Bruce J. Klein, director at the non-profit Immortality Institute, discusses the lengthening of human lifespan past, present and future. Huge gains have been made, and there is more to come from the medicine of tomorrow. Copyright © Bruce J. Klein

Figure 1. Source: sciencemag. This figure illustrates the enormous gains in life expectancy over the past 160 years.

Can all of this wonderful life extension continue? Will average lifespan continue to outpace projections? More importantly, can we find a cure for aging altogether or will the bubble burst like some overbought technology sector? Perhaps lifespan will peak at some natural limit. While the answer remains unclear, humans are healthier and are living longer than ever before.

Average Human Lifespan

"Out, out, brief candle! Life's but a walking shadow"

- William Shakespeare

With few exceptions, 30,000 days is the average human lifespan - 40,000 if you're lucky. However, two-thousand years ago average life expectancy was less than 20 years or about 7,000 days. It is difficult to imagine, but most of our ancestors kicked the bucket before our modern legal drinking age.

Bacteria, predators, accidents, extremes in weather and the lack of a reliable food source meant humans led short, dirty, brutal existences. That is if they survived birth at all. Infant mortality rates ranged from 300 or 400 deaths per 1,000 live births in the 18th century, while we see only seven per 1,000 today.

In 1796, life expectancy hovered around 24 years. A hundred years later it doubled to 48. In our modern world of air conditioners, hand washing and booster shots, you have a good chance of living 63 years, which is the world average. However, for those fortunate enough to live in a first-world country, lifespan jumps considerably.

Japan for instance has the longest average life-expectancy of 80 years, according to government figures. Similarly, in the United States, a baby born today can expect to live to 77. Interestingly these numbers continue to rise not only in developed countries but all over the world as well. When statistics are placed to a graph, the numbers speak for themselves. (Figure 1. above)

Separating the figures by gender, men on average live to 72, while women live to 79 in the US, a difference of seven years according to the 2001 CIA World Factbook. This difference is not fully understood, but it has something to do with genetics and hormonal differences between the sexes. Scientists are looking into to such difference for clues about the aging process.

Maximum Human Lifespan

"Over half the baby boomers here in America are going to see their hundredth birthday and beyond in excellent health," says Dr. Ronald Klatz, founder and President of the American Academy of Anti-Aging Medicine. "We're looking at life spans for the baby boomers and the generation after the baby boomers of 120 to 150 years of age." (4)

According to a longevity study conducted by John Wilmoth (5), a UC Berkeley associate, the "oldest age at death for humans has been rising for more than a century and shows no signs of leveling off." Wilmoth and fellow colleges from the United States and Sweden researched the national death records in Sweden and found an increase in the average maximum lifespan each year since 1861. This finding calls into question the 120 lifespan limit.

"We have shown that the maximum life span is changing. It is not a biological constant. Whether or not this can go on indefinitely is difficult to say. There is no hint yet that the upward trend is slowing down," writes Wilmoth.

Wilmoth's statements about maximum lifespan run counter to a commonly held belief that there is a natural limit. "Those numbers are out of thin air," said Wilmoth. "There is no scientific basis on which to estimate a fixed upper limit. Whether 115 or 120 years, it is a legend created by scientists who are quoting each other." says Wilmoth.

Will the Trend Continue?

"Aging is a biochemical process and humans will learn how to intervene in it and slow it down" Nick Bostrom, founder of the World Transhumanist Association predicts in his article Case Against Aging(1). Optimistically, Bostrom see the elimination of aging as "theoretically possible." While it may not be within reach now, it will be soon.

Current trends seem to prove Bostrom correct. Evidence for an ever increasing human lifespan -- as a result of advances in medicine and improvements in quality of life -- is quite impressive. Not only is there mounting statistical evidence for a continued upward trend, there's evidence this trend is actually accelerating.

