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Ever wonder why Canadians live longer than Americans -- and why Japanese live longer than either? After all, Americans spend tons more money on health care, to say nothing of vitamin supplements and fitness clubs, yet the U.S. lags behind most other industrial nations in life expectancy. It's the kind of question I start asking myself every summer, as I start exercising more, eating less, and generally trying to get into better shape.
Like most people, I'm confused by what I hear and read on TV and in magazines about how to live a longer, healthier life. Given the spread of AIDS, the SARS outbreak, and all the other emerging threats to good health, I sometimes wonder if humans are going to survive at all.
For some sound, objective counsel on everything from what exercise to do this summer to the future of the human race, I turned to Jay Olshansky, a professor at the University of Illinois at Chicago and an expert on aging. He, and frequent collaborator Bruce A. Carnes, co-authored the well-received book, The Quest for Immortality: Science at the Frontiers of Aging, which came out in paperback last year. Here are edited excerpts of our talk:
Q: Why do women live longer than men?
A: There's no definitive explanation. The sex difference in longevity exists for most mammals, so it's obviously not [just] a difference in lifestyle, or smoking behavior, or [other] risky behaviors. There's clearly something biological that protects women longer than men from the major fatal diseases associated with growing older.
Q: You have remarked that we humans are already living past our product expiration date. What do you mean by that?
A: What we've essentially done during the 20th century is push many people to survive well beyond the end of our reproductive windows -- which is defined pretty much as when menopause occurs for women, even though some males are capable of reproducing later than that. It's just like driving your car beyond the warranty period. If you try to drive your car for 150,000 or 200,000 miles, some things are going to fall off that ordinarily you'd never see fall off.
Q: You're skeptical that average human life expectancy will top 100 anytime soon. Why is that?
A: Once life expectancy approaches 80, it's practically immovable. It can be [increased] -- it's close to 85 for females in Japan. But going from 70 to 85 is far easier than going from 85 to 100. It may very well be possible to get up to 85 -- that's 88 for women and 82 for men. But to go much beyond that is going to require modifying the basic biological rate of aging itself.
Q: You and Bruce Carnes did a bit of a tongue-in-cheek article saying that the ideal body type for longevity would be a short, squat elf. Why would that be?
A: We were trying to illustrate that the human body essentially was designed for short-term use. Very much like other living things, [humans] were designed to reproduce, make sure we pass our genes on, and then fade away. If we had been designed for a healthier life into old age, our body type would probably be different.
[So,] we [redesigned humans as] a shorter animal to lessen the risk of falls, tilted the upper torso forward 15 to 20 degrees to lessen the pressure on the lower back, reversed the knee joint to show that the current knee wasn't designed to be used for 9 or 10 decades, and made some changes in the eyes and ears because they change fundamentally in all of us as we grow older.
Q: O.K., so humans aren't perfect. But all other things being equal, why do some people live longer than others?
A: Let me start by saying that the main control we have over the duration of our lives is to shorten it. Smoking cigarettes, becoming obese, having bad dietary habits, exposing ourselves excessively to sun, alcohol, and toxins in the environment, all tend to accelerate both the aging process and diseases and disorders associated with aging. If you avoid those things, you're allowing your body to live out to whatever genetic potential it has.
You also have to add into the equation something over which we have no control -- the random damage that occurs to the basic building blocks of life on a daily basis. So, you [also] have to have won the genetic lottery. And you have to be lucky.
Q: Given that this is summer, and people are out tanning and doing other foolish things, what are the two or three things we can do that most assure a longer life?
A: There are two obvious things. One is [not to] expose ourselves to [sun]. Fortunately, there are all sorts of sunblocks that help reduce that exposure -- and protect the skin and the inside of our body against radiation. [On top of that], if you want to perform a lube, oil, and filter job on your body as you would your car, exercise! If anything can be considered the fountain of youth today, it's exercise.
Q: What do you personally do, and what do you recommend?
A: I do a combination of running and walking. Just walking is a wonderful, straightforward form of exercise. Swimming, bicycle riding, running. Then, of course, weight training is fantastic. I now have my 87-year-old father weight-lifting, and he has experienced tremendous benefits in a short period of time. Of course, you need to speak with a doctor [before starting].
Q: What about taking vitamins, antioxidants, growth hormone, and that sort of thing?
A: There's no evidence that any of those products make anyone live any longer. There may be some reduction of the risk of some diseases by ingesting certain antioxidants or vitamins like E, C, or calcium. These are all things that we know can ward off certain diseases. But you can't make up for a bad diet by eating vitamins and nutritional supplements. The only way you can make up for a bad diet is with a good one.
