The Incredible Growing Brain

| July / August 2006

Science, it seems, is always butting heads with some deeply entrenched, and abstractly comforting, human belief. It disproved our tidy assumption that Earth is the center of the universe. It has forced us to get comfortable being the descendants of apes and the genomic equivalent of mice. And now, in a particularly damaging blow to our feel-good beliefs about the democracy of human effort, science has another whopper: When it comes to brain development, the playing field isn't equal.

'Boring environments, stressful noises, and the primate's particular slot in the dominance hierarchy all shape the architecture of the brain,' reports Jonah Lehrer in Seed (Feb./March 2006). 'Poverty and stress aren't just an idea: They are an anatomy. Some brains never even have a chance.'

This radical new hypothesis is based on the nascent, but increasingly irrefutable, science of neurogenesis, the process by which the brain creates new neurons. Until recently, modern neuroscience was predicated on the idea that all brain neurons emerge during prenatal and early postnatal development, and the number of brain cells is then fixed for life. But the research of Elizabeth Gould, a professor of psychology at Princeton University, turned that theory on its head.

Her laboratory's observation of marmosets demonstrated that 'the primate brain is always creating new neurons,' reports Lehrer. What's more, her team went on to prove that 'the structure of our brain . . . is incredibly influenced by our surroundings. Put a primate under stressful conditions, and its brain begins to starve. It stops creating new cells. The cells it already has retreat inward. The mind is disfigured.'

The implications of Gould's observations are monumental. In situations of chronic stress, say, living in impoverished conditions or being low in a dominance hierarchy, the production of neurons stops. No new neural pathways are created, the brain suffers, and the truism that we are all able, through hard work and effort, to achieve congruent levels of mental acumen is kaput.

The takeaway? 'The mind is like a muscle: It swells with exercise,' writes Lehrer. 'Give a primate just a few extra playthings, and its neurons are capable of escaping the downward cycle of stress.'-Laine Bergeson