3 ms·

The Evolution of Senescence (2022)

47 points by yamrzou 3y ago

m463 3y ago
It seems to me senescent cells build up because we always have enough food. I wonder if we (and other species) would metabolize senescent cells during the famine part of feast or famine. or mindfully though intermittent fasting.
- fnordpiglet 3y ago
  Essentially the answer is “yes,” particularly when coupled with exercise. A quick Kagi can find a lot of research and background. However most research (if not all) is mouse based, which have dramatically different metabolisms, evolutionary environmental pressures, and life spans so there’s a lot of question whether the results actually transfer to a long lived mammal.
- dsign 3y ago
  > It seems to me senescent cells build up because we always have enough food Sorry, I don't see the "logic" on this. I see the logic on the article though, which boils down to this: our bodies' only goal is species' permanence, and every investment in maintenance or otherwise must contribute to that. If I were designing my own body, I would put any excess of energy into cellular maintenance. On the other hand, nature would want me to accumulate fat for when the winter comes and my hole next to the tree stump gets cold. Here is something that I keep thinking: you can't compare a living organism to, say, an airplane, because an airplane has fixed structural parts which are impossible to replace, and those parts accumulate tear and wear. A living organism on the other hand can gradually replace each of its parts (molecules, cells, organs), provided it has/runs the program to do so. So, senescence and mortality are not fundamental laws of physics, but simply ways in which evolution has accommodated things.
  - catlifeonmars 3y ago
    > Here is something that I keep thinking: you can't compare a living organism to, say, an airplane, because an airplane has fixed structural parts which are impossible to replace, and those parts accumulate tear and wear. Not an airplane, but Alvin (the deep sea research vessel) has had all of its parts replaced over time. It’s a modern day ship of Theseus.
    - dsign 3y ago
      I didn't know that. Thanks!
melagonster 3y ago
this is a very beautiful article. it wrote for newhands but writing in review format! I recommend new biology students read this.
JPLeRouzic 3y ago
> "Stearns et al (2000) imposed a high mortality regime on one group of fruit flies, and observed that their experimental group lived a shorter life and a reduced age of sexual maturity." Humanity is currently experiencing a reduced age of sexual maturity: https://en.wikipedia.org/wiki/Menarche https://en.wikipedia.org/wiki/Menarche "In the last two centuries, the average age at first period has been falling continuously in France. In 1750 it is estimated to have been close to 16; by 1850 it was down to 15, and by 1950 it had fallen to 13. In 1994, it stood at 12.6 years of age." https://www.ined.fr/en/everything_about_population/demographic-facts-sheets/focus-on/age_menstruation/ https://www.ined.fr/en/everything_about_population/demograph...
- circlefavshape 3y ago
  I hear this all the time, but the wikipedia article seems to say the evidence is pretty weak. Juliet was 13 when herself and Romeo got together
  - bitwize 3y ago
    In India it used to be expected to be married and starting to have kids by age 12 or so. In the novel Nectar in a Sieve, main character Rukmani is worried that her daughter will be an old maid forever when she remains unmarried at the ripe old age of... 14.
  - klbinz 3y ago
    When I looked, the evidence I found was quite strong. Younger age of maturity seems to be driven by nutritional improvements of the Industrial Revolution. > Compared to the 19th century, women have become younger and taller at age of maturity (Worthman 1999). This secular trend has been most intense within groups of low socioeconomic status (SES) (e.g., Abioye-Kuteyi et al 1997). This class effect only pertains to countries where low SES groups do not suffer from systematic malnutrition and disease (it is absent in e.g., Denmark Helm & Lidegaard 1989). https://kevinbinz.com/2022/08/18/the-pace-of-life/ https://kevinbinz.com/2022/08/18/the-pace-of-life/
    - 3y ago

47 points by yamrzou 3y ago

m463 3y ago

It seems to me senescent cells build up because we always have enough food. I wonder if we (and other species) would metabolize senescent cells during the famine part of feast or famine. or mindfully though intermittent fasting.

fnordpiglet 3y ago
Essentially the answer is “yes,” particularly when coupled with exercise. A quick Kagi can find a lot of research and background. However most research (if not all) is mouse based, which have dramatically different metabolisms, evolutionary environmental pressures, and life spans so there’s a lot of question whether the results actually transfer to a long lived mammal.
dsign 3y ago
> It seems to me senescent cells build up because we always have enough food Sorry, I don't see the "logic" on this. I see the logic on the article though, which boils down to this: our bodies' only goal is species' permanence, and every investment in maintenance or otherwise must contribute to that. If I were designing my own body, I would put any excess of energy into cellular maintenance. On the other hand, nature would want me to accumulate fat for when the winter comes and my hole next to the tree stump gets cold. Here is something that I keep thinking: you can't compare a living organism to, say, an airplane, because an airplane has fixed structural parts which are impossible to replace, and those parts accumulate tear and wear. A living organism on the other hand can gradually replace each of its parts (molecules, cells, organs), provided it has/runs the program to do so. So, senescence and mortality are not fundamental laws of physics, but simply ways in which evolution has accommodated things.
- catlifeonmars 3y ago
  > Here is something that I keep thinking: you can't compare a living organism to, say, an airplane, because an airplane has fixed structural parts which are impossible to replace, and those parts accumulate tear and wear. Not an airplane, but Alvin (the deep sea research vessel) has had all of its parts replaced over time. It’s a modern day ship of Theseus.
  - dsign 3y ago
    I didn't know that. Thanks!

melagonster 3y ago

this is a very beautiful article. it wrote for newhands but writing in review format! I recommend new biology students read this.

JPLeRouzic 3y ago

> "Stearns et al (2000) imposed a high mortality regime on one group of fruit flies, and observed that their experimental group lived a shorter life and a reduced age of sexual maturity." Humanity is currently experiencing a reduced age of sexual maturity: https://en.wikipedia.org/wiki/Menarche https://en.wikipedia.org/wiki/Menarche "In the last two centuries, the average age at first period has been falling continuously in France. In 1750 it is estimated to have been close to 16; by 1850 it was down to 15, and by 1950 it had fallen to 13. In 1994, it stood at 12.6 years of age." https://www.ined.fr/en/everything_about_population/demographic-facts-sheets/focus-on/age_menstruation/ https://www.ined.fr/en/everything_about_population/demograph...

circlefavshape 3y ago
I hear this all the time, but the wikipedia article seems to say the evidence is pretty weak. Juliet was 13 when herself and Romeo got together
- bitwize 3y ago
  In India it used to be expected to be married and starting to have kids by age 12 or so. In the novel Nectar in a Sieve, main character Rukmani is worried that her daughter will be an old maid forever when she remains unmarried at the ripe old age of... 14.
- klbinz 3y ago
  When I looked, the evidence I found was quite strong. Younger age of maturity seems to be driven by nutritional improvements of the Industrial Revolution. > Compared to the 19th century, women have become younger and taller at age of maturity (Worthman 1999). This secular trend has been most intense within groups of low socioeconomic status (SES) (e.g., Abioye-Kuteyi et al 1997). This class effect only pertains to countries where low SES groups do not suffer from systematic malnutrition and disease (it is absent in e.g., Denmark Helm & Lidegaard 1989). https://kevinbinz.com/2022/08/18/the-pace-of-life/ https://kevinbinz.com/2022/08/18/the-pace-of-life/
  - 3y ago