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Ancient Fossils Suggest Complex Life Evolved on Land

37 points by digital55 13y ago

leke 13y ago
In the Cosmos series, it seemed to say people came from the sea because of our eye evolution.
- rthomas6 13y ago
  Life != humans. The early land fossils they say they've found were photosynthesizing single-celled organisms, which seem unlikely to have evolved into humans. Also, Cosmos seems more interested in creating an engaging narrative for people with little to no science knowledge than delivering an accurate and complete model that best explains what we currently observe in the world. That's not a bad thing, but I'd take the details they provide as a good basic explanation but not always technically correct. For instance it bothered me when they showed discrete electrons orbiting nuclei. Electrons don't orbit, they exist in a locational probability around the atom in often surprisingly shaped clouds, that is, until observed. But I don't expect a show that's supposed to get people excited about our universe to explain convoluted tangential details that they don't need for the overall point.
- solipsism 13y ago
  That is evidence for the eye evolving in the seas. Knauth's theory is that our progressively more complex ancestors went from the land to the sea to the land. This is still consistent with the eye evolving in the sea.
contingencies 13y ago
Very interesting to me as I live right next to the https://en.wikipedia.org/wiki/Maotianshan_Shales https://en.wikipedia.org/wiki/Maotianshan_Shales which are one of the major sites held to support the alternate, ocean theory. The philosophy of the researcher is admirable, too: In my old age, I am so disappointed that people close their minds and jump on whatever splashy, simplistic bandwagon is in vogue. Perhaps the tech community can learn something from such thinking!
dTal 13y ago
>According to prevailing wisdom, the continents were lifeless, irradiated rock shelves until after the occurrence known as the Cambrian explosion in the seas 540 million years ago, when the precursors to rooting plants and animals burst forth from the ocean to colonize the land. >Taken together, the geochemical and microfossil findings support his theory that during the Precambrian eon, complex life forms evolved not only in the oceans, but also on land. I'm confused. "Cambrian explosion" refers to the development of multicellular organisms, and the resulting geologically-instantaneous biodiversity, not the colonisation of land. Surely the leap to multicellular is a rare event that only happened once. This article seems to be trying to imply that the ocean was not "the cradle of life" in that sense, or that it evolved twice.
- deleted 13y ago
  [deleted]
- dredmorbius 13y ago
  Prevailing wisdom is that plant life emerged on land after the Cambrian explosion, around 542 million years ago (mya). Land plants emerged about 475 mya. That would be "after the Cambrian explosion". Consistent with the wording you're confused over. http://en.wikipedia.org/wiki/Timeline_of_evolutionary_history_of_life http://en.wikipedia.org/wiki/Timeline_of_evolutionary_histor...
transfire 13y ago
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.
- deleted 13y ago
  [deleted]
briantakita 13y ago
“In my old age, I am so disappointed that people close their minds and jump on whatever splashy, simplistic bandwagon is in vogue,” “But if you start with the rocks and work upward to an interpretation, it often reveals a reality that is not the one in vogue.” Kudos to Knauth for having the fortitude to cut through the cultural bias & naysayers in the pursuit of truth.

37 points by digital55 13y ago

leke 13y ago

In the Cosmos series, it seemed to say people came from the sea because of our eye evolution.

rthomas6 13y ago
Life != humans. The early land fossils they say they've found were photosynthesizing single-celled organisms, which seem unlikely to have evolved into humans. Also, Cosmos seems more interested in creating an engaging narrative for people with little to no science knowledge than delivering an accurate and complete model that best explains what we currently observe in the world. That's not a bad thing, but I'd take the details they provide as a good basic explanation but not always technically correct. For instance it bothered me when they showed discrete electrons orbiting nuclei. Electrons don't orbit, they exist in a locational probability around the atom in often surprisingly shaped clouds, that is, until observed. But I don't expect a show that's supposed to get people excited about our universe to explain convoluted tangential details that they don't need for the overall point.
solipsism 13y ago
That is evidence for the eye evolving in the seas. Knauth's theory is that our progressively more complex ancestors went from the land to the sea to the land. This is still consistent with the eye evolving in the sea.

contingencies 13y ago

Very interesting to me as I live right next to the https://en.wikipedia.org/wiki/Maotianshan_Shales https://en.wikipedia.org/wiki/Maotianshan_Shales which are one of the major sites held to support the alternate, ocean theory. The philosophy of the researcher is admirable, too: In my old age, I am so disappointed that people close their minds and jump on whatever splashy, simplistic bandwagon is in vogue. Perhaps the tech community can learn something from such thinking!

dTal 13y ago

>According to prevailing wisdom, the continents were lifeless, irradiated rock shelves until after the occurrence known as the Cambrian explosion in the seas 540 million years ago, when the precursors to rooting plants and animals burst forth from the ocean to colonize the land. >Taken together, the geochemical and microfossil findings support his theory that during the Precambrian eon, complex life forms evolved not only in the oceans, but also on land. I'm confused. "Cambrian explosion" refers to the development of multicellular organisms, and the resulting geologically-instantaneous biodiversity, not the colonisation of land. Surely the leap to multicellular is a rare event that only happened once. This article seems to be trying to imply that the ocean was not "the cradle of life" in that sense, or that it evolved twice.

deleted 13y ago
[deleted]
dredmorbius 13y ago
Prevailing wisdom is that plant life emerged on land after the Cambrian explosion, around 542 million years ago (mya). Land plants emerged about 475 mya. That would be "after the Cambrian explosion". Consistent with the wording you're confused over. http://en.wikipedia.org/wiki/Timeline_of_evolutionary_history_of_life http://en.wikipedia.org/wiki/Timeline_of_evolutionary_histor...

transfire 13y ago

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.
deleted 13y ago
[deleted]

briantakita 13y ago

“In my old age, I am so disappointed that people close their minds and jump on whatever splashy, simplistic bandwagon is in vogue,” “But if you start with the rocks and work upward to an interpretation, it often reveals a reality that is not the one in vogue.” Kudos to Knauth for having the fortitude to cut through the cultural bias & naysayers in the pursuit of truth.