From NPR:
Human life expectancy increases at a rate of about two years per decade — or roughly five hours a day. Some scientists think it's possible to live for 500 or even 1,000 years. But if we could live that long, would we want to? In his book, Long For This World, Jonathan Weiner, 56, explores the possibilities for immortality. He tells NPR's Neal Conan that many gerontologists — specialists who study aging — hate the word immortality. “It suggests this kind of supernatural aura that goes all the way back to Adam and Eve,” he says. Still, Weiner says many mainstream gerontologists are talking about work that's essentially the same as those on the fringe who embrace the term. “From where I sit, it's very similar,” he says.
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Why do our bodies stop renewing themselves after about the age of 12? Weiner says the answer to that question lies in evolutionary biology. “It was important for us to build sturdy bodies that will last until we reach the age of reproduction,” he says. According to Weiner, you're on the upswing until about the age of 20. After that, once you pass the age of reproduction and young parenthood, he says, “evolution by natural selection really ignores you. You're disposable, in some sense, because you've passed on your genes.” Weiner says that's why “we aren't built to last.” So, what is possible? In the foreseeable future Weiner says we could gain extra decades — good decades — of life without disease and infirmity. Weiner says that many people around his age are starting to consider what to do with all that extra time. “Since we have a longer lifespan, and a longer healthy life expectancy,” he says, “maybe we can add another chapter.” According to Weiner, that attitude is bound to get more popular as life expectancies increase.
Excerpt: 'Long For This World' here.