Katharine Milton is a tropical party crasher. For 25 years, she has spied on the monkeys of Barro Colorado Island in Panama, watching them as they dine, and bagging their leftovers. Now she's sorted through her logbooks and come to a distressing conclusion: The monkeys have a more balanced diet than we do.
Milton, an ecologist at the University of California at Berkeley, found that an average 15-pound howler monkey far exceeds the National Research Council's recommended dietary allowances for a 150-pound human--which Americans often don't meet. For example, the typical monkey's daily diet includes 600 milligrams of vitamin C, compared with a recommended 60 milligrams for an adult man. The animals also consume much more calcium, potassium, magnesium, fiber, and protein relative to body mass.
"Primates in general are very selective feeders. Even a hungry monkey will not take a leaf or a fruit that it knows, through chemical cues, is not a satisfactory item of diet," says Milton. She has observed monkeys bite amino acid-rich tips off young leaves and discard the rest.
Milton is still trying to figure out exactly why monkeys need to eat so well, but she has a pretty good idea why we eat so poorly. Basically, we've forgotten how to be choosy. Our hedonistic impulses get in the way of proper dietary behavior. "Many Americans are not eating as well as their great-grandparents did in this country," she says.