Science is once again casting doubt on the idea that we could live to be nearly as old as the biblical Methuselah or Mel Brooks' famous 2,000-year-old man.
New research from Singapore-base biotech company Gero looks at how well the human body bounces back from disease, accidents or just about anything else that puts stress on its systems. This basic resilience declines as people age, with an 80-year-old requiring three times as long to recover from stresses as a 40-year-old on average.
This should make sense if you've ever known an elderly person who has taken a nasty fall. Recovery from such a spill can be lif- threatening for a particularly frail person, whereas a similar fall might put a person half as old out of commission for just a short time and teenagers might simply dust themselves off and keep going.
Extrapolate this decline further, and human body resilience is completely gone at some age between 120 and 150, according to new analysis performed by the researchers. In other words, at some point your body loses all ability to recover from pretty much any potential stressor.
The researchers arrived at this conclusion by looking at health data for large groups from the US, the UK and Russia. They looked at blood cell counts as well as step counts recorded by wearables. As people experienced different stressors, fluctuations in blood cell and step counts showed that recovery time grew longer as individuals grew older.
"Aging in humans exhibits universal features common to complex systems operating on the brink of disintegration," Peter Fedichev, co-founder and CEO of Gero, said in a statement.
The new research contains a certain amount of validation for the idea that humans start dying from the moment we're born, but the process seems to speed up significantly somewhere in the mid-thirties to mid-forties when the body's resilience starts to decline more steeply.
The study's conclusion that the body loses all ability to cope -- or at least to recover -- from stress before age 150 is line with the conclusions of similar studies, including one from last year that pegged the maximum possible human age at 138 years.
"This work ... explains why even most effective prevention and treatment of age-related diseases could only improve the average but not the maximal lifespan unless true antiaging therapies have been developed," adds co-author Andrei Gudkov, from the Roswell Park Comprehensive Cancer Center in Buffalo, New York.
This is the hope of the researchers -- that it might light the way when it comes to not only maximizing life span, but also a higher quality of life across that span.
"The investigation shows that recovery rate is an important signature of aging that can guide the development of drugs to slow the process and extend health span," said David Sinclair, a Harvard Medical School professor of genetics.
The full study is published and available to the public in the open journal Nature Communications.