Scientists Uncertain About Reasons People are Living Longer
San Francisco, CA -- (SBWIRE) -- 10/23/2012 -- New research indicates that, since people in developing countries are living more than twice as long as their hunter-gatherer ancestors, 72 is the new 30.
The vast decline in early mortality has occurred over the last century, said authors of a recent study on aging.
"I still can't believe how recent most of the progress is," said Oskar Burger, lead author of a study published online in Proceedings of the National Academy of Sciences.
Burger added that our estimates on the limits of human life spans may be too low.
The study findings "make it seem unlikely that there is a looming wall of death ... which kills off individuals at a certain age" because of genetic mutations that build up as we age, said Burger, a postdoctoral fellow at Max Planck Institute for Demographic Research in Rostock, Germany.
In analyzing mortality rates in the West today, as well as those of prehistoric hunter-gatherers, “we show that human mortality has decreased so substantially that the difference between hunter-gatherers and today's lowest-mortality populations is greater than the difference between hunter-gatherers and wild chimpanzees," the researchers wrote.
For instance, human hunter-gatherers were roughly 100 times more likely to die before age 15 than modern residents of Sweden and Japan. The study indicates hunter-gatherers were as likely to die as 72-year-old Japanese people.
Still, the human lifespan did not increase over thousands of years. Rather, it surged ahead after 1900 in what study authors refer to as a "rapid revolutionary leap."
But why are people living longer? "Certainly clean water, better shelter, food and medicine all make a difference," Burger said. He added, however, that determining which had the most impact and when is difficult to determine.
Research contradicts the notion that genetic mutations over time prevent humans from living longer, said Burger. Adding, "Without changing our genetic code at all, we have all of this improvement in mortality at these ages where these mutations should kill us off. And we got all this improvement without 'fixing' any of these mutations that are predicted to cause our bodies to break down in various ways."
Other experts do not necessarily agree. Ronald Lee, director of the Center on Economics and Demography of Aging at the University of California, Berkeley, said the findings of the recent study do not challenge current scientific wisdom regarding the human lifespan. Modern mortality rates do not “seem inconsistent with the theories, given the great improvements in medicine, water quality, sewage disposal, nutrition, control of violence and accidents," he said. He added, that "we still do not know the limits, if any, to the improvements in human longevity that have been occurring rapidly and steadily over the past two centuries.”
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