There is a new paper out in Nature Neuroscience, mainly by Kimberly Noble, on socioeconomic variables and and brain structure: Family income, parental education and brain structure in children and adolescents. They found that cortex area went up with income, although more slowly at high incomes. Judging from their comments to the press, the authors think that being poor shrinks your brain.
Of course, since intelligence is highly heritable, and since people in higher social classes, or with high income, have higher average IQs (although not nearly as high as I would like), you would expect their kids to be, on average, smarter than kids from low-income groups (and have larger brains, since brain size is correlated with IQ) for genetic reasons. But I guess the authors of this paper have never heard of any of that – which raises the question, did they scan the brains of the authors? Because that would have been interesting. You can actually do microscopic MRI.
Even better, in talking to Nature, another researcher, Martha Farah, mentions unpublished work that shows that the brain-size correlation with SES is already there ( in African-American kids) by age one month!
Of course, finding that the pattern already exists at the age of one month seriously weakens any idea that being poor shrinks the brain: most of the environmental effects you would consider haven’t even come into play in the first four weeks, when babies drink milk, sleep, and poop. Genetics affecting both parents and their children would make more sense, if the pattern shows up so early (and I’ll bet money that, if real, it shows up well before one month); but Martha Farah, and the reporter from Nature, Sara Reardon, ARE TOO FUCKING DUMB to realize this.