This blog is intended to go along with Population: An Introduction to Concepts and Issues, by John R. Weeks, published by Cengage Learning. The latest edition is the 12th (it came out in 2015), but this blog is meant to complement any edition of the book by showing the way in which demographic issues are regularly in the news.

If you are a user of my textbook and would like to suggest a blog post idea, please email me at: john.weeks@sdsu.edu

Thursday, July 5, 2018

Could We Live Forever?

Thanks to Todd Gardner and others for pointing to a research article published this week in Science on the "Demography of Longevity Pioneers." The researchers, who included James Vaupel of the Max Planck Institute for Demographic Research in Germany and Ken Wachter of the UC, Berkeley Department of Demography, used data from older Italians. This had the advantage of choosing a population in which a fairly large number of people have survived to the oldest ages, and using data from a single data source, thus reducing the problem of comparing data collected in different ways. Their findings suggest that while death rates continue to climb up to age 105, after that they are constant, with about a 50% chance of survival each year beyond 105.

Nature picked up on the story and invited comments from people not involved in the study:
If there is a mortality plateau, then there is no limit to human longevity,” says Jean-Marie Robine, a demographer at the French Institute of Health and Medical Research in Montpellier, who was not involved in the study. That would mean that someone like Chiyo Miyako, the Japanese great-great-great-grandmother who, at 117, is the world’s oldest known person, could live for years to come — or even forever, at least hypothetically.
That would fit into the theory of longevity promoted by people like Elmo Keep, a science entrepreneur in the Silicon Valley, as I blogged about last year. On the other hand, not everyone thinks we should yet jump to these big conclusions:
Brandon Milholland, a co-author of the 2016 Nature paper, says that the evidence for a mortality plateau is “marginal”, as the study included fewer than 100 people who lived to 110 or beyond. Leonid Gavrilov, a longevity researcher at the University of Chicago in Illinois, notes that even small inaccuracies in the Italian longevity records could lead to a spurious conclusion.
Others say the conclusions of the study are biologically implausible. “You run into basic limitations imposed by body design,” says Jay Olshansky, a bio-demographer at the University of Illinois at Chicago, noting that cells that do not replicate, such as neurons, will continue to wither and die as a person ages, placing upper boundaries on humans' natural lifespan.
Only time will tell which conclusion is correct, of course. In the meantime, the number of old-old people is increasing in the world, so we'll have a consistently larger population from which to derive data. 

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