Big brain evolution: changes in sapiens skull shape (Evolution)

by dhw, Friday, January 26, 2018, 13:45 (25 days ago) @ David Turell

DAVID: You do not accept my idea that evolution builds on itself. There is no reason to reject the idea that earlier smaller brains never complexified at their level…

Of course I accept that idea! That is the whole basis of common descent. New organisms build on what has been produced by earlier organisms. It is you who keep claiming that evolution does NOT build on itself, and your God has to keep jumping in to expand brains, build nests, change legs into flippers...And I have NEVER rejected the idea that earlier smaller brains complexified. They may well have complexified, until – as stated earlier – “the concept is too complex for the existing capacity”. THEN they have to expand.

dhw: None of this explains your contradictory belief that the SOUL is responsible for new ideas, but pre-sapiens’ SOUL could not have had new ideas until his/her BRAIN had ALREADY expanded.

DAVID: Complex brains provide more complex implementation as shown by artifacts. More complex concepts require the soul using a more complex brain.

The artefacts are the product of the implementation. The more complex the concept (which according to you is the product of the SOUL), the greater the complexity required to implement it, and the illiterate women prove that added complexity is the RESULT of implementation. In pre-sapiens, the same process would have taken place until the capacity of the brain could no longer cope with the complexities of the new concept, and then it had to expand.

Dhw: Once more, the logic is as follows (some of this may sound familiar to you): homimim has an immaterial idea for spears. NO BRAIN CHANGE. As he learns to knapp flint, attach the stone to a wooden rod, throw it with accuracy etc., his brain enlarges with all the muscle movement and coordination involved, so that by the time he is able to perform all these new actions, his brain has expanded to its new size.

DAVID: No way! His brain added complexity just like ours does. Fits the history of evolution.

It would have added complexity until it could no longer cope. The above account shows how the process would have worked once extra abilities were needed – clear cause and effect. It makes no sense for the brain to expand (or to complexify) without a cause! Your hypothesis leaves you with the same contradiction you simply cannot resolve: you say your God expands the brain, and only then can the hominin think of something new, although thought according to you does NOT depend on the brain.


Latest post:
DAVID: Our brains reached their volume/size about 300,000 years ago, and changed from a more oblong shape to a more globular form by the last 40,000 years, as use of the brain altered its lobes:

Precisely: use of the brain means implementation of concepts (which according to you are the product of the soul), and that is what alters the size, the complexity, and now apparently the shape. Thank you.

QUOTE: "In a study published Wednesday in Science Advances, researchers from the Max Planck Institute for Evolutionary Anthropology announced that the earliest Homo sapiens did not have globular brains like we have today. Instead, their brains had a shape intermediate between that of Homo erectus and that of the Neanderthals, both of which were somewhat more elongated horizontally. The brain, the authors write, gradually became globular over evolutionary time, and those changes in turn, induced neurological shifts that coincide with archaeological evidence of modern behavior. (David’s bold)

DAVID’s comment: My bold supports the theory that artifacts show behaviors the brain is capable of producing. As the brain molded itself into slightly new shapes due to lobe developments with new applications and implementations, the skull adapted to the new spatial requirements. The obvious implication is that as the new species of H. sapiens received its new-sized larger brain, it had to spend time learning to use it creating the newer shape. Size first, use second could not be clearer.

As for your bold, I agree that changes COINCIDE with the archaeological evidence. That does not mean the changes preceded the archaeological evidence. The illiterate women’s rewiring coincided with their learning to read and write – because the latter was its cause. And so modern behaviour CAUSES neurological shifts. You even say yourself that the brain molded itself “with new applications and implementations” and you also have the skull adapting itself to the new spatial requirements. New applications and implementations change the brain. The brain does not change beforehand. The nub of the problem is that you keep conflating two separate stages of my hypothesis: 1) The new sapiens size resulted from the implementation of a new concept conceived by the pre-sapiens “soul”, as vividly described in the first section of this post. 2) From then on, the brain could not expand any further, so yes indeed, the new sapiens size preceded all the new concepts that followed, as conceived by the dualistic soul, but implementation took place through complexification, which apparently also caused reshaping as well as shrinkage. So each pre-sapiens expansion resulted from new concepts that exceeded current capacity; from sapiens onwards, new concepts resulted in complexification with shrinkage and reshaping.

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