Are We Smart Enough to Know How Smart Animals Are?(78)

Male cuttlefish courting a female may trick rival males into thinking there is nothing to worry about. The courting male adopts the coloring of a female on the side of his body that faces his rival, so that the latter believes he is looking at a female. But the same male keeps his original coloring on the female’s side of his body in order to keep her interested. He thus courts her surreptitiously. This two-faced tactic, called dual-gender signaling, suggests tactical skills of an order that we might expect in primates but not mollusks.30 Hanlon rightly claims that cephalopod truth is stranger than fiction.

Invertebrates will probably continue to challenge students of evolutionary cognition. Being anatomically quite different yet facing many of the same survival problems as the vertebrates, they offer fertile grounds for convergent cognitive evolution. Among the arthropods, for example, we find jumping spiders known to trick other spiders into thinking that their web contains a struggling insect. When the web-owner hurries over for the kill, she herself becomes the prey. Instead of knowing at birth how to enact a trapped insect, jumping spiders seem to learn how to do so by trial and error. They try out a kaleidoscope of random pluckings and vibrations on the silk of another spider, using their palps and legs, while taking note which signals best lure the owner toward them. The most effective signals will be repeated on future occasions. This tactic allows them to fine-tune their mimicry to any victim species, which is why arachnologists have begun to speak of spider cognition.31

And why not?


When in Rome

To our surprise, chimps turn out to be conformists. Copying others for one’s own benefit is one thing, but wanting to act like everybody else is quite another. It is the foundation of human culture. We discovered this tendency when Vicky Horner presented two separate groups of chimpanzees with an apparatus from which food could be extracted in two different ways. The apes could either poke a stick into a hole to release a grape or use the same stick to lift up a little trap and a grape would roll out. They learned the technique from a model: a pretrained group member. One group saw a lifting model, the other a poking model. Even though we used the same apparatus for both groups, moving it back and forth between them, the first learned to lift, and the second to poke. Vicky had created two distinct cultures, dubbed the “lifters” and the “pokers.”32

There were exceptions, though. A few individuals discovered both techniques or used a different one than their model had demonstrated. When we retested the chimps two months later, though, most of the exceptions had vanished. It was as if all the apes had settled on a group norm, following the rule “Do what everyone else is doing regardless of what you found out by yourself.” Since we never noticed any peer pressure nor any advantage of one technique over the other, we attributed this uniformity to a conformist bias. Such a bias obviously fits my ideas about imitation guided by a sense of belonging as well as what we know about human behavior. Members of our own species are the ultimate conformists, going so far as abandoning their personal beliefs if they collide with the majority view. Our openness to suggestion goes well beyond what we found in the chimps, yet it seems related. This is why the conformist label stuck.33

It is increasingly applied to primate culture, such as by Susan Perry in her fieldwork on capuchin monkeys. Perry’s monkeys have two equally efficient ways of shaking the seeds out of the Luehea fruits that they encounter in the Costa Rican jungle. They can either pound the fruits or rub them on a tree branch. Capuchins are the most vigorous and enthusiastic foragers I know, and most adults develop one technique or the other but not both. Perry found conformism in daughters, who adopted the preferred method of their mothers, but not in sons.34 This sex difference, also known of juvenile chimpanzees learning to fish for termites with twigs, makes sense if social learning is driven by identification with the model. Mothers act as role models for daughters but not necessarily for sons.35

Conformism is hard to substantiate in the field. There are too many alternative explanations for why one individual might act like another, including genetic and ecological ones. How these issues can be resolved was shown by a large-scale project on humpback whales in the Gulf of Maine in the northeastern United States. In addition to their regular bubble-feeding, in which whales drive fish together with air bubbles, one male invented a new technique. First seen in 1980, this whale would whack the ocean surface with his fluke to produce a loud noise that clumped the prey even more. Over time this lobtail technique became increasingly common in the population. In the course of a quarter-century, investigators carefully plotted how it spread across six hundred individually recognized whales. They found that whales who had associated with those employing the technique were more likely to use it themselves. Kinship could be ruled out as a factor, because whether a whale had a lobtail-feeding mother hardly mattered. It all boiled down to whom they had encountered while feeding on fish. Since large cetaceans are unsuitable for experiments, this may be as close as we will ever get to proving that a habit spread socially as opposed to genetically.36

On wild primates, experimental work is rare for different reasons. First of all, these animals are neophobic, and rightly so, because imagine the danger of freely approaching human contraptions, including those set by poachers. Second, fieldworkers generally hate to expose their animals to artificial situations, since their goal is to study them with as little disturbance as possible. Third, they have no control over who participates in an experiment and for how long, thus precluding the kind of tests typically applied to animals in captivity.