3 ms·

The issue is rate of environment change. If your individuals have 100-year lifetimes and changes occur at 1-year rate, then clearly there's a problem. Even if t

The issue is rate of environment change. If your individuals have 100-year lifetimes and changes occur at 1-year rate, then clearly there's a problem. Even if those 100-year individuals reproduce throughout their lives, the older individuals won't bear modifications. So if the environment can change quickly, it's plausible there's a mechanism to secure existential threats to the species by maintaining a short reproductive cycle at the expense of extra overhead to recreate individuals.

Symmetry 11y ago
Generally the metric is how fast the environment changes versus how fast new generations are produced. If a population can breed rapidly then it can adapt to fast environmental changes no matter how long the members live. If it breeds slowly it cannot adapt to rapid environmental changes no matter how long it's members live.
- darkmighty 11y ago
  I was being careful because I think it's not so simple. Some changes are not deleterious (don't cause death), but still confer subtle cumulative benefits. If individuals live arbitrarily long, you might be accumulating old material that slows down evolution. In that example, if your individuals live for 100 years and you have a 1-year reproduction cycle, each year only 1% of your population is new.
  - Symmetry 11y ago
    That would only be true if all individuals were living to the full 100 years their biology allowed. That the sort of environment that bacteria in a growth medium have but not something you would see in a steady state. And also remember that every organism would reproduce each year so you would have %50 of you population new each year unless the oldest organisms can somehow prevent the youngest ones from reproducing. I would agree that that last would be something that evolution would tend to prevent.
    - darkmighty 11y ago
      I see, I agree on that (though I think I would need to do some concrete modelling to clear it in my head). It's just so intuitive that short lifespan creatures evolve quicker... take Blue Whales versus Viruses or Plankton. I might be thinking necessarily they're correlated variables in nature, not that there's a direct mechanism cutting off lifespans. Consider the possibility that creatures with longer avg. lifespans must have longer development time until reproduction. This will affect the average lifetime of reproducing individuals -- so it's an example of longer lifetimes implying slower evolution. In other words, I'm thinking it might be a sort of necessary correlation.

Symmetry 11y ago

Generally the metric is how fast the environment changes versus how fast new generations are produced. If a population can breed rapidly then it can adapt to fast environmental changes no matter how long the members live. If it breeds slowly it cannot adapt to rapid environmental changes no matter how long it's members live.

darkmighty 11y ago
I was being careful because I think it's not so simple. Some changes are not deleterious (don't cause death), but still confer subtle cumulative benefits. If individuals live arbitrarily long, you might be accumulating old material that slows down evolution. In that example, if your individuals live for 100 years and you have a 1-year reproduction cycle, each year only 1% of your population is new.
- Symmetry 11y ago
  That would only be true if all individuals were living to the full 100 years their biology allowed. That the sort of environment that bacteria in a growth medium have but not something you would see in a steady state. And also remember that every organism would reproduce each year so you would have %50 of you population new each year unless the oldest organisms can somehow prevent the youngest ones from reproducing. I would agree that that last would be something that evolution would tend to prevent.
  - darkmighty 11y ago
    I see, I agree on that (though I think I would need to do some concrete modelling to clear it in my head). It's just so intuitive that short lifespan creatures evolve quicker... take Blue Whales versus Viruses or Plankton. I might be thinking necessarily they're correlated variables in nature, not that there's a direct mechanism cutting off lifespans. Consider the possibility that creatures with longer avg. lifespans must have longer development time until reproduction. This will affect the average lifetime of reproducing individuals -- so it's an example of longer lifetimes implying slower evolution. In other words, I'm thinking it might be a sort of necessary correlation.