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I think this is a step in the right direction, but it still has the central issue that looking for oxygen rich planets (or any atmosphere with a disproportionat

I think this is a step in the right direction, but it still has the central issue that looking for oxygen rich planets (or any atmosphere with a disproportionately high quantity of some suitable agent for reduction (respiration). We didn't even get around to the whole respiration thing on this planet for quite a long time, and there's no requisite that ATP/ respiration is the direction life is going to take, and equally, in the event of some kind of reductive respiration, there's not a prerequisite that oxygen be that agent, although its a pretty good candidate.

vanderZwan 9y ago
> there's no requisite that ATP/ respiration is the direction life is going to take Based on the article I linked in my other comment I would say that on oxygen-rich planets, respiration is likely to happen simply because life needs to find a way to deal with it's toxicity, or perish. Although that presupposes that photosynthesis is inevitable, which also doesn't have to be true. I kind of wonder how much we truly know about the strength of lock-in effects of evolution - of how much life is "stuck" with old hacks that we can no longer get rid of or that lead to dead ends. I doubt we'd ever evolve avian lungs from where we are now, for example. I know there are examples like that all over the place, but just how strong is the effect?
- plushpuffin 9y ago
  As one example on a physical rather than a chemical level, I read that marsupials are stuck for this reason. They need claws to climb into their mother's pouch after birth, so there are certain ecological niches closed off to them. You'll never see a hoofed marsupial, for example.
  - plushpuffin 9y ago
    Found a source: https://synapsida.blogspot.com/2011/11/why-marsupials-cant-fly.html https://synapsida.blogspot.com/2011/11/why-marsupials-cant-f...
    - vanderZwan 9y ago
      I've heard that the cheetah is considered an evolutionary dead end as well, being so hyper-specialised for speed that they are unlikely to be able to keep up the arms race with their prey, nor able to evolve back out of this.
- trhway 9y ago
  >Although that presupposes that photosynthesis is inevitable, which also doesn't have to be true. there are options. For example radiosynthesis like is done by these fungi discovered in Chernobyl https://en.wikipedia.org/wiki/Radiotrophic_fungus https://en.wikipedia.org/wiki/Radiotrophic_fungus
- JeanSebTr 9y ago
  It would be Life's technical debt :D
  - vanderZwan 9y ago
    Hah, guess it kind of is! Maybe genetic engineering will eventually lead to a huge increase in biodiversity...

vanderZwan 9y ago

> there's no requisite that ATP/ respiration is the direction life is going to take Based on the article I linked in my other comment I would say that on oxygen-rich planets, respiration is likely to happen simply because life needs to find a way to deal with it's toxicity, or perish. Although that presupposes that photosynthesis is inevitable, which also doesn't have to be true. I kind of wonder how much we truly know about the strength of lock-in effects of evolution - of how much life is "stuck" with old hacks that we can no longer get rid of or that lead to dead ends. I doubt we'd ever evolve avian lungs from where we are now, for example. I know there are examples like that all over the place, but just how strong is the effect?

plushpuffin 9y ago
As one example on a physical rather than a chemical level, I read that marsupials are stuck for this reason. They need claws to climb into their mother's pouch after birth, so there are certain ecological niches closed off to them. You'll never see a hoofed marsupial, for example.
- plushpuffin 9y ago
  Found a source: https://synapsida.blogspot.com/2011/11/why-marsupials-cant-fly.html https://synapsida.blogspot.com/2011/11/why-marsupials-cant-f...
  - vanderZwan 9y ago
    I've heard that the cheetah is considered an evolutionary dead end as well, being so hyper-specialised for speed that they are unlikely to be able to keep up the arms race with their prey, nor able to evolve back out of this.
trhway 9y ago
>Although that presupposes that photosynthesis is inevitable, which also doesn't have to be true. there are options. For example radiosynthesis like is done by these fungi discovered in Chernobyl https://en.wikipedia.org/wiki/Radiotrophic_fungus https://en.wikipedia.org/wiki/Radiotrophic_fungus
JeanSebTr 9y ago
It would be Life's technical debt :D
- vanderZwan 9y ago
  Hah, guess it kind of is! Maybe genetic engineering will eventually lead to a huge increase in biodiversity...