A decent summary of the discussion over shrinkage of brain size in Homo sapiens in the past 100,000 years.
One very strong point is made by Eva #Jablonka, linking reduction of brain size to stratification and class society:
'Jablonka argues that if even if brains did shrink when complex societies emerged, it doesn't necessarily follow that smaller brains were necessarily an adaptive response.
"If 3,000 years ago much larger more complex societies emerged, this could correlate with much greater differences in social classes. If, as a consequence the majority of people were poor, then we know that poverty and malnutrition and things like that would compromise the developing brain."'
We would agree, metabolic and energetic/nutrient constraint is likely important. Marta #Lahr also suggests a link to nutrient deficiency associating to onset of agriculture.
A significant implication is that the super large brains of our ancestors came about through #egalitarianism and strong ethics of #sharing vital nutrients to mothers and children.
