4 ms·

It's remarkable that the components of the nerve system are very ancient and were all in place in the ur-bilaterian.

mentos 8y ago
It’s crazy how life just kept building and building on itself. I feel like there were so many opportunities for life to hit a ceiling and never evolve past X stage but yet somehow we broke out.
- ur-whale 8y ago
  Given enough starting points, any local optimizer will eventually crawl out of local extrema.
- mcguire 8y ago
  If I recall correctly, the division between prokaryotes and eukaryotes took billions of years. Multicellular life was another big step. Everything after that is easy. I remind myself that every morning. :-)
  - Emma_Goldman 8y ago
    I've heard this said many times and believed it, but read to day that the leap from single-cell to multi-cellular organisms happened a dozen or so times independent of each other. That makes it an order of magnitude less improbable, if true.
    - gus_massa 8y ago
      Yep, from https://en.wikipedia.org/wiki/Multicellular_organism#Occurrence https://en.wikipedia.org/wiki/Multicellular_organism#Occurre... > [...] However, complex multicellular organisms evolved only in six eukaryotic groups: animals, fungi, brown algae, red algae, green algae, and land plants. It evolved repeatedly for Chloroplastida (green algae and land plants), once or twice for animals, once for brown algae, three times in the fungi (chytrids, ascomycetes and basidiomycetes) and perhaps several times for slime molds and red algae.
    - Brockenstein 8y ago
      Lots of things evolved multiple times independently. And while we make a big deal about multi-cellular life, there's still nothing so special about it that that is the one thing that could only have happened once...
- nindalf 8y ago
  The environment kept changing too. Even if an organism evolved to a local maxima where it was the master of it's domain, the climate or geography could change. Or a giant meteor could fall on it's head. At that point, the maximas change.
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.
quotemstr 8y ago
I've always been a bit disappointed that evolution basically fixed all today's high level body plans about 500 million years ago. Lots of evolution since then has involved turning the crank on incremental and higher-level improvements (most famously, intelligence), but I don't see a lot of innovation in basic biomechanics. It reminds me of how everyone is willing to experiment with new neural network training algorithms in the software world, but you need tremendous resistance trying to change parts of POSIX to suck less. It's as if in both nature and computing, there's some conservation in the amount of experimentation we're willing to tolerate.

It’s crazy how life just kept building and building on itself. I feel like there were so many opportunities for life to hit a ceiling and never evolve past X stage but yet somehow we broke out.

ur-whale 8y ago
Given enough starting points, any local optimizer will eventually crawl out of local extrema.
mcguire 8y ago
If I recall correctly, the division between prokaryotes and eukaryotes took billions of years. Multicellular life was another big step. Everything after that is easy. I remind myself that every morning. :-)
- Emma_Goldman 8y ago
  I've heard this said many times and believed it, but read to day that the leap from single-cell to multi-cellular organisms happened a dozen or so times independent of each other. That makes it an order of magnitude less improbable, if true.
  - gus_massa 8y ago
    Yep, from https://en.wikipedia.org/wiki/Multicellular_organism#Occurrence https://en.wikipedia.org/wiki/Multicellular_organism#Occurre... > [...] However, complex multicellular organisms evolved only in six eukaryotic groups: animals, fungi, brown algae, red algae, green algae, and land plants. It evolved repeatedly for Chloroplastida (green algae and land plants), once or twice for animals, once for brown algae, three times in the fungi (chytrids, ascomycetes and basidiomycetes) and perhaps several times for slime molds and red algae.
  - Brockenstein 8y ago
    Lots of things evolved multiple times independently. And while we make a big deal about multi-cellular life, there's still nothing so special about it that that is the one thing that could only have happened once...
nindalf 8y ago
The environment kept changing too. Even if an organism evolved to a local maxima where it was the master of it's domain, the climate or geography could change. Or a giant meteor could fall on it's head. At that point, the maximas change.

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.

quotemstr 8y ago

I've always been a bit disappointed that evolution basically fixed all today's high level body plans about 500 million years ago. Lots of evolution since then has involved turning the crank on incremental and higher-level improvements (most famously, intelligence), but I don't see a lot of innovation in basic biomechanics. It reminds me of how everyone is willing to experiment with new neural network training algorithms in the software world, but you need tremendous resistance trying to change parts of POSIX to suck less. It's as if in both nature and computing, there's some conservation in the amount of experimentation we're willing to tolerate.