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

by David Turell , Wednesday, February 19, 2020, 19:08 (1520 days ago) @ dhw

dhw: Once more you are trying to defend your whole evolutionary thesis that your God preprogrammed or dabbled every new step before it was required. You simply ignore the one fact we know about brain development, which is that the brain RESPONDS to new needs through complexification and even enlargement of individual sections, and does not change in anticipation of them. All brains have to be plastic, or they could not learn, remember, communicate, devise survival strategies etc. You now force me to repeat my proposal: 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 thousand years until it could no longer cope with more advances, and so it expanded again. It reached maximum capacity with H. sapiens (further enlargement would damage the rest of the body), and so complexification took over, and this proved so effective that there was even some shrinkage. Development then took the form of complexification, because every change, as we know for a fact, is a RESPONSE to usage, and not a preparation. We do not know of any “development in advance of usage”!

DAVID: I can accept the entire story, reflecting its Darwinian presuppositions, as showing the requirements for advancement, but produces no explanation for why the brain size jumped 200 cc each time a more advanced fossil species arrived. Your proposal requires tiny changes a la' Darwin's inadequate theory.

You quote my theory and then you ignore it! I have bolded the relevant section. The proposal does NOT require tiny changes. The brain expanded when it could no longer cope with new requirements.

Totally illogical. Assuming an early hominin brain, how did it know what was newly needed so it could force expansion? The spear is invented only after the brain is already expanded and the new idea is developed from its new complexity and new ability to invent. Bass-ackward. The new sized brain dose not come with built-in concepts. They have to be originated with the new ability to think more deeply.

DAVID: Of course with a more complex life style/requirements the brain MUST be bigger. Our discussion is how it happens. Note, only after large gaps in size, which you really never explain by simply saying the jump was needed.

dhw: I have explained the jumps over and over again, and I have explained why they happened (new requirements required a greater capacity). How the jumps happen is a different subject. Your theory is that 3.8 billion years ago your God provided the first cells with a programme for brain jumps - along with every life form, econiche, natural wonder for the rest of time – or he popped in every few thousand years to add 200 cc, because for some inexplicable reason he knew H.sapiens (the only species he really wanted) would need about 1400 cc but decided to do it in stages. My proposal is that the cell communities of which all organisms are composed followed precisely the same pattern we observe in the modern brain, and adjusted themselves to new requirements. And even today, complexification is accompanied by expansion in certain sections, according to the requirements of individuals.

Same weird argument in the bold. A finished product in the modern brain is not an example of an earlier brain and how it formed. Enlarged area now developed from current requirements and are tiny compared to the enlargements of 200 cc's in past jumps in size. The concept of plasticity, cannot be used as an overall theory of enlargement. Plasticity probably existed in all stages of brain size, but simply is a system of localized complexification/enlargement within a brain of a specific fixed size, as shown in our brain. You should remember our brain has actually shrunk 140 cc in the past 30,000 years!!! While certain areas in some individuals (London taxi drivers) do enlarge with use.