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No one thinks the older structures are static. No one is arguing that. It's a simplified model about the origin. This argument is akin to saying we're not "ne

No one thinks the older structures are static. No one is arguing that. It's a simplified model about the origin. This argument is akin to saying we're not "newer" apes ala > The refutation is of the idea that it’s a strictly chronological ordering of species, with the old species still inside and intact. The correct view is that while homosapiens are indeed mostly "newer", the “older” apes were also modified throughout evolution Obviously.

theptip 3y ago
I mean… the quote from TFA that they are arguing against is > As Paul MacLean (1964), originator of the triune-brain theory, stated, >> man, it appears, has inherited essentially three brains. Frugal Nature in developing her paragon threw nothing away. The oldest of his brains is basically reptilian; the second has been inherited from lower mammals; and the third and newest brain is a late mammalian development which reaches a pinnacle in man and gives him his unique power of symbolic language. And they quote other textbooks that are making claims along these lines too; this is right at the beginning of TFA. So I think you are wrong that “no one thinks that”. Of course they don’t think the old brains are 100% static but there are claims that they are largely conserved.
- jacquesm 3y ago
  > there are claims that they are largely conserved. That they're not static doesn't necessarily mean that they aren't largely conserved.
- tigen 3y ago
  MacLean doesn't say the brain is an onion with a tiny reptile inside!
Retric 3y ago
It’s an incorrect and misleading model about the origin. Bat wings and bird wings share many traits but the common answer didn’t fly it’s simply convergent evolution. The brain structures of that same common ancestor is only vaguely related to modern structures in mammals and reptiles. Modern reptiles, birds, and humans have experienced the same amount of evolution. There’s similar traits, but we don’t call whale flippers hands because that’s what the structures was in some of their ancestors or even what it is in related species. Similarly we don’t call human hands flippers because that’s what the structure started out as even further back and it’s still preforming that function in modern fish. The human visual cortex is larger than most creatures entire brain, it’s a wildly different structure than you find on a frog which plays a wider role in cognition than just decoding vision.
- aeternum 3y ago
  But you could say that whale flippers are 'basically' their hands. Every scientific model and analogy is flawed in some way, but many are still useful.
  - Retric 3y ago
    How exactly is this theory useful? Yes, frogs and humans process visual information because they both have eyes. That’s about all those structures have in common.
    - aeternum 3y ago
      For nearly all of human history everyone thought that those frog vs. human eyes were completely separate and designed by some magical being living up in the cloud. By noticing that while they have significant differences, those structures also have significant similarities, we were able to correctly answer one of the greatest questions of all time: where did humans come from? Of all models, this one is particularly useful.
      - Retric 3y ago
        To be useful models must accurately represent some aspect of reality, Reptiles don’t represent the brain of our common assessor particularly well. So this model is just wildly wrong without any predictive power. Compare the giant spheres used by snakes, bird, frog etc to process visual information and try and map that to a rodent, bat, or human. Hint you’re not going to be able to locate an obvious sphere because the fundamental morphology is just different. You can say we both have areas of the brain devoted to processing vision but so do fruit flies.
    - cma 3y ago
      Eyes are a good example of conservation and path dependence, development is initiated by a fairly highly conserved gene: https://en.wikipedia.org/wiki/PAX6#Species_distribution https://en.wikipedia.org/wiki/PAX6#Species_distribution
liquidpele 3y ago
> No one thinks the older structures are static. It would seem enough people did to warrant this person to write about the topic.

theptip 3y ago

I mean… the quote from TFA that they are arguing against is > As Paul MacLean (1964), originator of the triune-brain theory, stated, >> man, it appears, has inherited essentially three brains. Frugal Nature in developing her paragon threw nothing away. The oldest of his brains is basically reptilian; the second has been inherited from lower mammals; and the third and newest brain is a late mammalian development which reaches a pinnacle in man and gives him his unique power of symbolic language. And they quote other textbooks that are making claims along these lines too; this is right at the beginning of TFA. So I think you are wrong that “no one thinks that”. Of course they don’t think the old brains are 100% static but there are claims that they are largely conserved.

jacquesm 3y ago
> there are claims that they are largely conserved. That they're not static doesn't necessarily mean that they aren't largely conserved.
tigen 3y ago
MacLean doesn't say the brain is an onion with a tiny reptile inside!

Retric 3y ago

It’s an incorrect and misleading model about the origin. Bat wings and bird wings share many traits but the common answer didn’t fly it’s simply convergent evolution. The brain structures of that same common ancestor is only vaguely related to modern structures in mammals and reptiles. Modern reptiles, birds, and humans have experienced the same amount of evolution. There’s similar traits, but we don’t call whale flippers hands because that’s what the structures was in some of their ancestors or even what it is in related species. Similarly we don’t call human hands flippers because that’s what the structure started out as even further back and it’s still preforming that function in modern fish. The human visual cortex is larger than most creatures entire brain, it’s a wildly different structure than you find on a frog which plays a wider role in cognition than just decoding vision.

aeternum 3y ago
But you could say that whale flippers are 'basically' their hands. Every scientific model and analogy is flawed in some way, but many are still useful.
- Retric 3y ago
  How exactly is this theory useful? Yes, frogs and humans process visual information because they both have eyes. That’s about all those structures have in common.
  - aeternum 3y ago
    For nearly all of human history everyone thought that those frog vs. human eyes were completely separate and designed by some magical being living up in the cloud. By noticing that while they have significant differences, those structures also have significant similarities, we were able to correctly answer one of the greatest questions of all time: where did humans come from? Of all models, this one is particularly useful.
    - Retric 3y ago
      To be useful models must accurately represent some aspect of reality, Reptiles don’t represent the brain of our common assessor particularly well. So this model is just wildly wrong without any predictive power. Compare the giant spheres used by snakes, bird, frog etc to process visual information and try and map that to a rodent, bat, or human. Hint you’re not going to be able to locate an obvious sphere because the fundamental morphology is just different. You can say we both have areas of the brain devoted to processing vision but so do fruit flies.
  - cma 3y ago
    Eyes are a good example of conservation and path dependence, development is initiated by a fairly highly conserved gene: https://en.wikipedia.org/wiki/PAX6#Species_distribution https://en.wikipedia.org/wiki/PAX6#Species_distribution

liquidpele 3y ago

> No one thinks the older structures are static. It would seem enough people did to warrant this person to write about the topic.