When, and why, must we die? - Phys.org

1 when , and why , must we die?7 October 2016, by Melissa Healy, Los Angeles Times Credit: Peter Griffin/public domainLife-extension zealots have championed manystrategies aimed at prolonging our days here onEarth, and not all sound like much fun (I'm thinkingspecifically about caloric restriction).Supercentenarians - those rare humans who livebeyond the age of 110 - by contrast seem toembrace much more appealing life-extensionstrategies: They routinely endorse regular naps,consumption of large quantities of chocolate, and adaily nip of strong drink, for instance. In short, when it comes to living longer, mysteriesabound. The question is not just how to do it, butwhether, even if scientists could distill the fountainof youth, there is a limit to how long humans couldbe made to new study offers a tentative answer to the latterquestion.

2 Writing in the journal Nature onWednesday, researchers at the Albert EinsteinCollege of Medicine in New York City conducted acomplex statistical calculation and concluded thatthere is such a by geneticist Jan Vijg, the team asserts thathumans who have walked among us have hit thatlimit. And they calculate that if we could cobbletogether 10,000 people who had reached the age of110 (a big and theoretical if), the statisticallikelihood that just one of them would live beyond125 in any given year would be 1 in 10, odds, 1997, the longest-lived human ever recorded - a122-year-old Frenchwoman named JeanneCalment - died, reportedly with her mental facultiesstill intact. Attributing her long life to a diet rich inolive oil, port wine and chocolate, Calment was theonly person whose age, at death, was verified tohave exceeded , at 116, an Italian woman named EmmaMorano is the oldest known person alive.

3 At 113and 111, respectively, Americans Adele Dunlapand Agnes Fenton (both living in New Jersey) arenot far reach this point, all of those women (and yes,supercentenarians are overwhelmingly women)have made it out of infancy, fought off dangerousinfections, survived childbirth and eluded the deadlytalons of heart disease, cancer and eventually, they will all die of something. Why?Probably, the authors suggest, because if nothingelse gets us, some structural limit of our designsimply becomes our of Illinois demographer and agingresearcher S. Jay Olshansky must die eventually, he suggests, becausehumans have a body design that evolved to hang inthere long enough for us to live long enough toreproduce, ensuring the survival of the we've accomplished that, he suggests, naturehas been spectacularly indifferent to parts that wearout, electrical currents that short-circuit, and cellsthat act on bad information and replicate like bodies, in short, did not evolve to live into 1 / 3 extreme old living long had been the point of human evolution,said Olshansky, we probably wouldn't still have"Achilles' heels" such as neurons and muscle fibersthat don't divide and replicate like other cells of ourbodies do.

4 Eventually, when those cells die andaren't replaced, our brains shrink and our who live long enough for these foibles of thehuman body to catch up with them aren't sick whenthey die, their bodies have just worn out, saidOlshansky."There isn't a time bomb that's ticking," he said."But we have a body design that's fixed. We'restructured like we are because natural selectionmade us like we are."For the same reason, he suggests, there may be amechanical limit on how fast a human can run. Wecan train harder, wear better shoes, develop moreaerodynamic techniques to make us faster, hesays. But eventually, we will likely run up againstthe mechanical limitations of the human design(which, after all, evolved to balance speed ofrunning against many other priorities that help ussurvive long enough to reproduce).That sounds right to Steve Horvath, a professor ofgenetics and biostatistics at the University ofCalifornia, Los Angeles' Geffen School of a bid to measure the pace at which individualsand groups of individuals age, Horvath and hiscolleagues have systematically looked at theactivity of the epigenome.

5 That's the set of chemicalsignals that prompts our genes, which remainlargely fixed and stable from birth until death, tochange their function across the lifespan inresponse to new gauging the epigenetic activity of more than13,000 humans across the spectrum of age andethnicity, Horvath has observed that ourepigenomes switch genes on and off in complexbut predictable patterns across our lifespans. If youknow what to look for, you can see beyond the hairdye and good grooming and actually tell how oldsomeone is of us age faster or more slowly than others,says Horvath. (Last week, he published a study inthe journal Aging that identified an epigeneticpattern shared by 5 percent of the population thatages at a distinctly faster-than-usual rate). Butthese epigenetic regularities confirm that we allage, he says. Query the epigenome and someoneclosing in on his 90th birthday will always lookradically different from a it's not hard to imagine, Horvath says, that afterwe have aged beyond the point of reproduction,nature has done little to assure the means to go onliving indefinitely.

6 "I agree with the thought expressed by the authorsthat a natural limit of human lifespan (around 125years) could be an inadvertent byproduct of a fixedgenetic program for development and growth,"Horvath good news, Olshansky says, is that "there'slots we can do" - not only to add years to our livesbut to add life to our a species, of course, we can readily improve lifeexpectancy - just a statistical average, to be sure,but one that could mean longer lives for many. Wecan prevent disease and improve public health bymaking clean water, healthier habits and goodmaternity care more universal. We can continue totreat diseases of aging with better and more widelyused therapies for cancer, heart problems,neurodegenerative disease and all the disorders(such as Type 2 diabetes and hypertension) thatprecede to ensure that more individuals live healthier forlonger - and that more of us challenge the seeminglimits of human longevity - Olshansky says we'llhave to do more than treat diseases of aging withstents, procedures, pills and the occasional , he says, scientists should be focusingmore on slowing the speed at which we age, bygleaning insights from research such as Horvath' the pace of aging and someone blowing out125 candles on her birthday cake might just be 96 2 / 3 on the inside and keep on living.

7 "Can we bust through" a natural limit to human life?asks Horvath. "Yes," he says, "with a new paradigmthat focuses on aging and not diseases." 2016 Los Angeles TimesDistributed by Tribune Content Agency, citation: when , and why , must we die? (2016, October 7) retrieved 9 October 2019 from document is subject to copyright. Apart from any fair dealing for the purpose of private study or research, nopart may be reproduced without the written permission. The content is provided for information purposes by TCPDF ( ) 3 / 3