ST Home Learning Centre By Andy Ho The Lesson Plan IT IS aimed at getting upper secondary and junior college students up to speed in current affairs and English, and comes in three parts: the story, the lesson and the worksheet. This week's story is about the prospects for improving human longevity. Read it once or twice for overall meaning. You may need to refer to the list of high-level words and important concepts that follow the article. Then do the exercises to improve your vocabulary and comprehension skills. The lesson plan is drawn up by PHILIP GEER, the author of numerous texts on English, including Simon's Saga for the SAT I Verbal and the forthcoming Picture These SAT Words! (both published by Barrons Educational Series). He is also the academic director of Mentaurs ( www.mentaurs.com ) , an education consultancy that designs materials and courses to improve students' English skills for the Scholastic Assessment Test and other tests. He can be reached at director@mentaurs.com">director@mentaurs.com The Story Live to 125? In your dreams WHATEVER the stem cell advocates say, you won't make it to 125 years old. Few of us will even beat 122, the record held by Jeanne Calment (Feb 21, 1875 to Aug 4, 1997), the oldest person who ever lived. Why, you're unlikely to even make it to 100, if Dr Jay Olshansky is proven right. IMPORTANT CONCEPTS stem cell: unspecialised human or animal cells that can produce mature specialised body cells and at the same time replicate themselves. Medical researchers are interested in using stem cells to repair or replace damaged body tissues because stem cells are less likely than other foreign cells to be rejected by the immune system when they are implanted in the body. genetic engineering: the use of various methods to manipulate the DNA (genetic material) of cells to change hereditary traits or produce biological products. A public health professor from the University of Illinois in Chicago, he is one of the main movers of a new discipline called biodemographics, the study of the social and biological factors that determine ageing, survival and longevity. In Singapore recently to speak at the Institute of Policy Studies, he offered a counterpoint to those who would have all of us live to 125. The affable academic, together with Harvard medical professor Thomas Perls, is being sued for US$150 million (S$252 million) by Dr Ronald Klatz and Dr Robert Goldman, co-founders of the American Academy of Anti-Ageing Medicine. The organisation is a Chicago-based body that organised an Economic Development Board-sponsored anti-ageing conference here last July. Three years ago, Dr Olshansky and other scientists began offering the Silver Fleece Award to expose what they called scammers who claim that their products can retard or reverse ageing. This year, Dr Klatz and Dr Goldman were conferred the award for their suite of anti-ageing products that are being sold on MarketAmerica.com Dr Olshansky said the advertising 'uses clever hype and pseudo-scientific mumbo-jumbo to convince consumers that 'nutraceuticals' and 'cosmeceuticals' can alter the ageing process. About the only thing these anti-ageing products do is to fatten the wallets of those selling them'. Why is an epidemiologist so cocksure? HIGH LEVEL VOCABULARY advocate n. those who argue for a cause discipline n. branch of knowledge or teaching counterpoint n. contrasting but parallel element or theme affable adj. easy and pleasent to speak to, approachable academic n. member of an instution of higher learning retard v. slow down epidemiologist n. one who studies the causes, distribution and control of disease in populations celebrated adj. known and praised widely stature n. natural height of a human in an upright position indefinitely adv. in a way that lacks precise limits prone adj. inclined eradicated v. got rid of reiterate v. repeat demographers n. people who study the characteristics of human populations and population segments egregiously adv. in a way that is conspicuously bad extrapolate v. estimate by projecting known information linearly adv. in a way that relates to or resembles a line First, Dr Olshansky reasoned, the human body is not biologically engineered to last into a second century of service. In a celebrated article in the Scientific American in 2001 headlined 'If humans were built to last', he and co-authors Bruce Carnes and Robert Butler presented a semi-serious caricature of how the human body would look if it were designed to last that long: re-wired eyes, bigger ears, curved neck, forward-tilting upper torso, shorter stature, shorter limbs and extra padding around the joints. The redesign served to highlight the biological limitations any effort to extend life indefinitely must confront - the eye's retina is prone to detach after years of use, fragile hair cells in our ears lead to hearing loss, our height makes for a higher centre of gravity, so falls and fractures in old age are common, and so on. Second, the big gains have already been made. The quantum leap in life expectancy in the 20th century came about because communicable diseases were eradicated, which added about 30 years to human life expectancy in developed nations. But this, Dr Olshansky argued, merely shifted death away from the very young to the old. For this reason alone, we can't expect to repeat the same increase in the future. That is, adding 70 years to a seven-month-old is do-able, but adding 30 years to a 70-year-old is probably quite un-doable. To reiterate, death rates declined dramatically at every age in developed nations in the 20th century, and life expectancy rose rapidly. Thus, life expectancy at birth for women in the United States rose from 48.9 years in 1900 to 79.0 in 1995. However, because infectious diseases are no longer the main cause of death at a young age, much larger reductions in deaths at older ages will be required to bump up life expectancy by any significant amount. What about stem cells, genetic engineering and all that? Can't they prolong life? Even if science could completely remove all causes of death at