Anti aging guide

Why do populations age?

 

 

The 2 main factors that influence the age structure of a population when it comes to aging

It is a common misconception that the credit-or the blame-for the rising tide of older people can be laid at the door of the medical profession. In point of fact, so-called curative medicine makes extremely little impact upon the longevity of a population. The incidence of tuberculosis in the United Kingdom, for example, was rapidly declining long before the advent of effective chemotherapy. Despite modern drugs and surgical techniques, the expectation of life of a 65-year-old Englishman was only just over 3.5 years longer in 1982-3 than it had been 90 years previously. His wife, it is true, had fared somewhat better, and the figures in the USA are comparable at age 60 – a further 22 years for a woman, a further 17 for a man. This is in contrast to the dramatic transformation in the life expectancy at birth which occurred between those dates.

There are two main factors which influence the age structure of a population – its fertility, or birth-rate, and its infant and childhood mortality.

Birth rate

To state the obvious, the more live births per female, the higher the proportion of young people in the community. Birth-rates fluctuate a great deal over the years. The end of the seventeenth century was a period of fertility in Great Britain, and as a consequence, early in the eighteenth century more than ten per cent of the population was aged over 60, a figure which then declined to 6.5 or 7 per cent and remained there until the present century. There was a marked decline in fertility in this country after about 1870, and a further fall during the first third of this century. Fertility rates have dropped again in European countries since 1964-65. The French have calculated that each woman needs to bear 2.2 children simply to replace the generations, but with characteristic capriciousness each Frenchwoman is currently only producing 1.96 babies. The birth-rate in that country fell from about 17 per 1000 inhabitants in 1971 to 14 in 1978: the birth rate in the USA in 1980 was 15 per 1000. By way of contrast, a number of the developing nations have birth-rates over 40 per 1000 (for example Bangladesh, Pakistan, and Paraguay) which is sufficient to double their numbers in 35 or 40 years. The birth-rate in Kenya is 53 per 1000. These countries are all likely to continue to have a demographic structure heavily dominated by the young.

Decrease in child and infant mortality

Whatever one’s view about the desirability of a falling birth-rate, the second factor which leads to a relative growth in the proportion of elderly people in the population is an unmitigated blessing. It is the enormous reduction in infant and childhood mortality in the UK and other developed nations over the past 75 years or so. This is mainly a result of the virtual elimination of the infectious diseases as a cause of death – an advance which owes more to improved standards of housing, heating, nutrition, and sanitation, than to medical treatment. At the end of the eighteenth century, 50 out of 100 children died before their tenth birthdays and only six lived to be 60. As recently as the First World War, the infant mortality rate in the UK claimed more lives than the carnage of the trenches. In the affluent countries, this situation has completely changed, so that sickness and death are increasingly the preserves of older people – the tricks that fate keeps up her sleeve until you reach the age of 60 or 65. However, this happy state of affairs is far from universal, and throughout the world, millions of people are exposed to conditions such as malaria, bilharzias, malnutrition, and AIDS which show scant respect for the vitality of youth. Just 15 years ago it was true that in Africa, Asia, and Latin America, half of all deaths occurred in children under five. In most parts of these continents, this appalling toll has since then been drastically reduced.

Posted by Carol Hudgens - March 24, 2012 at 6:00 pm