Disagreements on the Current Trajectory of Life Expectancy

Here is another article in a popular science series on the history of human longevity and related topics. This looks at a mainstream disagreement in aging research, among researchers who do not see radical life extension as a near-term possibility:

One of the most fascinating debates in life science these days is between S. Jay Olshansky and James Vaupel of the Max Planck Institute for Demographic Research in Rostock, Germany. They disagree fundamentally about whether and how average life expectancy will increase in the future, and they've been arguing about it for 20 years. Olshansky, a lovely guy, takes what at first sounds like the pessimistic view. He says the public health measures that raised life expectancy so dramatically from the late 1800s to today have done about as much as they can. We now have a much older population, dying of age-related diseases, and any improvements in treatment will add only incrementally to average life expectancy, and with vanishing returns.

On the other side of the ring is Vaupel, who says that people are living longer and healthier lives all the time and there is no necessary end in sight. His message is cheerier, but he takes the debate very seriously; he won't attend conferences where Olshansky is present. His charts are heartening; he takes the records of the longest-lived people in the longest-lived countries for each year and shows that maximum lifespan has been zooming up linearly from 1800 to today. One wants to mentally extend the line into all of our foreseeable futures.

Olshansky says the only way to make major improvements in life expectancy is to find new ways to prevent and treat the diseases of aging. And the most efficient way to do that is to delay the process of aging itself. That's something that some people already do - somehow. Olshansky says, "The study of the genetics of long-lived people, I think, is going to be the breakthrough technology." Scientists can now easily extend lifespan in flies, worms, and mice, and there's a lot of exciting research on genetic pathways in humans that might slow down the aging process and presumably protect us from the age-related diseases that kill most people today. "The secret to longer lives is contained in our own genomes," Olshansky says.

Olshansky favors the mainstream high level research strategy that I believe is largely futile: a slow, expensive process of building treatments to alter human metabolism to look more like that of long-lived people, or replicate the effects of calorie restriction. It will produce a great deal of knowledge, but little effect on life spans: this is an approach that will slow aging slightly, not create rejuvenation, and not directly address the root causes of aging. If we want to see real progress in human life span in our lifetimes, decades or more of healthy life added even for those already old, then we have to back repair-based research such as the Strategies for Engineered Negligible Senescence (SENS).

Link: http://www.slate.com/articles/health_and_science/science_of_longevity/2013/09/maximum_adult_lifespan_debate_over_how_long_humans_can_live.single.html


While I agree that Olshansky's research strategy is probably largely futile, Vaupel's "heartening charts" don't sound on the level to me. If you're only looking at the most extreme cases over time, they are naturally going to get more and more extreme as the world population grows, just as a result of probability theory. If something (such as living to age X) only has a 0.001% chance of happening to somebody, you wouldn't expect anyone in a group of 100 people to live to age X, but in a group of 7 billion people you'd expect around 70,000 people in the group to live to age X.

Posted by: fm at September 19th, 2013 8:29 AM

I'm not entirely sure that metabolic tweaking is hopeless. It is very likely that negligible senescence species mostly have this. There have been some drugs that have resulted in vast clearance of misfolded proteins from the brain of mice showing that some natural clearing mechanism must be present that can be revved up.

We know that in some cells such as neurons the cell does not divide yet it has been seen that its lifespan can exceed that of its original species lifespan(mice to rat neuron transplant study). And neurons have lasted ever more with what seems like only metabolic tweaking, in some species lasting multiple centuries.

Humans enjoy a very long lifespan, showing that we've evolved at least part-way towards negligible senescence, the question is how many more steps would be needed to reach negligible senescence and what would this involve in addition to metabolic tweaking.

Posted by: dsmith at September 22nd, 2013 4:36 PM

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