6 ms·

this makes me think that telomeres are not the main cause of aging-related death. My mental model is: if you run out of telomere before you get old, you start t

this makes me think that telomeres are not the main cause of aging-related death. My mental model is: if you run out of telomere before you get old, you start to get disease - and that’s maladaptive. So there’s evolutionary pressure to slow down your shortening rate, up to a point. Once it becomes unlikely that you’ll outlive your telomeres, there’s no more pressure. So your telomere length + rate becomes a measurement of your species lifespan.

LegitShady 7y ago
tl;dr might not be the bottleneck, so the telomere length and shortening rate is measuring something else that is.
- waterhouse 7y ago
  If you do end up with telomeres that shorten very slowly, could there also be pressure to shorten them more quickly, so it really is just a measurement? Hypothesis: telomerase, which fights the shortening, also promotes cancer. I think I've even seen that before. "Some experiments have raised questions on whether telomerase can be used as an anti-aging therapy, namely, the fact that mice with elevated levels of telomerase have higher cancer incidence and hence do not live longer. Telomerase also favors tumorogenesis, which leads to questions about its potential as an anti-aging therapy.[36] On the other hand, one study showed that activating telomerase in cancer-resistant mice by overexpressing its catalytic subunit extended lifespan.[37] A study that focused on Ashkenazi Jews found that long-lived subjects inherited a hyperactive version of telomerase.[38] " https://en.wikipedia.org/wiki/Telomerase https://en.wikipedia.org/wiki/Telomerase Ambiguous.
jayd16 7y ago
This doesn't really make sense does it? There's only really evolutionary pressure up to the end of your child rearing years, no?
- afthonos 7y ago
  Should be context dependent. New parents benefit a lot from their own elder family members giving them advice on the basics; in an environment with less information (i.e. no internet), the advantage vs. people with no parents or family to help would have been substantial. So unless we expand the definition of “child-rearing years”, I think it could go either way.
  - RomanBob 7y ago
    for any amount of food, it's better to have an adult rather than an elder, for any particular gene. So a truly optimal age system would have no old age at all, you will just die off after your children are self-sustaining.
- anticensor 7y ago
  Humans are double-viviparous species, meaning average grandparent lives past its grandchild's puberty. Humans are also atricial. These traits are shared by elephants, whales and dolphins too. However, humans are the only animal species those are triple-viviparous in occasions, meaning great-grandparent lives past its great-grandchild's puberty.
  - collyw 7y ago
    Human's average lifespans have been a lot shorter throughout history.
    - tomp 7y ago
      Average isn't that relevant. It's driven down by early childhood deaths & childbirth deaths (but after a point - menopause - childbirth deaths end).
      - collyw 7y ago
        Infectious disease killed many before old age. Antibiotics are a pretty recent invention.
mysterypie 7y ago
> this makes me think that telomeres are not the main cause of aging-related death That's an interesting argument, but couldn't you use the same reasoning to argue that telomeres are the main cause of aging-related death? The mental model I'm thinking is: As you run out of telomeres, you get diseases and you can't reproduce - and that’s maladaptive. So there’s evolutionary pressure to slow down the shortening rate, up to the point where you have children (plus grandchildren in the case of humans). When you're living long enough to have one or two generations of offspring, there’s no more pressure to correct the telomere problem. Wouldn't your argument and mine be equally consistent with the featured article (that shortening rate predicts life span)?
- pawelmurias 7y ago
  If you lived longer still you might father more children.
  - kuprel 7y ago
    There's probably pressure for species to not have longer lifespans. Youthful thinking and fresh perspectives are important. Wise old perspectives can get deeply ingrained and can't be changed easily. The free market for example experiences similar phenomenon where a new startup will outcompete a big old corporation. An industry that moves quicker (tech) evolves faster than one that doesn't (healthcare).
    - tensor 7y ago
      The evidence doesn't support what you imply: that older people can't learn or come up with novel ideas. Fresh perspectives are important, but there are more ways than ignorance (e.g. youth) to find them. For example, cross domain work often yields amazing new results; it's a great way to bring in fresh perspectives.
    - jariel 7y ago
      New companies don't beat older one's because they inherently have 'fresh perspective' the older one's are incapable of. 'Old companies' are entrenched and incumbent gears in the system and are effectively mining economic rent. They don't want change because change will disrupt the cash cow. Newer companies have to break into the system and have to do that, at which time they'll want to sink their claws into the system as well. There are plenty of newer ideas at big companies, but systematically they tend to be averse to them in favour of other strategies.

