[JohnAaronNelson]

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]

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.

[tigen]

MacLean doesn't say the brain is an onion with a tiny reptile inside!

[jacquesm]

> there are claims that they are largely conserved.

That they're not static doesn't necessarily mean that they aren't largely conserved.

[Retric]

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.

[evv555]

Putting this particular theory aside the generalization that evolution is a nested hierarchy of structures is pretty obvious on the macroscopic level. Traits like breathing oxygen, having symmetrical bodies, backbones, limbs. These are all examples of structures building on top of one another sequentially and conserved across species. Sure each of these subcomponents continues to specialize but the core functionality remains largely the same.

Going back to your analogy saying visual cortex of frog is wildly different from a human visual cortex. That's similar to saying a frog backbone is wildly different from a human backbone. Sure that's true but there's also a shared common core functionality largely conserved across time

[aeternum]

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.

[liquidpele]

> No one thinks the older structures are static.

It would seem enough people did to warrant this person to write about the topic.