I’m a little confused. Are you disagreeing that shrinkage took place, or are you disagreeing that brain volume relates to the ability?
From earlier post:
My point with invoking the possibility of such differences was that we are faced with the dilemma of either being right and no systematic difference in ability stems from this systematic and comparably large difference in brain size or the resulting systematic difference in ability has been tiny enough to be either tricky to detect or small enough for us to paper over it and pretend it is not there.
There’s a perfectly good explanation for having well agreed data that the brain volume varies between populations, yet not having well agreed data that intelligence or other functionality varies between populations: it is straightforwardly true that the variation in intelligence is both dramatically easier to paper over AND we’d be more inclined to paper it over, than craniometry. Ten percent difference between brain volumes can’t be papered over. Ten percent difference in any intelligent function easily can.
Basically, the data we have on intelligence (or tendency towards religious craziness) across ethnic groups is utter and complete garbage. That is not same thing as having evidence for zero variation.
edit: that is to say:
I do not believe that if there was 10% variation of some function across races or genders, such a difference would be reliably agreed upon.
If you take IQ test of same person twice—or take two different tests—there’s much, much less agreement than if you do craniometry using MRI or between different MRI machines or between different methods of doing craniometry. That is to say, our intelligence-sensor got dramatically larger error than our brain-volume sensor, and the data from intelligence sensor would be judged inconclusive for same degree of difference for which the MRI data would be judged nearly indisputable.
In light of this, lack of agreement on this topic constitutes very poor evidence in favour of zero variation of intelligence or it’s various aspects (such as rejecting crazy nonsense). You only stick with zero variation if zero variation is a simplest hypothesis—but independence of intelligence from volume is not a simple hypothesis, but instead a very very surprising one, with potential to overturn much of our understanding of evolution as the larger heads have significant costs.
However, I entirely agree that if we were better able to measure intelligence, and were better able to agree upon the intelligence and its variation across races, then lack of evidence for variation of intelligence and the like across races in presence of variation of brain volume would constitute significant evidence in favour of independence of intelligence and other related functions from brain volume.
I’m a little confused. Are you disagreeing that shrinkage took place, or are you disagreeing that brain volume relates to the ability?
From earlier post:
There’s a perfectly good explanation for having well agreed data that the brain volume varies between populations, yet not having well agreed data that intelligence or other functionality varies between populations: it is straightforwardly true that the variation in intelligence is both dramatically easier to paper over AND we’d be more inclined to paper it over, than craniometry. Ten percent difference between brain volumes can’t be papered over. Ten percent difference in any intelligent function easily can.
Basically, the data we have on intelligence (or tendency towards religious craziness) across ethnic groups is utter and complete garbage. That is not same thing as having evidence for zero variation.
edit: that is to say:
I do not believe that if there was 10% variation of some function across races or genders, such a difference would be reliably agreed upon.
If you take IQ test of same person twice—or take two different tests—there’s much, much less agreement than if you do craniometry using MRI or between different MRI machines or between different methods of doing craniometry. That is to say, our intelligence-sensor got dramatically larger error than our brain-volume sensor, and the data from intelligence sensor would be judged inconclusive for same degree of difference for which the MRI data would be judged nearly indisputable.
In light of this, lack of agreement on this topic constitutes very poor evidence in favour of zero variation of intelligence or it’s various aspects (such as rejecting crazy nonsense). You only stick with zero variation if zero variation is a simplest hypothesis—but independence of intelligence from volume is not a simple hypothesis, but instead a very very surprising one, with potential to overturn much of our understanding of evolution as the larger heads have significant costs.
However, I entirely agree that if we were better able to measure intelligence, and were better able to agree upon the intelligence and its variation across races, then lack of evidence for variation of intelligence and the like across races in presence of variation of brain volume would constitute significant evidence in favour of independence of intelligence and other related functions from brain volume.