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It's a different topic, but related. I was marveling at the diversity of life on Earth, which led me wonder: to what extent does sustained life on Earth depend

It's a different topic, but related. I was marveling at the diversity of life on Earth, which led me wonder: to what extent does sustained life on Earth depend on that diversity? I.e., what would be required or different for a planet to host and sustain a single species of life? Given the nature of evolution, and that one subscribes to it, life on Earth started with a single organism that replicated. From that point until a replication modified the organism into a different species, there would have been one species. But was it necessary to have multiple species in order to sustain life?

heckerhut 9y ago
Yes. Evolution is actually its own evidence. Biological evolution evolved out of necessity. Without constantly changing evolutionary pressures exerted by an organism's external environment there would be no need for evolution and it therefore wouldn't have evolved.
- idlewords 9y ago
  That's the opposite of an evolutionary argument. Evolution is not teleological, it doesn't arise to meet a need. It's a kind of feedback loop in low-entropy systems that given enough time can produce interesting phenomena, including this message board.
oblib 9y ago
"life on Earth started with a single organism that replicated." I would tend to ponder that life in it's simplest form is not singular and never has been and this is the cause of evolution.
- dredmorbius 9y ago
  Available evidence suggests that life on Earth has a common ancestor. This doesn't mean it was the only origin of life on Earth, but it is the only surviving line. It also took a few days for complexity to arise. About a trillion of them.
  - oblib 9y ago
    "Available evidence" : that's because we still don't know how to look for it, or what to look for, and the reasons for that are complexity and time.
    - dredmorbius 9y ago
      Wrong. "Available evidence", because there are no extant lifeforms which diverge from the known set of amino acids, no prokaryotic life which doesn't have (or at least didn't once have) mitochondria, utilisation of the Krebs Cycle, and numerous other elements. Again, other variants might have emerged. But they haven't survived, suggesting the extant line out-competed (or possibly out-lucked) any challengers

heckerhut 9y ago

Yes. Evolution is actually its own evidence. Biological evolution evolved out of necessity. Without constantly changing evolutionary pressures exerted by an organism's external environment there would be no need for evolution and it therefore wouldn't have evolved.

idlewords 9y ago
That's the opposite of an evolutionary argument. Evolution is not teleological, it doesn't arise to meet a need. It's a kind of feedback loop in low-entropy systems that given enough time can produce interesting phenomena, including this message board.

oblib 9y ago

"life on Earth started with a single organism that replicated." I would tend to ponder that life in it's simplest form is not singular and never has been and this is the cause of evolution.

dredmorbius 9y ago
Available evidence suggests that life on Earth has a common ancestor. This doesn't mean it was the only origin of life on Earth, but it is the only surviving line. It also took a few days for complexity to arise. About a trillion of them.
- oblib 9y ago
  "Available evidence" : that's because we still don't know how to look for it, or what to look for, and the reasons for that are complexity and time.
  - dredmorbius 9y ago
    Wrong. "Available evidence", because there are no extant lifeforms which diverge from the known set of amino acids, no prokaryotic life which doesn't have (or at least didn't once have) mitochondria, utilisation of the Krebs Cycle, and numerous other elements. Again, other variants might have emerged. But they haven't survived, suggesting the extant line out-competed (or possibly out-lucked) any challengers