Väinö Kannisto, a Max Planck Institute demographic researcher has compiled statistics from 28 countries. He found that as life expectancy rose during the 20th century the "pace of mortality improvement at older ages accelerated." Kannisto notes that even after age 100 "death rates are falling." (2)

"The conventional view is that future gains in life expectancy cannot possibly match those of the past," says Jay Olshansky (3). Olshansky believes the "sustained improvement" we're seeing in lifespan goes beyond this onetime statistical abnormality. "Reinforcing processes may help sustain the increase in record life expectancy" Olshansky says. Greater attention to health and more resources spent to combat diseases at all stages in life will result in a net increase in the number of people surviving into older age.

122 years - Current Lifespan Record

The only verified case of a human to live beyond 120 years was Jeanne Calment. She was a Frenchwoman who died in 1997 at 122 years. She rode a bicycle to the age of 100 and once met Vincent Van Gogh in her father's painting shop. Her longevity is likely linked to her genes as well as her lifestyle and the advance of medical technology during her lifetime. Her father lived to the age of 94 and her mother to the age of 86.

Oldest Living Person Today

Keeping track of who's the oldest, you need to look to Japan. According to Guinness World Records, Japan is home to the world's oldest woman, Kamoto Hongo, who turned 115 in 2002; the oldest man, 113-year-old Yukichi Chuganji; and the community with the highest proportion of centenarians - 33 people per 100,000 in Okinawa.

"One of the assumptions is that life expectancy will rise a bit and then reach a ceiling it cannot go through" says Mr Oeppen (4), senior research associate at the Cambridge Group for the History of Population and Social Structure. "But people have been assuming that since the 1920s and it hasn't proved to be the case." However, Oeppen is quick to point out, "This is far from eternity: modest annual increments in life expectancy will never lead to immortality."

Carefull what you say about immortality, it could put you in the hot seat of the nation's top bioethics advisor, Leon Kass. Bush's leading scientific advisor has gone out of his way to lambaste the possibility of immortality. Kass recently traveled to Toronto where he gave a conference entitled "Why not Immortality"(5). While his arguments against immortality are framed in eloquent phrases of modern bioethics, the core message is clear - Kass thinks that extending healthy human life is a bad idea. "Confronted with the growing moral challenges posed by biomedical technology, let us resist the siren song of the conquest of aging and death." Kass says.

On the other hand, there is a growing professional contingency willing to speak up on the topic of immortality. William Faloon,(6) president of the Life Extension Foundation, says, "History has often shown that before a major breakthrough occurs, experts go out of their way to deny that it will ever happen." Lifespan projections do not take into account "dramatic advances in the biomedical sciences." Fallon says. If these breakthroughs do come about "life expectancy will be significantly higher".

Jay Olshansky, author of The Quest for Immortality, expresses his optimism, "We see ourselves on the cusp of the second longevity revolution." However, Olshansky is not prepared to declare that immortality is in sight. "Short of medical interventions that manufacture survival time," Olshansky says, "there is very little you can do as an individual to extend the latent potential for longevity that was present at your conception." (Of course, there is a great deal that each individual can to to make sure they reach that full potential: lifestyle, diet and good medical care are all essential for a long, healthy natural lifespan).

Betting on Life Extension

"Our body design, although beautiful to behold, miraculous in design and astonishing in its complexity, was never intended to be operated in the laboratory of extended life," Olshansky said. Confident about his perdition, Olshansky has bet(8) $500 million that no 150-year-old person will be alive and in good condition by the year 2150. Taking the other side in this bet is Steven Austad, author of "Why We Age: What Science Is Discovering About the Body's Journey Through Life,". Austed recently made a presention on anti-aging and life extension medicine to the President's Council on Bioethics. Each scientist has endowed $150 to a trust fund that with the magic of compounding interest will produce a $500 million payout on January 1, 2150.

Centenarians on the Rise

As reported on the font cover of USA Today (August 24, 1999), The U.S. Census Bureau forecasts that the number of Americans age 100 or older will increase by more than 22 times the 1990 estimate of 37,306. In October 2001, the US Census Bureau actually reported that there were 50,454 US Centenarians (a more reasonable 35 percent increase) out of a total population of 281.4 million Americans. But by 2050, "the number of US centenarians is expected to reach 834,000 and maybe even 1 million," said Dr. Robert Butler, President of the International Longevity Center in New York City.

