Death, it is argued, is not inevitable. Yet it may be essential for the emergence of civilization.
Highly organized as it is, life is a thermodynamically unlikely state. And death is the victory of the likely over the unlikely.
So we are lucky to be living in the first place! Fortunately for us, 3.5 billion years ago, conditions on Earth and plentiful energy from the Sun conspired to initiate life. Under the blind influence of Darwinian evolution, ever more complex organisms gradually arose, culminating (thus far) in the successful and intelligent, if frequently irrational, species Homo sapiens.
But why didn’t evolution go the whole hog? Why do all higher animals age and die rather than maturing and then remaining indefinitely stable in form and function?
Is death an inevitable property of higher life forms? On the contrary: it is hardly plausible that aging and death conferred any evolutionary advantage. The most likely explanation for senescence is that it is an accidental by-product of an unrelated advantageous feature. According to Thomas Kirkwood’s disposable soma theory*, evolution favoured a physiology that yields maximum fertility and reproductive success in early maturity. The advantage is clear: Due to the constant risk of death by natural disasters, predators, etc., individuals who bear offspring early are more likely to pass on their genes than those reproducing later (or indeed not reproducing, because they have already been devoured, genes and all, by a lion). But the biochemistry that maximises reproductive success in youth is unlikely, so the argument goes, to be simultaneously ideal for a second purpose, namely for the perfect maintenance of a stable, potentially immortal organism. And so it is: our maintenance and repair systems are good, but not good enough to prevent aging, e.g., through the accumulation of DNA damage.
Thus death is an arbitrary and not a necessary result of evolution. It is not a law of nature.
We don’t yet have a recipe to stop aging, but Aubrey de Grey** believes this is only a matter of time. He attributes aging to seven biological processes, all of which medicine may one day be able to avoid or control.
As and when we can prevent death from old age, our lives will change dramatically. But, beyond escaping the problems and pains of senescence, it is not clear that either society or the individual would benefit: Reproduction would need to be strictly controlled, or emigration to other planets organized; our motivation to work, to create, to explore the world, may diminish – why make the effort today, when tomorrow or next century are just as good? Brains would not decay, but their storage capacity would eventually be exhausted. So we could only learn new skills or store new memories by losing older ones.
Finally, suppose evolution had achieved the „no-aging“ trick from the start (as may be the case on other planets), then our ancestors would also have lacked urgency and drive. This could even explain why we have yet to receive signals from alien life forms: They are immortal and haven’t got around to sending any! Our finite lifespan is a prime motor of cultural evolution. Knowledge of our own mortality spurs us to use the time we have: to learn about and improve the world; to make our mark on art, science or society; to help our progeny make their own way in life; to feel that we have not lived in vain.
We will always yearn for eternal life. But without death, our species might never have advanced far enough to even contemplate its own mortality, let alone bring forth culture, technology and social progress. We owe much to the lives of our ancestors … and perhaps more yet to their deaths.
* T. Kirkwood, Evolution of ageing. 1977. Nature 170 (5635) 201
** A. de Grey, M. Rae, Ending Aging (St. Martin’s Press, New York 2007)Angela Lahee