all ages under 50, the mathematical nature of the curve that demographers plot shows that it would add only about four years to life expectancy. Egregiously high figures - like living to 125 - come about only when non-demographers project or extrapolate directly or linearly from the data as if they made for a straight line graph. But that approach is ridiculous: 'Why not project life expectancy backwards in time linearly, in which case people should have lived zero years in 1750!' By the same token, if we could project biological phenomena YL parameter error 1linearly, given that the mile was run in five minutes in 1860 and these times have been falling, so it is 3 min 43 sec now, we should expect a mile in a minute by 2420, and zero time in 2580 - by teleporting perhaps. The graphs show that life expectancy will peak at 85 years in the current century. To go beyond 85, extremely large reductions in current levels of total mortality for both males and females are required. This is probably not do-able. What about seriously modifying biology, ageing genes in particular? Unfortunately - and this is Dr Olshansky's third point - 'there is no genetic programme for ageing. There is only a genetic programme for growth, development and reproduction'. Picture a garden dedicated to the immortality of DNA. In it, the DNA of all sexually reproducing species that ever existed is represented. Picture also, in the middle of it all, a statue that pays tribute to all that DNA. Ageing, decrepitude and senescence form but the shadow behind the statue. Nature focuses only on the statue, not the shadow behind it. In other words, ageing is incidental to the preservation of DNA. It is as if the body forms around the DNA as just a vessel to preserve and replicate DNA. Thus the longevity of a species is determined by how long one's fertile years are, a law that holds true across mammalian species, including mice, dogs and humans. Dr Olshansky observed that you must survive long enough to breed and nurture your offspring until they can do the same. Those of us who are healthy enough to reproduce will pass our genes on to our offspring. But beyond that, genes don't care. Genes that render individuals unfit for survival will get selected out as the afflicted will die before having any offspring. Obversely, genes that cause disability and disease after one has reproduced needn't be selected against, so they spread. In other words, since failing joints, eyes, hearts and brains after 50 don't get in the way of reproduction in our 20s and 30s, their causal genes, if any, get passed along despite the harm they inflict later in life. There is no penalty for such bad genes. In this sense, the setbacks of ageing are natural and inevitable. This imperative to preserve DNA, according to Dr Olshansky, explains nature's Gompertz's Law. In 1825, British actuarist Benjamin Gompertz observed that, across species, the risk of death is at its lowest during sexual maturity, only to rise exponentially between sexual maturity and old age. Here's the lowdown on why you have a body at all: You're here just to propagate DNA. How long you live after you're supposed to have done that, Mother Nature cares little. Since those genes that bring you senescence and trouble later on don't get in the way of that propagation, Mother Nature provides you no defence against them. Buddy, you're on your own. You're not making it to 125. The Worksheet WORDS IN CONTEXT Choose the definition that best expresses the meaning of the word or phrase as it is used in the passage. 1. make it (para 2) A. enjoy B. survive C. create 2. movers (para 3) A. important people involved in something B. protesters C. sceptics 3. suite (para 8) A. a retinue B. a set of matching furniture C. a group of related things intended to be used together 4. fatten A. increase the size of B. feed C. increase the amount of money 5. confront (para 13) A. come face to face with B. challenge C. refuse 6. bump up (para 18) A. damage B. increase C. exaggerate 7. seriously (para 25) A. very significantly B. maturely C. completely 8. vessel A. ship B. means by which something is done C. jar 9. observed (para 31) A. concluded based on evidence B. speculated C. watched 10. lowdown (para 37) A. purpose B. dirty trick C. real reason for COMPREHENSION THE following questions are based on the passage. Some also test your knowledge of rhetorical terms. 1. What mistake does the author say non-experts often make in interpreting data on human longevity? A. projecting future trends using a mathematically invalid procedure B. assuming that everyone will someday be able to live until 85 C. forgetting that Mother Nature doesn't care how long people live after they pass on their genes 2. The phrase 'Genes don't care' (para 31) is an example of A. understatement B. onomatopoeia C. personification 3. 'Here's the lowdown on why you have a body at all: You're here just to propagate DNA.' (para 37) Which term can most reasonably be used to describe this argument? A. inferential B. rhetorical C. reductionistic 4. Which of the following would be the best candidate for a Silver Fleece Award? A. a pill that increases a student's vocabulary by 1,000 words B. a study showing that better diet can significantly increase the lifespan of people in developing countries C. a study showing that 85 is the oldest age that most people can expect to live to 5. Which of the following is not a reason given by Dr Olshansky to support his view that the human lifespan cannot be extended much more? A. limitations in the design of the human body B. most of the increases in lifespan have already been made C. there is inadequate funding for genetic research 6. Where is the potential for increased life expectancy greatest? A. in developing countries B. in developed countries C. in countries with the most advanced genetic research programmes PROJECT WORK DISCUSSION How much scientific research should be directed at extending the human lifespan? ANSWERS Words In Context: 1. B 2. A 3. C 4. C 5. A 6. B 7. A 8. B 9. A 10. C Comprehension: 1. A 2. C 3. C 4. A 5. C 6. A