Introducing the brain: half a brain is just fine (Introduction)

by dhw, Wednesday, March 11, 2020, 11:54 (1508 days ago) @ David Turell

dhw: For the umpteenth time: you have agreed over and over again that shrinkage has been caused by the efficiency of complexification. I have suggested that this had to take over from expansion, because further expansion would have been a threat to the whole human anatomy. Nevertheless, the modern brain does enlarge itself in small sections. It is therefore perfectly logical to suggest that in the past, when expansion was not a threat to the anatomy, it was caused in exactly the same way as modern expansion and/or complexification is caused: namely by the actions performed in the implementation of concepts, desires, plans etc.

DAVID: Again a total distortion to save a pet theory. The first assumption has to be that our brain has processes developed from past brains and uses them in more complex ways.

Yes indeed, and since our modern brain follows processes of complexification and expansion (though now only on a minor scale) in response to – but not in anticipation of – new concepts, desires, plans etc., it is perfectly logical to assume that past brains did the same.

DAVID: Your theory that the brain stopped enlarging because of anatomic size considerations is simply a wild guess, lacking any evidence for the point.

If the brain had continued to expand, we would have had elephantine heads! Expansion had to stop somewhere! That is not a wild guess – it is a logical assumption. What is your explanation for the end of expansion and the takeover by complexification?

DAVID: Remember our brain was 150 cc larger in the past causing no anatomic trouble.

On and on you go about shrinkage. And yet later you say: “Of course I agree with shrinkage from complexification”. I have asked you repeatedly to give us your own theory about shrinkage, plus any additional facts that you have to back it, but you obviously haven’t got any. See later.

DAVID: Our brain arrived about 315,000 years ago and really began its 'implementation' process (your concept as to how the brain is affected) most actively with language 50-70,000 years ago, and as more an more 'implementation' has occurred in the past 35.000 years it shrunk 150 cc. (about five ounces) That is the factual evidence we have to work with, and we both note tiny enlargements in heavily used regions. That is a logical change in our brain.

Yes, both complexification and enlargement come from usage, not in anticipation of usage. The exact opposite of your theory that your God enlarged the brain before conceptualization and implementation. And it is not implementation that has shrunk the brain, but the fact that the efficiency of complexification has made a certain amount of the brain’s capacity superfluous. All perfectly logical.

DAVID: In fossil brains the usage was never as intensive as today yet we know 200 cc jumps in volume occurred. Your strange theory does not hold water in any sense, and your paragraph above offers nothing to save it.

Our brains are the accumulation of all past concepts and all past expansions plus our own new concepts. That is why I propose that the brain eventually had to stop expanding, as above, and complexification took over, and was so efficient etc. etc. ad nauseam.

dhw If you have decided that after all you don’t accept the explanation you have already agreed on (it has shrunk because of the efficiency of complexification), please tell us your own explanation. Starting point: you believe your God kept enlarging the brain so that it could think up new ideas (although as a dualist you firmly believe that the soul and not the brain does the thinking). So if you think he preprogrammed shrinkage 3.8 billion years ago, or stepped in to dabble it, please explain why you think he did so.

DAVID: Please remember I have no knowledge of God's reasons.

You believe your logical God did it, and you can’t think of a single reason why he would have done so.

DAVID: Of course I agree with shrinkage from complexification. My argument and belief based on facts has never changed. Heavy usage shrinks modern brains.

Heavy usage causes complexification and minor enlargement, and once more: complexification is so efficient etc. ad nauseam. If an organ or part of an organ is no longer required, it is not unnatural for it to disappear. You could hardly have a more logical explanation. But you think your God made our brains larger than necessary and preprogrammed or dabbled shrinkage, and you have no idea why.

DAVID: Light use in habilis and erectus saw brains make large jumps in size. The comparisons don't fit, unless God as an agency is at work. Then of course you can ignore all the facts and daydream as an illogical distortion of them.

Please note that in my theory it was a new "heavy use" that caused the brain to expand - just as it does today, though on a lesser scale. Now please tell me what facts I have ignored or distorted, what additional facts you have to support your theory of divine preprogrammming or dabbling in advance of the need for expansion, and please do make an effort to understand why your God might have preprogrammed or dabbled shrinkage as well. You keep saying he thinks logically, but how do you know that if you can't understand his logic?