Monkeying With Ideas
Biology has traditionally parceled the human brain into two regions: the “new brain” or “neocortex,” where reason and analysis reside, and the old or “lower” brain, which reacts to environmental events in a simple, stimulus-response fashion that guides the behavior of less-evolved animals. The basic idea is that our lower brain senses a stimulus--say a car horn or a doctor tapping our knee--and then responds reflexively, tensing our back or flexing our leg. Meanwhile our higher brain mulls over the meaning of it all. Simple, easy to grasp and so flattering to humans.
A study published in last week’s issue of the journal Nature, however, casts a critical eye on this simple dualism. Studying macaque monkeys, New York University neuroscientists Michael L. Platt and Paul W. Glimcher found that their “lower” brains were in fact “devoted to subjective evaluation and decision-making.”
Platt and Glimcher shined colored lights, then rewarded the monkeys with fruit juice when they looked at certain colors. After varying the colors and the amount of juice for five years, they found that a portion of the monkey’s parietal lobe thought to merely transform visual signals into eye movements actually kept close track of how much juice each color was worth and chose to “see” only valuable colors.
Far from being the sort of mindless functionary envisioned by traditional biology, the monkeys’ parietal lobes acted more like business executives conducting cost-benefit analyses on proposals, then highlighting only those that could benefit the company.
Philosophers who believe that man is governed primarily by conscious, rational thought are not likely to warm to Platt and Glimcher’s conclusion that monkeys and their fellow primates--humans--are often guided by the same sort of genetic imperatives that influence “lower” animals.
As they weather the inevitable controversies, Platt and Glimcher can find a role model in 77-year-old Caltech professor Seymour Benzer, who launched the field of modern behavioral genetics with his studies of how genes influence behavior in fruit flies. Benzer has often been scorned for suggesting that the same gene sequences that help flies learn, remember and court their mates also influence the way humans behave.
Benzer, however, did what good science requires: Ask interesting questions, devise experiments to answer them and then look closely through unbiased eyes at the result. Benzer began researching flies not to prove some preconceived point but to find out how his two daughters could have been born with such “delightfully different” temperaments. He let himself be guided by scientific curiosity rather than political conviction or the smell of money.
Today, some universities are putting intense pressure on scientists to have specific commercial ends in sight before they even begin their research. It has become more difficult for scientists to follow such a free path.
Benzer’s lifetime of impartial research and the NYU researchers’ five-year study offer important and needed reminders of how much scientists can accomplish when they are freed from the burden of having to meet social or financial expectations and allowed to engage instead in pure discovery.