LegitShady 7y ago

tl;dr might not be the bottleneck, so the telomere length and shortening rate is measuring something else that is.

waterhouse 7y ago
If you do end up with telomeres that shorten very slowly, could there also be pressure to shorten them more quickly, so it really is just a measurement? Hypothesis: telomerase, which fights the shortening, also promotes cancer. I think I've even seen that before. "Some experiments have raised questions on whether telomerase can be used as an anti-aging therapy, namely, the fact that mice with elevated levels of telomerase have higher cancer incidence and hence do not live longer. Telomerase also favors tumorogenesis, which leads to questions about its potential as an anti-aging therapy.[36] On the other hand, one study showed that activating telomerase in cancer-resistant mice by overexpressing its catalytic subunit extended lifespan.[37] A study that focused on Ashkenazi Jews found that long-lived subjects inherited a hyperactive version of telomerase.[38] " https://en.wikipedia.org/wiki/Telomerase https://en.wikipedia.org/wiki/Telomerase Ambiguous.

jayd16 7y ago

This doesn't really make sense does it? There's only really evolutionary pressure up to the end of your child rearing years, no?

afthonos 7y ago
Should be context dependent. New parents benefit a lot from their own elder family members giving them advice on the basics; in an environment with less information (i.e. no internet), the advantage vs. people with no parents or family to help would have been substantial. So unless we expand the definition of “child-rearing years”, I think it could go either way.
- RomanBob 7y ago
  for any amount of food, it's better to have an adult rather than an elder, for any particular gene. So a truly optimal age system would have no old age at all, you will just die off after your children are self-sustaining.
anticensor 7y ago
Humans are double-viviparous species, meaning average grandparent lives past its grandchild's puberty. Humans are also atricial. These traits are shared by elephants, whales and dolphins too. However, humans are the only animal species those are triple-viviparous in occasions, meaning great-grandparent lives past its great-grandchild's puberty.
- collyw 7y ago
  Human's average lifespans have been a lot shorter throughout history.
  - tomp 7y ago
    Average isn't that relevant. It's driven down by early childhood deaths & childbirth deaths (but after a point - menopause - childbirth deaths end).
    - collyw 7y ago
      Infectious disease killed many before old age. Antibiotics are a pretty recent invention.

mysterypie 7y ago

> this makes me think that telomeres are not the main cause of aging-related death That's an interesting argument, but couldn't you use the same reasoning to argue that telomeres are the main cause of aging-related death? The mental model I'm thinking is: As you run out of telomeres, you get diseases and you can't reproduce - and that’s maladaptive. So there’s evolutionary pressure to slow down the shortening rate, up to the point where you have children (plus grandchildren in the case of humans). When you're living long enough to have one or two generations of offspring, there’s no more pressure to correct the telomere problem. Wouldn't your argument and mine be equally consistent with the featured article (that shortening rate predicts life span)?

pawelmurias 7y ago
If you lived longer still you might father more children.
- kuprel 7y ago
  There's probably pressure for species to not have longer lifespans. Youthful thinking and fresh perspectives are important. Wise old perspectives can get deeply ingrained and can't be changed easily. The free market for example experiences similar phenomenon where a new startup will outcompete a big old corporation. An industry that moves quicker (tech) evolves faster than one that doesn't (healthcare).
  - tensor 7y ago
    The evidence doesn't support what you imply: that older people can't learn or come up with novel ideas. Fresh perspectives are important, but there are more ways than ignorance (e.g. youth) to find them. For example, cross domain work often yields amazing new results; it's a great way to bring in fresh perspectives.
  - jariel 7y ago
    New companies don't beat older one's because they inherently have 'fresh perspective' the older one's are incapable of. 'Old companies' are entrenched and incumbent gears in the system and are effectively mining economic rent. They don't want change because change will disrupt the cash cow. Newer companies have to break into the system and have to do that, at which time they'll want to sink their claws into the system as well. There are plenty of newer ideas at big companies, but systematically they tend to be averse to them in favour of other strategies.