How long should we live? An accepted formula for calculating this, in mammals, is based on the multiplication by five of the time it takes the skeleton to mature. Thus because a dog's growing period is three years, its life span average is considered to be fifteen years. Human skeletal growth is complete by age 25 and so a fair estimate of our life expectancy is around 120 to 125 years. Anyone failing to get close to this is losing a good number of potentially happy and productive years.
If, then, our natural ceiling is about 120 years, beyond which human life is unlikely, we should ask why so few of us come anywhere near that age, and why those who do are usually in an advanced state of decrepitude. Infirmity and disability are not attractive prospects, so why should the aim of a longer life be an attractive idea? Simply because it is not the aim of those promoting life extension to help us towards that 120 year barrier in anything other than a reasonable state of well-being.
Professor Leonard Hayflick of the University of California, San Francisco, is quoted as calling this search 'the last great biological frontier' ('The Fountain of Youth', Newsweek, 5 March 1990, page 34). In fact the quest has been summed up quite neatly by another Californian, Professor Edward Schneider (University of Southern California) for it was he who said 'We are trying to add life to years rather than years to life.'
In fact both aims are synonymous and should be equally vigorously pursued, for if quality of life, including vitality, vigour and lack of chronic disease could be achieved, it is almost certain that life expectancy would increase.
Expect to live longer by living longer
Any boy born in the US or UK in 1990 can expect to live just over 76 years, while a girl can look forward to 83 years of life.
The older you get the longer your life expectancy becomes. For example, if you are now 25 your life expectancy at birth was 72.7 if you are male and 80.6 if you are female. However, your life expectancy now is 76.2 years (male) and 83.1 (female). Since birth your life expectancy has increased by 2 to 3 years. This increase in life expectancy is even more dramatic for people who are now older than 25, as follows:
| Life expectancy at birth | Life expectancy today |
| Age now | male | female | male | female |
| 45 | 70.4 | 77.9 | 77.3 | 82.8 |
| 65 | 64.1 | 71.9 | 80.6 | 84.9 |
| 85 | 54 | 61.4 | 90.5 | 91.9 |
(Figures based on the US Office of the Actuary, Social Security Administration)
The longer you stay alive the longer you can expect to live, seems to be the message. But not even the longest of these 'expectancies' approaches our true biological potential, and life extension methods are aimed at redressing that shortfall, rather than actually altering the ground-rules.
The immediate prospect of living to well over 100 may not be attractive, especially if you hold the idea of advanced age alongside an image of physical and mental decline. However, Prolonged life would be a much more attractive prospect were it linked to an almost assured state of mental and physical wellbeing and fitness. This is the aim of natural life extension. Long life is not just seen as an end in itself, but rather has as its objective a state of excellence in health which will bring enjoyment to long life.