4 ms·

Bones not only have to be structurally sound, they also have to be decomposable. Otherwise skeletons would never go away, and it would be too difficult to recl

Bones not only have to be structurally sound, they also have to be decomposable. Otherwise skeletons would never go away, and it would be too difficult to reclaim the raw materials from them. I also have the opinion that bones enable healthier predator/prey relationships because they're just weak enough to get pulverized by a larger physical force (i.e. from a predator). I realize teeth could be steel as well, but in that case muscle would no longer be enough to completely crush a skeleton. Nature really seems to value materials that are just strong enough to get the job done, but just weak enough to get reclaimed easily.

BurritoAlPastor 9y ago
Why do bones need to decompose? What possible evolutionary pressures could be exerted for traits that aren't expressed until after death? (See also the carboniferous period, before the evolution of wood-decomposing bacteria. 60 million years with no decomposition!)
- jdonaldson 9y ago
  Don't confuse trait selection for evolutionary pressures. If previous generation exhaust or over-sequester resources it dooms the species that relies on them. The carboniferous period sequestered a huge amount of carbon. That's a process spread across an enormous time frame. But, that was primarily atmospheric carbon, which can be circulated much better than terrestrial minerals. Since it was atmospheric, you wouldn't have localized shortages (air currents bring in fresh air). It took much longer, but the trees of the period gradually choked themselves out by pulling too much carbon out of the air. It just had to happen on a planetary scale and geologic time frame.
mannykannot 9y ago
Even if the current situation is a global optimum in the sense you propose, it would be purely coincidental, as evolution doesn't do global optimization or long-term planning, and prey does not adapt for the convenience of its predators.
- Symmetry 9y ago
  For an illustration see the Great Oxygen Catastrophe. https://en.wikipedia.org/wiki/Great_Oxygenation_Event https://en.wikipedia.org/wiki/Great_Oxygenation_Event
- jdonaldson 9y ago
  Everything in evolution is coincidental though, right? It's all about simple survivability of traits. If one of the traits introduces an imbalance (at a micro/macro level), it'll eventually sort itself out.
  - mannykannot 9y ago
    I think I see what you are getting at, in that the mutations that initiate each evolutionary step are random, but selection is not random. It is not a coincidence that Impalas and Cheetahs can run at about the same speed, and it is not a coincidence that Pronghorns can run as if they were prey for Cheetahs, as until relatively recently, they were. This does not mean that every coincidence in biology has an evolutionary origin.
    - jdonaldson 9y ago
      That's true... it's impossible to say what's a coincidence and what's not with respect to a given predator/prey relationship. Usually you see a pretty fair match up though. I always think it's interesting when you see a species that is seemingly over-engineered for the purposes of hunting or staying alive: http://www.bbc.com/earth/story/20151014-superpowers-of-the-near-invincible-velvet-ant http://www.bbc.com/earth/story/20151014-superpowers-of-the-n... http://www.newsweek.com/orcas-killing-great-white-sharks-eating-livers-607002 http://www.newsweek.com/orcas-killing-great-white-sharks-eat...

BurritoAlPastor 9y ago

Why do bones need to decompose? What possible evolutionary pressures could be exerted for traits that aren't expressed until after death? (See also the carboniferous period, before the evolution of wood-decomposing bacteria. 60 million years with no decomposition!)

jdonaldson 9y ago
Don't confuse trait selection for evolutionary pressures. If previous generation exhaust or over-sequester resources it dooms the species that relies on them. The carboniferous period sequestered a huge amount of carbon. That's a process spread across an enormous time frame. But, that was primarily atmospheric carbon, which can be circulated much better than terrestrial minerals. Since it was atmospheric, you wouldn't have localized shortages (air currents bring in fresh air). It took much longer, but the trees of the period gradually choked themselves out by pulling too much carbon out of the air. It just had to happen on a planetary scale and geologic time frame.

mannykannot 9y ago

Even if the current situation is a global optimum in the sense you propose, it would be purely coincidental, as evolution doesn't do global optimization or long-term planning, and prey does not adapt for the convenience of its predators.

Symmetry 9y ago
For an illustration see the Great Oxygen Catastrophe. https://en.wikipedia.org/wiki/Great_Oxygenation_Event https://en.wikipedia.org/wiki/Great_Oxygenation_Event
jdonaldson 9y ago
Everything in evolution is coincidental though, right? It's all about simple survivability of traits. If one of the traits introduces an imbalance (at a micro/macro level), it'll eventually sort itself out.
- mannykannot 9y ago
  I think I see what you are getting at, in that the mutations that initiate each evolutionary step are random, but selection is not random. It is not a coincidence that Impalas and Cheetahs can run at about the same speed, and it is not a coincidence that Pronghorns can run as if they were prey for Cheetahs, as until relatively recently, they were. This does not mean that every coincidence in biology has an evolutionary origin.
  - jdonaldson 9y ago
    That's true... it's impossible to say what's a coincidence and what's not with respect to a given predator/prey relationship. Usually you see a pretty fair match up though. I always think it's interesting when you see a species that is seemingly over-engineered for the purposes of hunting or staying alive: http://www.bbc.com/earth/story/20151014-superpowers-of-the-near-invincible-velvet-ant http://www.bbc.com/earth/story/20151014-superpowers-of-the-n... http://www.newsweek.com/orcas-killing-great-white-sharks-eating-livers-607002 http://www.newsweek.com/orcas-killing-great-white-sharks-eat...