Methuselah's planet: the population cost of longer life

Ageing is a mysterious process. There is a good deal of ongoing research aimed at trying to understand its biological cause, though much remains unknown. Some research is aimed at trying to unlock longevity, for example a study published this week that found a particular gene mutation in a group of long-living Ashkenazi Jews. Other researchers are actively looking at rare diseases like progeria which lead to accelerated ageing. It is often expressed that such research will make it possible to extend the normal human lifespan.

But should we try to make our lives longer? In an era of increasing environmental awareness, when the costs of human overpopulation are all too clear it might be argued that the planet cannot support a significant increase in our lifespan.

It is generally accepted that there are finite resources on Earth. The world human population stands at approximately 6.7 billion, and will probably reach 8 billion by 2020. Providing food, fresh water and energy for the growing population is an enormous challenge. Future technologies may dramatically change our use of natural resources, and may change the number of our species that can be sustainably supported. However at present, recognition of limited resources is one important reason for efforts to reduce population growth.

However if anti-ageing science delivers an increase in human lifespan this would have dramatic effects in increasing the world population, counteracting substantially efforts to curb growth. One estimate is that instead of 8 billion, world population would reach 10 or 11 billion by 2030.

From this point of view it may be irrational to attempt to increase our lifespan while at the same time striving to curb population growth. Furthermore it might be thought that such research reflects a double standard in relation to population. Whereas population growth occurs largely in developing countries, measures to increase lifespan are likely to be available (at least initially) only in Western, developed countries.

If an anti-ageing pill were available today that increased the length of our lives (without simply leading to longer periods of ill-health and dependence) most of us would jump at the opportunity to take it. Yet the environmental costs of such a development might outweigh all of our attempts to save energy, recycle paper, reduce air miles. There would be a strong argument for not making such a pill available at all.

Links

Too Old Too Fast Science News 3/3/08

Scaffidi P, Mistelli T. Lamin A-dependent misregulation of adult stem cells associated with accelerated ageing. Nature Cell Biology 2008

“Methuselah” mutation linked to longer life Scientific American 4/3/08

Suh, Y et al Functionally significant insulin-like growth factor I receptor mutations in centenarians. Proc Nat Sci 2008; 105:3438-3442.

World Population Clock

World faces challenge as technologies lengthen life expectancies, biologist says Stanford News Service 2006

Comments

[Wayne Yuen]

I'm not sure if extending one's life is morally impermissible. Extending one's life does not necessarily mean that we will add to a population crisis, if one exists. Assumedly, those who have access to this kind of life extending treatments would be those already in affluent nations, which are not attributing to the population crisis per se (better sad that they are contributing to the scarce resources problem). Not that this makes it morally acceptable, becaue they are affluent.

More to the point, people could take advantage of the life extending treatments and not reproduce, or reproduce later in life, or have fewer children, all of which are true about affluent nations, even without life-extending technology.

The life-extending pill scenario could be amended, so as to stipulate that one would become sterilized permanently if one took the pill, and it would be made available only to those who have not had more than one child (to fight the effects of population inertia, we would have to limit it to one child, rather than self-replacement, two children for each couple).

But more importantly, if we said that giving the life extending pill would be immoral, then we would be hard pressed to say that ANY life-extending technology would be morally acceptable. Anti-biotics would be immoral because they extend people's lives considerably.

I think this issue is very similar to the issue of a young teenaged mother. Most people would say it would be inadvisable for a young teenager to have a child, and so they would encourage abortion. But once the child is born, they would not encourage infanticide. This child is already actualized. Similarly, we are actualized people, and we should take steps to extend our lives as much as we can, but at the same time, we should also take steps to actualize FEWER people.

[Dominic Wilkinson]

there are several ways in which life extension could be made available with entailing the environmental costs that I have implied.
Firstly, as you suggest it could be introduced with simultaneous measures to reduce the birth rate. This raises the interesting question of whether it would be better to have a future world with less people living longer lives, or a world with more people living shorter lives. That might depend upon whether the added years of life gained were at an 'average' level of utility, or lower than average. In any case one reason to be sceptical about this solution to the population problem is that at present our capacity to reduce birth rates at a global level is seriously limited.
Secondly we could introduce life extension, but simultaneously reduce the environmental costs of human population. It might be possible to do this, but again at present we are limited on a global level to attempts to reduce the growth in energy consumption and carbon usage.
Thirdly, extended life might be made available, but only to a limited number of people. As you imply, an individual decision to live longer may not add to a population crisis. However there are serious equity implications if longer life can only be available for a few. Who should be allowed to live longer? Should it only be an option for the rich?
Finally Methuselah-length life might be supportable if there were changes in energy production/food production such that the planet were able to support a significantly larger population.