3 ms·

It's remarkable how ancient life is in general. Stromatolites have been identified in basically the oldest rocks you can find at ~3.7 Gy and this requires full-

by yborg 8y ago

It's remarkable how ancient life is in general. Stromatolites have been identified in basically the oldest rocks you can find at ~3.7 Gy and this requires full-fledged bacteria. This implies that the very earliest beginnings of self-organizing and propagating biological systems are much older than that, and somehow evolved on an Earth being regularly struck by Chixculub-sized impactors and much more active volcanism. Either the process of evolving life is easier than it seems, or life on Earth has rolled the hard six an awful lot.

andrewflnr 8y ago
This really makes me wonder why we seem to only have one common ancestor. It's starting to look like life happened really early, which means it's really easy, which means it should have happened more than once.
- adrianratnapala 8y ago
  All existing life use a single fairly sophisticated "platform" of basic biochemistry. DNA is by itself a highly evolved thing. Life from an independent origin would probably use a molecule that had a very similar purpose, but the details would be different.
  - andrewflnr 8y ago
    Yes, clearly. My question is why we don't actually see life of independent origin today.
    - adrianratnapala 8y ago
      The answer I heard (and believe) is that new quasi-life would get eaten immediately by some of the far more vigorous and robust life-forms that have already evolved.
    - Brockenstein 8y ago
      This is a good question and there's lots of possible answers. 1. Multiple forms of life did arise at about the same time, but in the end there was one. 2. Multiple forms of life did arise and ended up cross breeding or doing lateral gene transfers or any number novel things. We are the sum result of the earliest forms of life, but it's not like we have everything mapped out there. 3. The potential for new life is all around us, but can't compete with existing life that has millions of years head start. Regardless of where you pick a point after life is already established, a million years later, when the dinosaurs went extinct, 1901, the problem is the same. Something else is already there has been evolving for ages. 4. New life does periodically arise but it's a drop in the ocean and finding that particular drop isn't easy. Assuming it even survives at all for any length of time. 5. We've already seen independent life, but just haven't recognized it as such.

by yborg 8y ago

andrewflnr 8y ago

This really makes me wonder why we seem to only have one common ancestor. It's starting to look like life happened really early, which means it's really easy, which means it should have happened more than once.

adrianratnapala 8y ago
All existing life use a single fairly sophisticated "platform" of basic biochemistry. DNA is by itself a highly evolved thing. Life from an independent origin would probably use a molecule that had a very similar purpose, but the details would be different.
- andrewflnr 8y ago
  Yes, clearly. My question is why we don't actually see life of independent origin today.
  - adrianratnapala 8y ago
    The answer I heard (and believe) is that new quasi-life would get eaten immediately by some of the far more vigorous and robust life-forms that have already evolved.
  - Brockenstein 8y ago
    This is a good question and there's lots of possible answers. 1. Multiple forms of life did arise at about the same time, but in the end there was one. 2. Multiple forms of life did arise and ended up cross breeding or doing lateral gene transfers or any number novel things. We are the sum result of the earliest forms of life, but it's not like we have everything mapped out there. 3. The potential for new life is all around us, but can't compete with existing life that has millions of years head start. Regardless of where you pick a point after life is already established, a million years later, when the dinosaurs went extinct, 1901, the problem is the same. Something else is already there has been evolving for ages. 4. New life does periodically arise but it's a drop in the ocean and finding that particular drop isn't easy. Assuming it even survives at all for any length of time. 5. We've already seen independent life, but just haven't recognized it as such.