes that will permit us to treat aging as if itwere a disease.
A single genetic intervention in an organism as complex as a human being would have littlechance of combating the probably vast array of genes and biological activities that play subtle, unpredictable partsin the timing of our ultimate demise. (From Scientific American Online, December 29, 2008)Exercise 3. You are going to read an article about centenarians – people who are more than 100 years old.Before reading discuss the following questions:1.
Are there any biological limits to human life span?2. Have people reached the upper limit of longevity?3. How can average life expectancy be increased?4. Would you like to live to be a hundred years old? Why? Why not?Exercise 4. Read the text.Is 100 the New 80?: Centenarians Studied to Find the Secret of LongevityHealthy aging may be possible with some genetic helpBy Barbara JuncosaCentenarians—those who live past age 100—may help researchers find the key to living longer, healthierlives.
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