100 is a fancy number. Human beings are supposed to live for hundred years.
Let us assume that the current average life expectency for the entire world population is X. X’s value must have been much less during the early years of civilization and as human beings learnt to fight against diseases and illnesses, its value must have gone up, and I guess it still is going up, although rather slowly. So a function of X vs. time should ideally be an increasing function.
Statistics supports this argument. Current value of global life expectency is 67 years while it is estimated at just 30 years two centuries ago[1]. What can be concluded from such a trend is that, in general, human beings have been putting in their best effort to push up the value of X. In general, every human being wants to live as long as he/she can. 100 is the emprically established standard target. But is such a personal desire, really desirable from the point of view of society as a whole? Does the society benefit if more and more people strive to living longer?
A rich person will usually have a higher life expectency. So will a rich country. In other words there should be a positive correlation between a country’s GDP per capita and life expectency. This relationship can be exploited to state that, society does benefit, if on an average, people live longer. But frankly speaking, it’s increasing wealth that leads to longer life. It is quite possible to be rich even with a lower life expectency.
I think it is time we stop thinking beyond 100 and figure out, how long we really need to live. Is it possible to make the world more productive by changing the trend of X externally? If I were to play God and decide how long a human being should live, what number would I pick?
References:
1. James C. Riley, Rising Life Expectancy: A Global History. New York: Cambridge University Press, 2001 (link)