Sunday, June 26, 2011

Life expectancy and lifespan: How to increase longevity?

Today there are more and more people living to be centenarians in the United States. In 1986 there was one centenarian per 10,000 elderly (defined as over 65 years of age) and by the year 2080 that number is expected to be 250 per 10,000. The 1990 census reported 35,800 Americans over 100 years old and 28,000 of them were women. In addition, it was predicted by the Census Bureau that the number of Americans over 100 years old will more than double to 80,000 by the year 2000. In fact, the most rapidly growing segment of the population is the 85 and older group. Between 1960 and 1980, that group increased by over 141%.

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Mariam Amash, 120, Israel

Although there are more centenarians today than ever before, and thus our life expectancy is gaining tremendous grounds, our potential lifespan has not changed. Life expectancy is the age at which an individual born into a particular cohort is expected to die, as a child born in 1900 had an average life expectancy of 48 years. If born today, your life expectancy would be 75 years for a man and 80 years for a woman. In this past century alone, the average life expectancy in the United States has increased by almost 40 years which is a greater gain than made during all of human history. The most important contributing factors to this increase in life expectancy were improvements in public health and the discovery and use of antibiotics.

But how long can human beings live? Lifespan or "the maximum age that could be attained if an individual were able to avoid or be successfully treated for all illnesses and accidents" is generally agreed to be 110-120 years. Interestingly, our potential lifespan has not changed in over one hundred thousand years, so the amazing increase in life expectancy does not reflect any reduction of the basic aging process itself.

One hundred and twenty years is considered the ideal human life-span, as stated in Genesis (6:3): “G-d said: ‘My spirit shall not abide in a human forever, since a person is also flesh; therefore a person’s days will be 120 years.’”

Adam, the first man, lived 930 years. And Methusalah, seven generations later, is renowned for his extraordinary longevity: 969 years. But by the era of the patriarchs, the normal human life-span had apparently dropped closer to a biblical life-span of 120 years. (Abraham lived 175 years, Sarah lived 127 years, Joseph lived 110 years, etc).

Only one person in the Torah lived exactly 120 years--to the day. According to the Midrash, Moses was born and died on the 7th day of Adar (which is today). Many understand the significance of his death at precisely 120 years to be a statement attesting to the fact that he had, without question, completed his life’s work.

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Hendrikje van Andel-Schipper, 114, Holland

But, in our times, there are quite few people who can reach 120 life mark. Walford writes that two persons have lived to 113 and one to 119 years. However, Georgakas states that Delina Filkins, 113, of New York is thus far the best documented centenarian (May 4, 1815-December 4, 1928). Currently, there is a woman living in England who is counting the minutes since she turned a documented 120 years. Many have claimed lifespans greater than 113 years and some up to 170 years, but Georgakas research has not borne these claims out.

The best-documented oldest living human being was Frenchwoman Jeanne Louise Calment, born on February 21, 1875. She lived to be 122 years old, dying in 1998. Ms. Calment came from good genetic stock–her father lived to 94, and her mother to 86. Defying conventional wisdom, she smoked until 1995, only giving up the habit out of pride at not being able to light her own cigarettes. Her sense of humor always remained, however (when asked about her vision of the future, she replied “very brief”).

Why, if life expectancy has increased so impressively, has not the human lifespan? Leonard Hayflick, professor of anatomy at the University of California, San Francisco, School of Medicine and a "dinosaur" specialist on aging, states that nature did not design us for great longevity. The goal is survival of the species which translates to getting offspring to sexual maturation and independence. Therefore, by age 30 we are coasting on our reserves. Hayflick states that our life expectancy would increase to about 91 (from 75) if cancer, heart disease and strokes were cured, but it would add no more than 3 years to our lifespan. Why? Because at around 100 years of age, all of our organs functional abilities have dramatically declined, so our only hope of an intervention is to first discover the cause of aging. Currently, our chances for living to our maximal lifespan, approximately 115 years, are 1 in 4 billion!

