Is There a Fixed Mortality Age?

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Is There a Fixed Mortality Age?  

Jim Windell

            Okay, we all know death is inevitable. But…don’t we all think sometimes that by eating right, exercising more, meditating every day or some other health-related or age-related habits might just give us a few more years and delay the appearance of the Grim Reaper? Isn’t there some way to find a fountain of youth that will help us put off the ravages of old age?

            However, you argue, isn’t the mortality age steadily increasing in the U.S.? Won’t most people soon live to be 100 before they die? Doesn’t this mean that there is literally no limit on how long we could potentially live?

            While we could debate this and philosophize about aging and death, a new study finds fresh evidence for our inevitable death.

           A study led by Fernando Colchero, who is at the University of Southern Denmark, and Susan Alberts, who is with Duke University in North Carolina, included researchers from 42 institutions across 14 countries. This study provides new insights into the aging theory "the invariant rate of ageing hypothesis." This theory states that every species has a relatively fixed rate of aging.

           “Human death is inevitable,” says research leader Fernando Colchero. “No matter how many vitamins we take, how healthy our environment is or how much we exercise, we will eventually age and die.”

           Colchero is an expert in applying statistics and mathematics to population biology while serving as associate professor in the Department of Mathematics and Computer Science, University of Southern Denmark.

           In order to explore the hypothesis that every species has a relatively fixed rate of aging, the researchers analyzed the relationship between life expectancy, this is the average age at which individuals die in a population, and lifespan equality, which measures how concentrated deaths are around older ages.

           Their results, published in Nature Communications, show that as life expectancy increases so does lifespan equality. Lifespan equality is very high when most of the individuals in a population tend to die at around the same age, such as what is observed in modern Japan or Sweden. In these two countries, lifespan equality is around 70 or 80. However, in these same countries in the 1800s, lifespan equality was very low because deaths were less concentrated at older ages – resulting also in lower life expectancy.

           Colchero explains it this way: “Life expectancy has increased dramatically and still does in many parts of the world. But this is not because we have slowed our rate of aging; the reason is that more and more infants, children and young people survive and this brings up the average life expectancy.”

          The researchers note that not only humans, but also other primate species exposed to different environments, succeed in living longer by reducing infant and juvenile mortality. “However, this relationship only holds if we reduce early mortality, and not by reducing the rate of ageing,” says Colchero.

           By combining an unprecedented wealth of data and comparing births and deaths patterns on nine human populations with information from 30 non-human primate populations, including gorillas, chimpanzees and baboons living in the wild and in zoos, Colchero and his colleagues were able to explore patterns among humans as well as our closest relatives. Through the use of statistics and mathematics, the authors show that even small changes in the rate of ageing would make a population of, say, baboons, to demographically behave as a population of chimpanzees or even humans.

           “Not all is lost," adds Colchero. “Medical science has advanced at an unprecedented pace, so maybe science might succeed in achieving what evolution could not: to reduce the rate of ageing.”

           To read the original article, find it at:

Fernando Colchero, José Manuel Aburto, Elizabeth A. Archie, Christophe Boesch, Thomas Breuer, Fernando A. Campos, Anthony Collins, Dalia A. Conde, Marina Cords, Catherine Crockford, Melissa Emery Thompson, Linda M. Fedigan, Claudia Fichtel, Milou Groenenberg, Catherine Hobaiter, Peter M. Kappeler, Richard R. Lawler, Rebecca J. Lewis, Zarin P. Machanda, Marie L. Manguette, Martin N. Muller, Craig Packer, Richard J. Parnell, Susan Perry, Anne E. Pusey, Martha M. Robbins, Robert M. Seyfarth, Joan B. Silk, Johanna Staerk, Tara S. Stoinski, Emma J. Stokes, Karen B. Strier, Shirley C. Strum, Jenny Tung, Francisco Villavicencio, Roman M. Wittig, Richard W. Wrangham, Klaus Zuberbühler, James W. Vaupel, Susan C. Alberts. The long lives of primates and the ‘invariant rate of ageing’ hypothesis. Nature Communications, 2021; 12 (1) DOI: 10.1038/s41467-021-23894-3


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