My last post on David Brooks, conservatism and neuroscience inspired a spirited debate. I argued that the discoveries of modern neuroscience seem to support liberal public policies focused on reducing levels of inequality:
While conservatives tend to regard poverty as primarily a cultural issue, solvable by increasing marriage rates and transitioning people to minimum wage jobs, this research suggests that the symptoms of poverty are not simply states of mind; they actually warp the mind. The truth of the matter is that our neurons are designed to reflect their circumstances, not to rise above them. As a result, the monotonous stress of living in a slum literally limits the brain. Our societal inequality leads to very real neural inequalities.
Some people disagreed. They argued that trying to erase inequality is a Sisyphean task, doomed to failure:
To the extent that providing equally favorable environments to children will lift those who are in squalor to a higher level, this will exacerbate the role that genetic differences play in creating inequality: the less a variable varies (i.e., the environment in a social engineering situation), the less it can account for variance in outcomes. Assuming we don’t also genetically engineer kids, then genetic variance will remain, and the ratio of genetic to environmental variance will increase.
That’s all true. Inequality is writ into the fabric of life. Natural selection, after all, requires random variation among individuals in order to work. That variation leads to genetic inequalities. People are different, and trying to make them all the same is impossible. Nature doesn’t subscribe to Communism.
But here’s where I part company with the Francis Galtons of the world. I don’t think the stubborn presence of inequality means we should stop trying to erase inequality. In fact, I think modern neuroscience has helped us understand what types of inequality we can prevent and what types of inequality are simply beyond our control. Our brains will never all be the same – the IQ test will always have a bell-shaped distribution – but we now know how to provide every brain with the opportunity to reach its full genetic potential.
The good news is that it doesn’t take much. For example, the lab of Elizabeth Gould placed marmosets into three different types of environments. The first environment was bare bones. The primates were socially isolated, and provided with a limited assortment of toys. (This, tragically, is “the standard laboratory cage”.) The second group of marmosets was placed in a simple enriched environment. They could occasionally play with other marmosets, swing on some branches, and exercise their curious instincts. The third group of marmosets was placed in the extra-enriched environment. They could forage for food, play all day with an assortment of toys, etc.
After four weeks, the scientists looked to see what had happened to the brains of these three different groups of primates. Did their environment alter their neurons? Absolutely. Monkeys living in the bare bones environment had reduced levels of synaptic protein, fewer dendritic connections, and less complexity in their dendritic trees. Whatever genetic differences there were between the individual marmosets were completely overwhelmed by the limiting effects of their impoverished environment.
But what about the monkeys in either of enriched environments? Was it better to be in the ultra-enriched environment (upper-class) as opposed to the moderately enriched environment (middle-class)?
No differences were detected between the brains of marmosets living in the two differentially complex environments. Our results show that the structure of the adult primate brain remains highly sensitive even to modest levels of experiential complexity. For adult primates, living in standard laboratory housing may induce reversible dendritic spine and synapse decreases in brain regions important for cognition.
This is just one experiment, of course, and no child grows up in a standard laboratory cage. But it does illuminate the ways in which very limited environments, especially when those environments are stressful, strongly constrain the brain. Our genes don’t even have a chance; we are prevented from reaching our full genetic potential. This same phenomenon seems to also be occurring in America:
“The heritability of IQ at the low end of the wealth spectrum was just 0.10 on a scale of zero to one, but it was 0.72 for families of high socioeconomic status. […] The genetic contribution to intelligence therefore differs in different environments […] the same could be said of certain physical attributes such as height, which is heritable when nutrition is not limiting.”
Of course, the mind also needs nutrition. I believe that the richest society in the history of the world should able to ensure that all of its children are provided with the minimal set of enrichments necessary for the developing brain.