If You’re So Smart,
Why Aren’t You Rich?
Learning on Six Legs
THE FAMOUS eighteenth-century naturalist Jean-Henri Fabre meticulously examined the mason bees of his native France, marveling at the tiny clay cells they constructed as cradles for their helpless larvae. When the young bee is ready to emerge, under the normal scheme of things it scissors its way out of the clay with its mandibles and squeezes through the opening. But Fabre, like calculating scientists before and after him, tested the ability of the bees to think by examining how they were able to overcome various manipulations of their chambers. First, he thwarted a bee by removing part of the clay and replacing it with a piece of paper. Undaunted, it sliced through the paper with the same motions it used for the thicker material. Then Fabre presented the young bee with not one, but two barriers: the usual clay, and paper a half inch in front of it, so that the insect needed to repeat the motion it had performed on the original cell on the paper. This it was unable to do, instead tapping fruitlessly at the paper it was completely capable of cutting through. Two barriers are never found in nature, and the bee couldn’t perform acts outside its repertoire; we now know that it lacks the kind of neurological GPS (“if a new roadblock appears, repeat steps A through G until you see air”) necessary to adapt to altered circumstances. Fabre tut-tutted over the bee’s ineptitude, noting, “The insect would have to repeat the act which it has just accomplished, the act which it is not intended to perform more than once in its life; it would, in short, have to make into a double act that which by nature is a single one; and the insect cannot do this, for the sole reason that it has not the wish to. The Mason-bee perishes for lack of the smallest gleam of intelligence.”
Later scientists were equally condescending, noting with belittling superiority that although quite a few kinds of insects can perform remarkable tasks, they cannot learn from experience the way we humans can. In the late nineteenth century, the English physician David Douglas Cunningham was posted to the Indian Medical Service in Calcutta, where in addition to studying the pathology of infectious diseases he made detailed observations of the local flora and fauna, including the many large and easily observed insects. He was prepared to admit that some of the large wasps that provisioned their young with paralyzed caterpillars and other prey possessed something along the lines of what he termed intellect, given their complex behavior. But he was also fond of performing “practical jests” on the wasps. The females built mud nests on many objects, including the pipes in his study, and Lieutenant Colonel Cunningham enjoyed occasionally moving the pipe a foot or two from its original location while a wasp was out foraging for prey. He noted that it was then “amusing to observe the astonishment of its tenant when she returns to find her nest gone, and wanders round in perplexity until it is replaced and joyfully recognized.” One could certainly wonder about how hard up for amusement one has to be before taking up playing jokes on wasps, but regardless, the same note of self-satisfaction creeps into Cunningham’s writing that is seen in the writings of most of the early naturalists. Not being able to find something after it was moved, or being unable to recognize a novel feature in the environment must mean that insects, regardless of their awe-inspiring abilities to construct elaborate hives and find flowers miles away, are dimwitted at heart.
But in fact, it is turning out that here too our faith in our uniqueness may be misplaced, and that insects are capable of feats of intelligence that qualitatively, at least, may be quite similar to our own. This finding has many useful implications, from the construction of better computers and robots to a potential cure for brain damage. And it also challenges our ideas about what our own enormous brains might be for.
THE LIKELIEST candidates for insect intelligence, or at least the first ones to be considered by naturalists, have always been the bees, wasps, and ants. Partly this is because we see them more—in our gardens and kitchens—and they seem to be doing things, such as finding food and taking it back to their nest or hive, that require something resembling reasoning. Partly it is because of the sociability of many species, since we use our own intelligence to interact with each other so much. And partly, I think, it has something to do with the way that such insects use objects in their environment, whether it is to build paper cells from chewed wood pulp or to remove pollen from flowers and cram it into the built-in shopping bags on a bee’s leg. Animals that have possessions seem smarter, somehow, which may be a comment on our own valuing of material goods.
Fabre, Cunningham, and a host of other naturalists paid particular attention to the provisioning wasps and bees. These relatives of yellow jackets and honeybees do not live in social groups with a queen and workers. Instead, once she has mated, a single female searches for prey such as caterpillars or large toothsome spiders. After capturing the item, she stings it so that it is paralyzed but not dead, a kind of suspended animation refrigeration system. She lugs her victim to her nest, which may be a burrow in the soil or a custom-built cell on the surface of an object, as with the pipe-loving butts of Cunningham’s “jests,” and lays an egg on it. After the egg hatches, the young larva has a ready food supply that won’t spoil. Depending on the species, the mother may return many times to add prey to supplement the larder or to lay more eggs in additional chambers.
While grisly in certain respects, the wasp’s behavior undeniably requires two of the prerequisites for intelligence: learning and memory. The mother wasp has to remember where her burrow is, find the correct size and number of prey—in one species, the number of food items brought back to the nest is calibrated to the needs of the hungry waiting larvae—and go back to the correct place. All of this has cannot be done purely by rote, because each nest is built anew, each cell provisioned separately, and each prey item puts up a different fight. The wasps seem to use landmarks to find their nests, like remembering where one’s house is by recalling the location of the Starbucks at the corner, and if the landmarks are moved, the wasps fly around the area, like the agitated subjects of the jokes played by Cunningham. In their defense, incidentally, one wonders how most of us would do if we suddenly found the aforementioned coffee shop lifted in its entirety off of the block, between one latte and the next, and whether we too wouldn’t mill around the area, unable to believe our eyes.
Even more impressive than the ability of these wasps is that of another species of wasp that exploits the provisioning kind. These parasites do not care about the wasp larvae waiting for their paralyzed meal, but about the caterpillars that are brought to the larder. Instead of going out and hunting down their own prey, the parasitic wasps capitalize on the food brought in by the hunters and lay their own eggs on the item. The problem is that only a very narrow window of opportunity to lay an egg on the caterpillar exists, which is during the time that the caterpillar is being dragged into the nest by the wasp that first captured it. So instead of trusting to luck to find a host at exactly the right moment, the parasitic wasp performs a reconnaissance mission, flying around areas where the provisioning wasps are likely to be digging their nests, an ...