Brain Expansion (Evolution)

by dhw, Sunday, May 17, 2020, 10:27 (1649 days ago) @ David Turell

dhw: By the time the actual wheel hit the ground rolling, H. sapiens’ brain had ALREADY expanded, and we know that strenuous hard thinking complexifies the sapiens brain. […] We also agree that our brains should reflect the processes undergone by ancient brains. Our brains CHANGE as a result of what you aptly called “hard thinking” and the evolutionary change was from expansion to complexification because for some reason (I offered you a logical one, which you rejected, but you have never offered one of your own)sapiens brain STOPPED expanding.

DAVID: None of the above confusion tells us why the sapiens brain was so large. It was not due to the wheel appearing 5,500 years ago.

At least you have now stopped harping on about shrinkage! There are two unanswered questions: why did brains expand, and why did they stop expanding? I didn’t say expansion was due to the wheel! I said the brain had ALREADY expanded – with ALREADY in block capitals.

DAVID: What I have rejected is the nonsensical perversion that ancient brains acted differently than ours. They each were expanded in stages. They may have had some complexification like ours. That is what I have proposed. You seem to agree. As for the bold, the cause of enlargement, I have said God did it.

My theory simply proposes a continuous line from modern back to ancient: brain CHANGE in response to new requirements. Why is that perverse?

The bold does not relate to the cause of enlargement! It relates to the reason why the brain STOPPED expanding (also in block capitals). So please tell us why you think your God switched from dabbling expansion after expansion to dabbling non-expansion and the complexification takeover.

DAVID: And how does hard thinking get the skull to expand to allow the newly required fit, and the mother's birth canal accommodate the newborn's bigger head?

dhw: You can never seem to get your head round the fact that the body consists of multiple cell communities which cooperate with one another, with or without your God’s 3.8-billion-year computer programme or personal dabbling. Any anatomical change will involve different cell communities cooperating. (David’s red)

DAVID: I understand organs cooperating in life, but not evolution, in which an active positive change in the DNA of germ cells must be required.

Dhw: […] The changes are a fact. How they took place requires a theory. Your theory is that your hands-on God stepped in to dabble with the cell communities of the brain and the skull and the birth canal so that they would cooperate. My theistic proposal is that he gave the cells the intelligence to do it without his interference.

DAVID: The red sentence is totally off the point in evolutionary changes. […] The sentence I've now bolded above in my last reply is the key point about your cooperation theory, and you've totally ignored it or more likely have no answer. Those germ cell's genomes run the show for every expansion of the brain and must be changed to handle all the bony problems I've mentioned attendant to brain enlargement. It is NEVER cell committees cooperation. They are developed from the germ cells instructions to stem cells. Cooperating organs come as a result. Your problem is not recognizing this prior requirement in evolution.

Your problem is that you continue to ignore the fact that organs are cell communities! Of course the genomes must be changed if the organ is to change! You claim your God stepped in to dabble the changes in the genome. I propose that the intelligent cells themselves made the changes. If they did so through germ cells instructing stem cells, then that is how the cooperation took place! How can you have cells giving or obeying instructions without cooperation? Intelligent cell communities within organs cooperate to make the changes through which the organs can cooperate with one another. It’s what Shapiro calls “natural genetic engineering”.

DAVID: The cerebellum is used primarily to coordinate muscular activities, but in humans it has developed other activities.

dhw: I have always been very reluctant to say that there is a rigid division between the functions of the cell communities that make up the brain, as you seem to imply in your post on "Dualism". I prefer to think of the different cell communities within the brain as cooperating and interacting with one another. The article seems to confirm this view.

DAVID: The brain does have different functions in different parts connected by networks of fibers.

Of course. But the example of the cerebellum shows that we cannot necessarily restrict each section to a specific function: e.g. the cerebellum is not confined to muscular activities. Clearly there is interaction and cooperation between the different cell communities within the brain. This has nothing to do with our discussion on dualism, and so I take it we can close that thread, at least for the time being.