Sex on Six Legs_ Lessons on Life, Love, and Language From the Insect World - Marlene Zuk [36]
The Face Is Familiar, but the Sting Is Different
IMPLICIT in the existence of different personality types is the ability to tell each other apart. If you can't keep track of whom you're dealing with, knowing that someone is rude and someone else magnanimous is useless. Young Wart was taken aback by the sameness of the ants he encountered, each distinguishable only by a set of letters and numbers (the Borg, too, were designated by numbers, with the voluptuous Seven of Nine, taken into the Voyager starship community, using her lack of a humanoid name as an indication of her loss of humanity). The implication was that since all the individuals behaved the same, there was no point in distinguishing among them, either by appearance or appellation. And yet if animals have personalities, and others react to them as individuals, they must not be indistinguishable. We can tell our pets apart, and we are perfectly happy to watch nature shows that differentiate—and name—individual elephants or meerkats. But what about insects?
One roach or ant may look just like the next to us, but when Liz Tibbetts of the University of Michigan puts up a slide of the paper wasps she studies, she calls the array of face shots portraits, and she does it unselfconsciously. To her, they are just as distinctive as a series of family holiday photos, or a row of oil paintings of ancestors on the manor wall. And indeed, once you scrutinize the lineup, the yellow triangular faces do differ: a couple of black dots across the forehead of one, a big dark triangle across the chin of another. For over a century, conventional entomological wisdom held that given the large numbers of individuals in a social insect colony, the most one could hope for in terms of individual recognition would be a rough ability to classify other wasps (or bees, or ants) into categories: male versus female, or nest mate, to be fed or at least tolerated, versus foreigner, to be attacked. Maybe it is the opposite of anthropomorphism: instead of assuming animals are like us, we assume they are not. Both are risky generalizations that turn out not to be borne out by the facts. Increasingly, biologists such as Tibbetts are discovering that at least some insects can do far more than peer nearsightedly at their neighbor and call it friend or foe.
Paper wasps, unlike honeybees, live in relatively small groups of females, all of which are capable of laying eggs, so they lack the clear distinction between worker and queen. The females of one of the species Tibbetts studies, Polistes fuscatus, fight vigorously for dominance at the beginning of the season. The rank an individual attains is crucial, because the higher up a wasp is in the hierarchy, the more food she can garner, the less work she does, and, most important, the more eggs she contributes to the colony's reproduction, giving her a larger share of genes in the next generation. But Tibbetts noticed that, as with other species that live in socially stratified groups, for example, baboons, the overall amount of aggression in a wasp nest subsides with time, and the wasps do not have to fight each time they meet to reestablish who's boss.
Tibbetts suspected that the wasps used their variable facial patterns to recognize and remember individuals, and she tested her idea in an ingenious if simple way: she painted the faces of wasps so that they no longer seemed familiar to their nest mates. To minimize her risk of getting stung, she nabbed the wasps early in the morning, when the wasps were chilly and less inclined to object to being handled. Once the redecorated insects were returned to their nests, Tibbetts watched the reaction of the rest of the colony. As she had predicted, the wasps were much more aggressive to the altered individuals than they had been before, although the aggression subsided after about half an hour, indicating that they had learned