The Plasticity of Life Span

We live longer than our ancestors thanks to our greater wealth and more advanced technology: risk of death is reduced at all ages, the level of damage suffered due to infectious disease and other causes is lowered throughout life, and inroads made into means of alleviating age-related disease. When it comes to effects across a life span, however, our extended lives are so far largely incidental, a side effect of improvements in medicine and quality of life that were introduced to satisfy other, more short-term goals.

This shows that aging and life span is very plastic - it can be changed, and is very readily changed. On the other hand, it tells us next to nothing about what lies ahead, as the rejuvenation biotechnology of the future will be an entirely different beast from the medicine of the past. Only now is the research community deliberately trying to manipulate the processes of aging, or repair the biological damage that causes degeneration. Given this shift in what is possible, projecting past trends to the future is unwise: the deliberately engineered changes in longevity of tomorrow will not look like the incidental benefits that slowed aging yesterday.

Here is an article on recent research that seeks to quantify the degree of improvement in human life expectancy that has occurred in recent centuries - you might want to look at the paper itself since it is open access.

It's said that life is short. But people living in developed countries typically survive more than twice as long as their hunter-gatherer ancestors did, making 72 the new 30, according to new research. Most of the decline in early mortality has occurred in the past century, or four generations, a finding that calls into question traditional theories about aging.

But there's a larger message from the research: Our estimates about the limits of human lifespans 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.

For example, hunter-gatherer humans were about 100 times more likely to die before age 15 than today's residents of Japan and Sweden. And the study says hunter-gatherers were as likely to die at age 30 as Japanese people are at age 72. But the human lifespan didn't grow gradually over thousands of years. The big jump occurred after 1900 in what the study authors call a "rapid revolutionary leap."

In the big picture, the research challenges the idea that genetic mutations over a lifetime prevent humans from living very long ... 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.



This, in particular the quote at the end, is silly - and you should know better. The final sentence, 'And we got all this improvement without 'fixing' any of these mutations' carries with it the implication that future extension of lifespan is dependent on an extension of previous methods. You know this is not true - most of the increase in longevity in the 20th century occurred through nutritional improvement, antibiotics - aka, the easy stuff. To radically extend life now you need to attack the root causes of aging.

Posted by: Leon at October 17th, 2012 12:26 PM

@Leon: The point of interest is inherent plasticity of aging in response to changing quality of life and past medical technology. It is something to remark upon in much the same way as the effects of calorie restriction - a sign that the biology of aging is more flexible than was thought up until fairly recently.

Yes, it has little to no importance to the future of rejuvenation, which must approach engineering of longevity in a more direct and repair-based way if it is to be successful. But that as not the way the mainstream of the research community presently sees things: they are very much in line with following the plasticity we see in the pace of aging, and pushing it as far as it will go to achieve modest benefits. Hence much of the news echoes that view.

Posted by: Reason at October 17th, 2012 1:23 PM

Hello, I like to believe that it may be possible to someday reverse aging in humans but seems like we are extremely far away from making it happen. I mean we can't even find a cure for male baldness, and that seems like it would happen first. Honestly pretty much everything ages, planets, universe, earth, animals, except the few such as jelly fish, and lobsters perhaps. I try and be optimistic but I think we may become cyborgs before we are capable of reversing aging. Sorry it's off topic.

Posted by: Person at October 17th, 2012 5:18 PM

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