Q: Do you take vitamins?
A: No. I don't take any vitamins at all. I eat a normal diet.
Q: Is obesity a factor in lowering Americans' longevity?
A: We're writing a manuscript on that very issue now. The answer is: not yet. It's going to be an issue. Because we now have these huge cohorts of younger people who are obese. They're going to carry with them elevated risks for a number of diseases throughout their lives. [But] we're a couple of decades away from seeing the worst effects of obesity. That doesn't mean there isn't an effect today. I just think it's going to get significantly worse.
Q: Does that mean that the life expectancy of Americans will plateau or even fall?
A: Yes. I think it's likely that it will plateau and plausible that it will decline. That's precisely the topic of our paper.
Q: Big news! Is that mainly because of obesity?
A: Yes, and infectious diseases.
Q: Which infectious diseases?
A: Actually, I'm not going to talk about that [before the article is published]. I'll just say that in general we're setting ourselves up for a rise in infectious diseases. I mean the ones we already know about, such as the influenza virus that occurs every year, [and] new infectious diseases that are taking over subgroups of the population. For instance, West Nile virus, which is mosquito-borne, is something we never had in the U.S. until a few years ago. AIDS is another example.
Q: So do you think the life expectancy in industrialized nations and even worldwide might plateau for the same reasons?
A: Yes.
Q: Why do Asians -- people in places such as in Japan and Singapore --live longer than other people?
A: First of all, the Japanese tend to be much more homogeneous than we are in the U.S.
Q: I thought that would be bad in genetic terms.
A: No. In terms of mortality, some of the high risks present in the U.S. are among African Americans and Hispanics. And the percentage of African Americans and Hispanics in the total population has been increasing rapidly. They have a higher risk throughout the age structure.
Q: Is that because of genetics, diet, obesity, poverty, or what?
A: It's probably mostly environmental. There may be some genetic diseases that subgroups of the population are susceptible to, but I suspect that if everyone is given the same diet and exercise regimen, you probably would see pretty [similar] life expectancy throughout the world.
The Japanese are a bit different. They have practically no heart disease. They have higher stroke mortality because of their higher salt intake -- which is now on the decline.
Q: Is Singapore similar to Japan?
A: No. Singapore is three-quarters Chinese, with the rest [being] Indians and Malaysians. It's a very modern country with universal health care. In many ways it's an ideal environment.
Q: Canadians also live longer than Americans -- especially Canadian women, who can expect to live to about 83, vs. under 81 for American women.
A: I suspect that, again, it's an issue of homogeneity and heterogeneity. Canadians also have universal access to health care.
Q: What can we Americans do to increase longevity?
A: Well the first thing would be to reduce infectious diseases early in life among minorities. The biggest bang for the buck would be to go after malnutrition, provide better prenatal care, and reduce child/infant mortality among minorities.
But if you're asking: What's the one thing everyone in the population can do? It would be exercise. Exercise and diet are the two most important things we can do to influence the length and quality of our lives.
Q: What sort of diet should we eat?
A: Basically, a diet based on moderation that doesn't have too much fat, too much protein. [Also,] it would be a far wiser investment to take all the money you're spending on antioxidants and hormones and invest it in a good pair of walking or running shoes and membership in a fitness club. Just getting out there walking, moving, is absolutely the best thing you can do for yourself.
Q: What's your take on Botox injections and the other things people do to look younger?
A: I don't have any problem with people using creams, hair dyes and even plastic surgery. It won't make people live any longer, but it will make them look and feel younger. I don't see anything wrong with that.
Q: Is there an age past which you stop having a good quality of life -- where you become old, old?
A: No. You can have a high quality of life even past 100. [But simply] living longer is the wrong goal. Everything we do should be to enhance the quality of the days we have. We should not pursue life extension in and of itself. That, in my opinion, is a potential disaster. If all you're doing is extending life without improving the quality of life, the price we may pay is an increase in frailty and disability. We'd essentially be making ourselves older, longer. I can't think of anything worse.
Who Lives How Long Where
Life expectancies in selected countries around the world:
Country Men Women Average
Canada 76.3 83.3 79.7
France 75.2 83.1 79.1
Germany 74.6 81.1 77.8
Italy 76.1 82.6 79.3
Japan 77.7 84.3 80.9
Singapore 77.3 83.5 80.3
U.S. 75.3 80.8 77.4
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World 62.3 65.7 63.9
Data: The World Factbook 2002
Peterson is a contributing editor at BusinessWeek Online. Follow his weekly Moveable Feast column, only on BusinessWeek Online
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Copyright 2003, by The McGraw-Hill Companies Inc. All rights reserved.
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