The number of people older than 100 in America has been increasing by more than 7 percent per year since the '50s. The fastest-growing group of drivers in Florida is over 85. Most researchers believe centenarians are only modern phenomenon. Jean-Marie Robine, with the National Institute of Health and Medical Research in France, believes that there were no true centenarians before 1800. Every pre-1800 case of supposed centenarianism they have investigated has turned out to be either provably false or impossible to confirm, Robine said.

Robine observed that the rising population of centenarians in France -- from an estimated 200 in 1950 to a peak of 10,000 today -- are proving that old notions of longevity are wrong.

"If we believe that there were no centenarians before 1800, the lifespans that we are seeing today, such as Mme. Jeanne Calment who lived to age 122, are even more surprising," Robine said. "If you go back into literature about human longevity, you find that the maximum is 110 and 112, and the authors keep increasing the number. After Jeanne Calment lived to 122, for two or three years no one proposed a new figure. Now you can see that there are new propositions of 125 and 130 as the maximum, but there is still no scientific basis to these propositions." (9)

In developed countries the number of people celebrating their 100th birthday multiplied several fold from 1875 to 1950 and doubled each decade since 1950. In Denmark, for instance, an average of only 3 individuals reached age 100 in each year of the 1870s, compared with 213 new centenarians in 1990. (A)

It has been speculated that centenarians may have been rare or even non-existent a few hundred years ago. According to J.R. Wilmonth, "true centenarians may have been quite rare in the pre-industrial period." Similarly, Jeune suggest that no humans lived to age 100 before 1800.

Life Extension Technology

In 2000, the budget for the National Institutes of Health was $15 billion. The research and development budgets of the major pharmaceutical companies was in excess of $20 billion. The majority of these funds is focused on the big killers: heart disease, cancer, and diabetes. As more attention is paid to an aging population, we can hope to see more of these funds funnelled into research specific to anti-aging. A cure for aging will likely come about from one or more of the following technologies:

1. Genetic Manipulation

With the human genetic code now mapped, the race is on to find anti-aging genes.

2. Stem Cells

While still a hot button issue, the potential of theraputic cloning and regenerative medicine using stem cells is enormous. Imagine growing a new heart from your own stem cells, creating a replacement organ without the dreaded problem of immune rejection from your body.

3. Small Biomechanical Devices

With smaller technology showing more and more promise, doctors are willing to take a look at Microelectromechanical System, MEMS and Nanotechnology for less invasive devices to monitor and repair aging cells and organs.

There is still a lot of work to be done yet. Many difficult problems must be solved on multiple fronts before we see lifespans of 150 years and beyond. Nevertheless, radical life extension and the potential for immortality could soon be at hand.

References:

1. Ron Katz - http://www.viewzone.com/aging.html

2. December 2, 2002 "Why Not Immortality," Ninth Annual Alloway lecture of the University of Toronto's Joint Centre for Bioethics

3. Nick Bostrom - http://www.nickbostrom.com/aging/aging.html

4. See reference (13) of the main text and V. Kannisto, Development of Oldest-Old Mortality, 1950-1990 (Odense Univ. Press, Denmark, 1994) online at http://www.demogr.mpg.de/Papers/Books/Monograph1/OldestOld.htm

5. [S. J. Olshansky, B. A. Carnes, and A. Désesquelles, Science 292, 1654 (2001)]

http://www.sciencemag.org/cgi/content/full/296/5570/1029/DC1

6. Jim Oeppen - http://news.bbc.co.uk/1/hi/health/1977733.stm

7. Leon R. Kass - L'Chaim And Its Limits: Why Not Immortality? http://www.petersnet.net/browse/4149.htm

8. William Faloon - http://www.lef.org/magazine/mag2002/sep2002_awsi_01.html

9. http://www.asaging.org/at/at-206/Living_to_100.htm

10. "The Emergence and Proliferation of Centenarians" by James W. Vaupel & Bernard Jeune Mar. 2000

11. John Wilmouth - http://news.bbc.co.uk/1/hi/health/946452.stm