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We read that ageing is related to cell death when we run out of telomeres at the end of our DNA molecules. Humans live roughly for 70 years - the traditional three-score years and ten. This compares with the great apes, such as chimps and gorillas, which live for about 40 years. So we would expect the great apes to have fewer telomeres than humans. In fact the reverse is the case. Humans have telomeres of about 10 kilobases in length whereas the equivalent length in chimps and other great apes is about 23 kilobases. So what is going on? Why do we live longer?

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    $\begingroup$ Great question. However, a few references that contain the numbers would help people answer. +1 $\endgroup$ – AliceD Nov 4 '15 at 3:29
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    $\begingroup$ I think the problem is that you mix up the ageing of a cell with the ageing (or life span) of an organism. Of course the maximal lifespan in a perfect environment could be based on telomere length, but there are other factors shortening this life span as health care, general safety, behaviour,... $\endgroup$ – skymningen Nov 4 '15 at 10:50
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    $\begingroup$ Just remember the life expectancy of Mice is about 3 years, but they have really long telomeres. learn.genetics.utah.edu/content/chromosomes/telomeres I think a lot of the claims on here are absurd, but it gives a general overview. $\endgroup$ – AMR Nov 5 '15 at 3:55
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    $\begingroup$ You are incorrect about your figures. Chimpanzees live up to 60 years of age in captivity. The blog you are quoting is wrong. This is detail from the University of Wisconsin's National Primate Research Center (pin.primate.wisc.edu/factsheets/entry/chimpanzee). $\endgroup$ – AMR Nov 22 '15 at 7:23
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    $\begingroup$ Besides being wrong about telomeres, you are also forgetting the fact that through the 19th century, where we saw public sanitation for the first time and the advent of modern medicine, human life expectancy was between 35-40 years. Prior to the Renaissance and Industrial Revolutions, it was more like 30. So we had similar life expectancies to our cousins up until the point where we figured out the Germ Theory of Disease. $\endgroup$ – AMR Nov 22 '15 at 7:30
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The answer should be obvious: Telomeres do not determine an organism's longevity.

There's only a vague correlation between telomere length and a species' lifespan. See Comparative biology of mammalian telomeres: hypotheses on ancestral states and the roles of telomeres in longevity determination for a starting point. Telomeres are a part of the longevity story, but probably a fairly small part.

The Hayflick limit is generally associated with telomere length. Human telomeres are a little on the long side as species go, but are not extraordinary. Many species of mice, and other rodents, have far longer telomeres than humans, for example, and obviously have much shorter lifespans. There's also such a thing as a "mega-telomere", found in a number of bird species, which can hundreds of times longer than human telomeres.

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  • $\begingroup$ Absolutely. One of the likely culprits is Mitochondria no longer being able to perform their roles properly. Though to improve upon your answer, you should probably paraphrase and reference the paraphrases to the relevant primary literature on aging. $\endgroup$ – AMR Nov 4 '15 at 15:16
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    $\begingroup$ I asked the question because I am an Earth scientist, not a biologist, and I am not familiar with the primary literature. So what is 'trivially obvious' to iayork isn't obvious to me. As I understand it, with each death and replacement of a cell, the telomere shortens. After multiple cell regenerations there are no telomeres left, and the cell dies. The death of millions of cells effectively results in ageing. Maybe I phrased the question badly, but the question still stands: why don't chimps, who have more telomeres, live longer than humans? $\endgroup$ – Gordon Stanger Nov 4 '15 at 22:43
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    $\begingroup$ @rg255 Most recent research on neurodegeneration point to the formation of amyloid plaques due to misfolded proteins being able to nucleate the misfolding in normally folded forms of those proteins. The plaques accumulate and are toxic to the cell. Many of these diseases are associated with aging and they have nothing to do with the length of telomeres. $\endgroup$ – AMR Nov 5 '15 at 3:29
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    $\begingroup$ @iayork I just think being so dismissive of the link between telomeres and ageing is misleading, while telomere length does not determine ageing entirely that does not mean they are unrelated to ageing - nature.com/nrg/journal/v6/n8/full/nrg1656.html and gizmag.com/telomerase-aging-harvard-reverse-process-telomeres/… - besides that discussion, I was only asking for references because that is the normal standards we set on biology SE, which you might not be familiar with as you seem to be fairly new, just trying to be helpful $\endgroup$ – rg255 Nov 5 '15 at 6:12
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    $\begingroup$ Perhaps you could modify your answer to say that between-species the telomere length appears to explain little to none of the variance in ageing, while they appear to some of the variance in ageing within-species, I think this would be a more accurate interpretation and answer to the question. $\endgroup$ – rg255 Nov 5 '15 at 9:51
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There is not one simple cause of aging, like short telomeres, and the fact is that it hasn't even been settled whether aging is caused by evolution failing to evolve good enough repair mechanisms, or whether it evolved with a purpose, it might be that the genes of an organism are better spread if that organism doesn't live too long for example. For more details on the latter debate see this previous issue of Current Aging Science (all the articles are free).

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