4 ms·

I think the fact that all life as we know it is essentially a "bag of water" is pretty conclusive evidence of its origination in water. However, at some point l

I think the fact that all life as we know it is essentially a "bag of water" is pretty conclusive evidence of its origination in water. However, at some point life clearly flirted with the land, so to speak, and thus there would inevitably be an evolutionary track of going back and forth as organisms become more able to go without sources of water for longer and longer periods. The evolution of amphibians follows the same pattern. So I think it is erroneous and sensationalist to say "fossil evidence suggests complex life evolved on land". It would be more accurate to say something like "early life may have evolved on land more than scientists had previously realized".

ekianjo 13y ago
> "fossil evidence suggests complex life evolved on land" Yeah, and it's survival bias as well, because by definition you don't get much fossils in water. And by far there's way more diversity of life in water so that would suggest clearly otherwise than what the title suggests.
- dredmorbius 13y ago
  you don't get much fossils in water Quite the contrary. Much of the early fossil record consists of remains from shallow seabeds where you had both 1) ample life and 2) persistent sedimentation which would bury and fossilize remains. Those seabeds frequently ended up on land, and not infrequently on mountains, a fact which itself had a strong influence on modern understandings of global biological and geological history. The article (which you clearly didn't read) actually makes that point explicitly: Marine fossils are protected by layers of marine sediment and the quietude of ocean deeps. Land fossils are much more likely to have been pulverized by changing climates and erosion long before paleontologists could have chanced upon them. The fossil record, therefore, is heavily weighted toward the seas, making it appear that they were the cradle of life.
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ekianjo 13y ago

> "fossil evidence suggests complex life evolved on land" Yeah, and it's survival bias as well, because by definition you don't get much fossils in water. And by far there's way more diversity of life in water so that would suggest clearly otherwise than what the title suggests.

dredmorbius 13y ago
you don't get much fossils in water Quite the contrary. Much of the early fossil record consists of remains from shallow seabeds where you had both 1) ample life and 2) persistent sedimentation which would bury and fossilize remains. Those seabeds frequently ended up on land, and not infrequently on mountains, a fact which itself had a strong influence on modern understandings of global biological and geological history. The article (which you clearly didn't read) actually makes that point explicitly: Marine fossils are protected by layers of marine sediment and the quietude of ocean deeps. Land fossils are much more likely to have been pulverized by changing climates and erosion long before paleontologists could have chanced upon them. The fossil record, therefore, is heavily weighted toward the seas, making it appear that they were the cradle of life.

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