Living to 150

The Treasurer of Australia, the Hon Joe Hockey MP, recently received widespread attention with the statement:

It’s kind of remarkable that somewhere in the world today, it’s highly probable that a child has been born who will live to be 150.[1]

Hockey made the claim while discussing some of the problems Australia faces as a result of an ageing population.  While his statement was ridiculed by cartoonists and political rivals, he received support from some in the medical community.  The Dean of Medicine at the University of New South Wales, Peter Smith, described Mr Hockey’s claim as a “reasonable assumption”. Professor Smith noted that life expectancy for Australians has been climbing dramatically over the past 100 years. A boy born between 2010 and 2012 can expect to live to 80 years and a girl can expect to live to 84 years. This is up from 55 and 59 years respectively in 1910.

However the fact that, on average, people have been living longer and longer does not support the claim that there is someone living today who will reach 150. This line of argument confuses increases in life expectancy (the number of years the average human can expect to live) with increases in lifespan (the maximum amount of time a human can live). While life expectancies have been rapidly increasing over the past century, human lifespan has remained more or less the same for the last 100,000 years (at approximately 125).[2]  No human has ever got close to 150 and if someone is alive today who is going to live that long it is going to take different types of developments than those which have increased life expectancy. Rather than just preventing people from dying young, we are going to need methods of altering the ageing process itself.

That is not to say that these developments won’t happen soon. Scientists have long been able to manipulate ageing in other animals. In 1986, scientists showed that restricting the caloric intake of mice increased their lifespan by up to 65%.[3] Since then, caloric restriction has been shown to increase lifespan in a diverse range of species including yeast, fruit flies and dogs. Altering the expression of certain genes also increases lifespan in a range of species, sometimes by as much as 100%.[4] Pharmacological interventions have also been developed that slow the progression of age-related decline in several species.[5]

It has so far proved much harder to extend the lifespan of our own species.  Humans have already evolved to have a long lifespan, due mainly to an unusually long post-reproductive phase of life. The same mechanisms used to increase lifespan in short-lived species have little impact on human lifespan, or that of other primates.  Hence the fact that we can extend the lifespan of other animals only partially supports the claim that we will soon be able to manipulate human ageing and extend lifespan to 150 years. Significant research effort will be required to reach this milestone.

The most significant consideration favouring lifespans of 150 in the near future term, then, is the fact that there is now a lot of interest in life extension research, both within academia and from well-funded corporations. In late 2013 one of the world’s largest companies, Google,   established a subsidiary called Calico, with the sole focus of investigating ways to combat human ageing.[6]  Similarly Craig Ventor, whose company Celera Genomics was the first to sequence the human genome, recently established Human Longevity Inc, a new company with a focus on enhancing human lifespan.  One research direction these companies are likely to explore involves incorporating nanotechnologies into our cells. Many gerontologists believe that ageing consists solely of a small number of cellular changes, which are potentially preventable and reversible. Once we develop technologies capable of preventing and reversing these changes, we can prevent and reverse ageing.  Google is currently developing nanoparticles which are designed to enter our cells and diagnose disease-related changes as soon as they occur.[7] As these nanoparticles become more sophisticated they might also be able to detect age-related cellular changes, and stop and reverse them.

However, one thing to note about this approach is that it seems likely to increase lifespan far beyond 150. Once we can stop and reverse age-related decline, we may expect very radical increases in both lifespan and life expectancy. This prospect raises a range of very significant ethical issues (one of which I discuss in this paper). It will also pose a much more significant range of political challenges than most politicians would like to consider. While 150 may be a stretch for anyone alive today, Australia’s Treasurer may well be ahead of the times in beginning a conversation about this possibility.

[1] http://www.smh.com.au/federal-politics/political-news/joe-hockeys-comments-on-living-to-150-a-sarah-palin-moment-says-bill-shorten-20150119-12tbvn.html

[2] M. Tosato, et al. The aging process and potential interventions to extend life expectancy. Clin Interv Aging 2007; 2: 401-412.

[3] R. Weindruch. The Retardation of Aging by Caloric Restriction: Studies in Rodents and Primates. Toxicol Pathol 1996; 24: 742-745.

[4] H. R. Warner. Longevity genes: from primitive organisms to humans. Mech Ageing Dev 2005; 126: 235-242.

[5] V. Anisimov. Insulin/IGF-1 signaling pathway driving aging and cancer as a target for pharmacological intervention. Exp Gerontol 2003; 38: 1041-1049.

[6] M. Liedtke. 2013. Google tackles immortality with launch of health company Calico. Sydney Morning Herald 19 September. Available at: www.smh.com.au/technology/technology-news/google-tackles-immortality-with-launch-of-health-company-calico-20130919-2u1fh.html

[7] http://www.bbc.com/news/technology-29802581