There is no such thing as aging

Taking all diseases together (but ignoring deaths from accidents or violence), the total death rate in developed countries such as Britain is 500 times greater at age 80 than at age 20. For vascular disease, chronic respiratory disease, and cancers of the digestive or respiratory tract, this ratio is more than 1000 to 1. Why? What biological mechanisms account for this vast difference in mortality between old and young adults? And, since so many major diseases are much more common in old than in young adults, does this imply that there must be some common biological process called “aging” that causes all of these large differences in mortality? Our answer, particularly for cancer, is that it need not do so.1

What the major diseases of adult life have shared for tens of millions of years is a common set of evolutionary pressures tending to relegate them to old age, but such relegation is likely to involve many different mechanisms. Natural selection acts much more strongly against death in early adult life than against death in old age. Hence, other things being equal, all major adult diseases will tend to be much commoner in old age than in early adult life.

Before asking whether “aging itself” has any direct effects on the development of disease, it may be useful to consider whether there is any fundamental biological process that can usefully be labelled aging. If so, what is it? Is it …