We cannot cheat aging and death, study indicates
University
of Southern Denmark
A study led by Fernando Colchero, University of Southern Denmark and Susan Alberts, Duke University, North Carolina, that included researchers from 42 institutions across 14 countries, provides new insights into the aging theory "the invariant rate of ageing hypothesis," which states that every species has a relatively fixed rate of aging.
"Human
death is inevitable. No matter how many vitamins we take, how healthy our
environment is or how much we exercise, we will eventually age and die,"
said Fernando Colchero.
He is an expert in applying statistics and mathematics to population biology and an associate professor at Department of Mathematics and Computer Science, University of Southern Denmark.
"We were
able to shed light on the invariant rate of ageing hypothesis by combining an
unpresented 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,"
said Fernando Colchero.
In order to
explore this hypothesis, 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
show that, as life expectancy increases, so does lifespan equality. So,
lifespan equality is very high when most of the individuals in a population
tend to die at around the same age such as observed in modern Japan or Sweden
-- which is around their 70s or 80s. However, in the 1800s lifespan equality
was very low in those same countries, since deaths were less concentrated at
old ages, resulting also in lower life expectancy.
"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," said Fernando Colchero.
Previous
research from some of the authors of the study has unraveled the striking
regularity between life expectancy and lifespan equality among human
populations, from pre-industrial European countries, hunter gatherers, to
modern industrialize countries.
However, by
exploring these patterns among our closest relatives, this study shows that
this pattern might be universal among primates, while it provides unique
insights into the mechanisms that produce it.
"We observe
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," said Fernando Colchero.
Using 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," says Fernando 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."
This work was supported by National Institute of Aging, Max Planck Institute of Demographic Research and the Duke University Population Research Institute.