Humans appear not to have a maximum age, though lifespan has to this point capped at around 97 years. That comes, however, with "a twist that gives us hope for more," according to an article by Johannes Koettl for the Brookings Institution.
"The question arises," writes Koettl, a senior economist for the World Bank, "will this past trend continue forever, allowing future generations to live at some point to the age of 150 years and even beyond? Or is there some limit to increases in life expectancy — an upper bound that humankind won't be able to cross?"
It's a question that's been asked for years and in different ways, but that boils done to: How much time can mankind squeeze out of a human body and what might increase that life duration?
A brand new study from the Academy of Finland published in Nature says that aerobic capacity is tied to lifespan, which in background material it calls a combination of "genetic background and physical activity."
The Finnish researchers note that "Observational follow-up studies report a strong relationship between high physical activity level and long lifespan. In addition, animal tests have shown that high genetic aerobic capacity is associated with health and longevity even without endurance training." In contrast, they write, "Low aerobic capacity in turn is linked to overweight, metabolic and cardiovascular risk factors and shortened lifespan. Previous studies have shown that physically active individuals are healthier and have longer lifespan compared to their sedentary counterparts. However, physical activity level differs substantially between individuals partly due to genetic factors."
They looked at physical activity in lab animals and then in human twins, where one is more physically active and the other more naturally sedentary. In non-identical twins, they found an association between a lot of physical activity and longer lifespan. In identical twins, they did not see a difference in lifespan if one was active versus not active. That showed that genetic background impacted activity level, they said.
When they tried to tease genetics out of the physical activity question, they noted that just "vigorous" physical activity didn't turn into longer lifespans, although it's clearly good for the quality of one's life and health.
"Based on both our animal and human findings," they wrote, "we propose that genetic factors might partly explain the frequently observed associations between high physical activity level and later reduced mortality in humans."
Koettl explores the question in a different way, noting the "compensation effect of mortality," which says that medical advances help us to outlive various illnesses, such as infections, but those who live into old age will deteriorate more at the end. And "the healthier we are as young people, the faster we will age when we are old."
The big change is that medicine has been "manufacturing our lifespan" so more people are living longer.
"Overall improvements in health systems make us all much healthier as young people, but the compensation effect of mortality ensures that the healthier we are, the faster we will age towards the end. Somehow, nature has equipped our species with an intrinsic rate of bodily decay that will allow only few of us to live beyond 97," writes Koettl.
Despite the seeming limit, the fact that "somehow we found a way to slow down the process of bodily decay that was given to us by nature" is a "truly remarkable development that no other species has achieved before," he said.
Lifespan has been debated for a very long time.
More than a decade ago, three experts on old age discussed over lunch in Chicago what a better human design would be if living longer was the primary design goal. Robert Butler was the president of the International Longevity Center in New York City. Bruce A. Carnes and S. Jay Olshansky were both senior research scientists at the Center on Aging at the University of Chicago.
The three men came up with a design for a "built to last" person that looked more like a "muscular elf" than the typical human, they told the Deseret News. It would have bigger and more mobile ears, the knees would bend backward to eliminate grinding and good posture would not be desirable. Instead, we'd walk somewhat tilted forward. The internal changes were significant. Their long life "by design" was published in Scientific American and updated this year (paywall).
Their suggestions warned that "the single-minded pursuit of life extension could actually be harmful to our species' long-term survival."
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