Demographers explore key factors contributing to a longer lifespan

Death has been postponed in most highly developed countries in the world. James W. Vaupel's research review shows that the reasons are not mainly genetic. Prosperity, education and medical treatment play a more decisive role.

During the last few decades life expectancy has risen significantly. Today, people tend not only to live around ten years longer than the previous generation, but they also stay healthier for longer. This trend may continue in the future. There are several reasons that could explain this phenomenon, although the puzzle has not yet been completely solved.

Prosperity as a main factor

Vaupel says that prosperity and medicine play the most important role in the longevity of a population. Developed countries are able to invest in expensive research for new medicine, and they can offer good health systems with innovative treatments, even if these are costly. If people are provided with high-quality housing, wear appropriate clothing, eat healthy food and are able to enjoy their lives, they have a better chance of reaching old age. Good treatment does not necessarily reduce mortality at old age, but it does help to minimise disability.

Education is also a factor. Well-educated people are more likely to live longer, because they know more about healthy lifestyles. If, on the other hand, people smoke, do not exercise or are grossly obese, they have little chance of becoming very old. Yet more than the personal behaviour it is the general level of prosperity which matters. Countries which invest in good education, effective medical provision and a healthy environment will improve the chances for the longevity of their population.

Do genes for old age exist?

Some people think that they can only reach old age themselves if their ancestors were long-lived, but are genes really an important predictor? Vaupel has examined research results and has come to the conclusion that, even though it seems likely that many genes play a small role in long life spans, they have just a modest impact overall. He bases this argument on recent results by a research team which looked at genetic influences on human life spans and longevity. In a study of Danish identical twins born since 1890, the researchers found no evidence for maximum lifespan. According to the researchers only about 25 percent of the variation in lifespan is likely to be caused by genes.

Is lifespan limited?

When mortality is delayed one might think that this is caused by a slowing down of the ageing process during the last phase of life. However, this seems not to be the case. Rather it is the onset of deterioration which occurs later. Vaupel points out that the level of mortality and the state of health which used to prevail at age 70 now occurs at 80. This finding was initially a source of surprise for demographers and actuaries and has caused ongoing discussions. If people are continuing to become older by a rate of 2.5 years each decade, and if more and more people are becoming centenarians, will this postponement of death and ageing ever stop? Vaupel suggests the possibility that the delay could continue without a limit set by biology. However this is not certain. More research on further reasons for longevity continues to be carried out.

About the article

Writer: Katrin Schaar (ks), Written for Population Europe

 

Source

Vaupel, James W. (2010): Biodemography of human ageing. In: Nature (424), S. 536–542.