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Besse Berry Cooper, 114, USA

Predictors of longevity

What will increase your odds of being the 1 in 4 billion who lives to actualize your lifespan potential? The Roman historian and philosopher, Lucius Auraeus Seneca (4 B.C.-A.D. 65), thought he knew: "It is not the rich and the great, not those who depend on medicine, who become old; but such as use much exercise, are exposed to fresh air, and whose food is plain and moderate, as farmers, gardeners, fishermen, laborers, soldiers; and such men as perhaps never employed their thoughts on the means which have been used to promote longevity. It is among these people, chiefly, that the most astonishing instances of it are observed. Sometimes in these situations, man still attains to the amazing age of 150 years, and upward".

Although Senecas belief of a 150 year old in Roman times was a definite exaggeration (life expectancy was 22 years!), his "formula" for the longest living persons was probably fairly accurate.

Several others have formulated profiles that constitute predictors of the longevous. Dr. G. M. Humphry, professor of surgery at Cambridge, examined 900 patients who were at least 90 years old and approximately 52 were centenarians. The 100 year olds consisted of 36 women and 16 men. The following data was compiled:
-The majority were light to moderate eaters and consumed very little meat.
-Most awakened early and enjoyed outdoor work.
-40 of the 52 drank alcohol.
-Few reported having had many illnesses.
-44 said they were excellent sleepers, most of them averaging over 8 hours a night.
-A large number stated they were from long lived families, but long lived was not well defined.
-12 were first born children
-Over 2/3 of the women had been married and raised large families.
-10 out of the 11 who were over 102 years old were female, the oldest being 105 years.

One of the most famous studies designed to isolate the best predictors of life expectancy was the Duke Longitudinal Study of Aging. Based on this study of 270 volunteer men and women between the ages of 60-94, Palmore, developed a mathematical model that helped predict direct and indirect variables that influence life expectancy. The strongest predictors of longevity were:
-Only the fathers age at death was significant in predicting a childs longevity.
-Intelligence predictors were significant.
-Three socioeconomic predictors, education, finances, and occupation were positively correlated with longevity.
-The following activity factors were significant:
  • Locomotor activities (physical mobility)
  • Secondary activity (number of organizations the person was a member of, time spent reading, number of meetings attended, leisure activities)
  • Nongroup activity (daily hobbies)
-Three sexual relations indicators were significant, including the frequency: of intercourse per week, the past enjoyment of intercourse in younger years, and the current pleasure of intercourse.
-Tobacco use was a significant negative predictor.
-Work satisfaction, religious satisfaction, usefulness and happiness were all positively correlated with a long life.
-Three health predictors were significantly linked to longevity:
  • Physical functions rating based on objective health indices, i.e. ECG, audiogram, physical exam, etc.
  • Self rating of the persons own health status
  • Health Satisfaction Score based on agreement/disagreement with 6 statements

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Hryhory Nestor, 114, Ukraine

Other studies are currently underway which are reporting amazing results in increasing, and in some cases, doubling the longevity of animals in experimental environments. For instance, rats that have had their food intake cut by 40% can live a very long life, even doubling their average life expectancy. To top this off, these animals are amazingly free of diabetes, cancer, and heart disease! When they do get these diseases, they are much delayed when compared to animals who eat all they want. Human studies are currently underway. In fact, the noted anti-aging expert Dr. Walford is a strong proponent of calorie restriction as a method to increasing human life.

Another promising experiment which has been popular with the public was the Biosphere Project. From 1991 to 1993, 8 men and women were locked way from the rest of the world, having to grow every bite of food, generate their own air supply and recycle all their water in this environment. Problems arose when they ran low on food. As the Biosphere team members ate less, their body statistics changed. The men lost an average of 18 percent body weight, the women 10 percent. Blood pressure fell on the average by 20%. Indicators for diabetes, such as blood sugar and insulin levels, decreased by 30 percent on average. Cholesterol level also dropped. These statistics are interesting because they are numbers associated with much younger persons than were the members of the Biosphere team.

It looks like, it is almost impossible to reach and bypass the pre-set lifespan for humans of 120 years, however, you have a chance to get closer to the magic age. We are not only getting the longevity predisposition with our genes from our parents, but we have certain power to affect it by our lifestyle habits. It does make sense that living healthy and happy life helps to extend our years on the Earth.

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