Brain expansion (Evolution)

by dhw, Thursday, August 06, 2020, 12:48 (1568 days ago) @ David Turell

DAVID: You've changed emphasis […] …artifact or not, what you wrote was an important new idea that had to be implemented so it caused an enlargement to occur for the actual implementation.

dhw: Correct. What I originally wrote was: “pre-sapiens brains expanded when the capacity was too small to meet new requirements (e.g. the implementation and usage of new means of survival). The expanded brain would suffice for so many thousands of years until it could no longer cope with more advances, and so it expanded again.” What part of my theory has changed?

DAVID: It still interprets as small brain with big new idea needs bigger brain to implement

It means that the brain gets bigger through the process of implementation.

DAVID: Which bigger brained fossil should be accompanied by new advanced artifact. The Moroccan sapiens were not but we see stasis. . And later: Your underlying theory requires a new artifact to appear with the new larger brained fossil.

This is getting silly. I keep repeating that NOBODY KNOWS what caused any of the expansions, and that we used artefacts as a concrete illustration of the process. In the bold above, e.g. means "for example". It does not mean every expansion was caused by the invention of a new artefact! What we see in Moroccan sapiens is the larger brain. We don’t know what caused the larger brain. That is why we have theories. Presumably yours is that one night God stepped in and dabbled with their brains, skulls and pelvises. Any evidence?
[...]

DAVID: you brought up elephant heads, I didn't.

You said that my theory required expansion. I pointed out that if the brain continued to expand indefinitely we would end up with very big heads – the elephant was meant to indicate the size of head we would eventually have, and I think that would mean a few changes to the body. That is why I think complexification had to take over.

Xxxx
On the subject of reading:
QUOTE: "To account for the development of this skill, some scientists have hypothesized that parts of the brain that originally evolved for other purposes have been "recycled" for reading. As one example, they suggest that a part of the visual system that is specialized to perform object recognition has been repurposed […](David’s bold)

DAVID: This finding is a logical extension of what we have learned about our big and formally oversized brain. We have been given a brain that has the ability to repurpose or recycle an area with underlying abilities […]

dhw: For once, we agree. This hypothesis illustrates the point that a new requirement leads to brain change. I don’t think even you would propose that your God altered the visual system BEFORE people thought of reading and writing. (The relevant sections of the illiterate women’s brains complexified when they learned to read, and not before). However, since the system did not lose its original function, I’d say it complexified (perhaps even expanded), not that it was repurposed or recycled. […] But what we do know, and what is supported by the above hypothesis, is that the brain changes as it responds to new requirements and not in anticipation of them. I can only repeat that I see no reason why anyone should assume that the same process was not responsible for complexifications and expansions before and including that of sapiens.

DAVID: No matter what you propose about brain enlargement, all we know is our big brain was present long before it was used in any new way.

Yes, the non-use is what we call stasis. And I wonder why you think your God expanded the brain when he did, if he knew that we weren’t going to use it for 270,000 years. I have pointed out that after each expansion (cause unknown, but maybe new inventions, new requirements caused by changed conditions) there has also been a period of stasis.

DAVID: And it obviously came with a very functional complexification mechanism, causing the brain later to shrink. The whole process appears designed in advance of needs and to handle needs as required over time.

We have agreed that preceding brains would also have complexified. The earlier brain must have been plastic enough both to complexify and to expand, so sapiens brain was/is no different in that respect. Shrinkage is also part of the plasticity – just as the brain could add cells when needed, it could discard cells that were not needed. The whole process of complexification and expansion may go back to the design of a mechanism that enables all organs and organisms to “handle needs as required over time”. I have called it cellular intelligence. Your version used to be divine preprogramming or dabbling, though this has now been thrown into disarray by your theory that evolution has progressed through random mutations which God allows but does not design.