3 ms·

So you're saying that aging is basically growth control?

by pier25 4y ago

ezconnect 4y ago
Growing means you're making new cell, aging is when you're cell seems tired and stop regenerating or being eaten by other cells.
- pier25 4y ago
  Aren't cells replaced periodically?
  - space_fountain 4y ago
    Yes, but in a very controlled way, typically with a fixed number of total devisions. Understanding aging is a slow process, but as far as I know current thought is that it has a lot to do with that replacement slowing down for a variety of reasons. This slow down seems like it may somewhat be a tradeoff with cancer though. Cells that divide too robustly end up cancer, cells that sort of shutdown instead are known as senescent and seem to contribute to aging
escapecharacter 4y ago
if you were optimizing for success for a whole species, do you see how going for fast iterations and throwing out old code could appear as a strategy?
- hwillis 4y ago
  It's the opposite. You don't have children when you die, and evolution occurs overwhelmingly due to genetic diversity rather than iteration. That is, mutations are not nearly as important as the number of parents with diverse code to recombine with. Excluding older individuals causes the gene pool to become more consistent, because mutations are easier to lose. If iteration was important, sexual maturity would occur drastically younger in birds and mammals, and you'd have tons of offspring to maximize iteration. Reptiles are the ones that have tons of children.
  - hackinthebochs 4y ago
    In a competitive environment, success is a function of fitness over your competitors. The fitness of a population is a function of the speed of fixation of advantageous alleles, which itself is a function of the number of generations. Thus in competitive environments, selective pressure towards generational turnover is increased, which is accomplished by aging. The issue of genetic diversity is satisfied by the close relationship of parent-offspring diversity. There's no reason to keep prior generations around just for the sake of genetic diversity. >If iteration was important, sexual maturity would occur drastically younger in birds and mammals, and you'd have tons of offspring to maximize iteration There are always antagonist selective pressures, e.g. selective pressures towards longer childhoods and fewer offspring when parental investment requirements grow.
    - shadowofneptune 4y ago
      > There's no reason to keep prior generations around just for the sake of genetic diversity. This assumes there is some sort of reasoning going on in natural selection. What would lead to mutations that promote aging being selection per se, when the effects of aging are only experienced after reproductive age? That's not ruling out that mutations that cause aging aren't selected for, but they should give some short-term advantage.
      - hackinthebochs 4y ago
        The short-term advantage to the group is in reduced energy requirements from slowing metabolism. Also the prior generation is made less attractive to the next generation thus promoting the faster turnover of generations.
- shadowofneptune 4y ago
  The article states: “It sounds dramatic to say that they don’t age at all, but basically their likelihood of dying does not change with age once they’re past reproduction,” says Reinke." In humans, kids are born well below the age when we see the worst effects of aging. The old do not play much of a role in natural selection. It seems likely that aging or lack of it is more of an accident, then.

So you're saying that aging is basically growth control?

by pier25 4y ago

So you're saying that aging is basically growth control?

Growing means you're making new cell, aging is when you're cell seems tired and stop regenerating or being eaten by other cells.

pier25 4y ago
Aren't cells replaced periodically?
- space_fountain 4y ago
  Yes, but in a very controlled way, typically with a fixed number of total devisions. Understanding aging is a slow process, but as far as I know current thought is that it has a lot to do with that replacement slowing down for a variety of reasons. This slow down seems like it may somewhat be a tradeoff with cancer though. Cells that divide too robustly end up cancer, cells that sort of shutdown instead are known as senescent and seem to contribute to aging

escapecharacter 4y ago

if you were optimizing for success for a whole species, do you see how going for fast iterations and throwing out old code could appear as a strategy?

hwillis 4y ago
It's the opposite. You don't have children when you die, and evolution occurs overwhelmingly due to genetic diversity rather than iteration. That is, mutations are not nearly as important as the number of parents with diverse code to recombine with. Excluding older individuals causes the gene pool to become more consistent, because mutations are easier to lose. If iteration was important, sexual maturity would occur drastically younger in birds and mammals, and you'd have tons of offspring to maximize iteration. Reptiles are the ones that have tons of children.
- hackinthebochs 4y ago
  In a competitive environment, success is a function of fitness over your competitors. The fitness of a population is a function of the speed of fixation of advantageous alleles, which itself is a function of the number of generations. Thus in competitive environments, selective pressure towards generational turnover is increased, which is accomplished by aging. The issue of genetic diversity is satisfied by the close relationship of parent-offspring diversity. There's no reason to keep prior generations around just for the sake of genetic diversity. >If iteration was important, sexual maturity would occur drastically younger in birds and mammals, and you'd have tons of offspring to maximize iteration There are always antagonist selective pressures, e.g. selective pressures towards longer childhoods and fewer offspring when parental investment requirements grow.
  - shadowofneptune 4y ago
    > There's no reason to keep prior generations around just for the sake of genetic diversity. This assumes there is some sort of reasoning going on in natural selection. What would lead to mutations that promote aging being selection per se, when the effects of aging are only experienced after reproductive age? That's not ruling out that mutations that cause aging aren't selected for, but they should give some short-term advantage.
    - hackinthebochs 4y ago
      The short-term advantage to the group is in reduced energy requirements from slowing metabolism. Also the prior generation is made less attractive to the next generation thus promoting the faster turnover of generations.
shadowofneptune 4y ago
The article states: “It sounds dramatic to say that they don’t age at all, but basically their likelihood of dying does not change with age once they’re past reproduction,” says Reinke." In humans, kids are born well below the age when we see the worst effects of aging. The old do not play much of a role in natural selection. It seems likely that aging or lack of it is more of an accident, then.