Are We Smart Enough to Know How Smart Animals Are? (29 page)

This insight inspired an immensely popular experiment that Sarah Brosnan and I conducted with pairs of brown capuchins. After they performed a task, we rewarded both monkeys with cucumber slices and grapes after determining that they all favored the latter over the former. The monkeys had no trouble with the task if they received identical rewards, even if they both got cucumber. But they were vehemently opposed to unequal outcomes, if one got grapes and the other got cucumber. The cucumber monkey would contentedly munch on her first slice, but after noticing that her companion was getting grapes, she would throw a tantrum. She’d ditch her measly veggies and shake the testing chamber with such agitation that it threatened to break apart.
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Refusing perfectly fine food because someone else is better off resembles the way humans react in economic games. Economists call this response “irrational,” since getting something is by definition better than getting nothing. No monkey, they say, should ever refuse food that she’d normally eat, and no human should reject a small offer. One dollar is still better than no dollar. Sarah and I are unconvinced that this kind of reaction is irrational, though, since it seeks to equalize outcomes, which is the only way to keep cooperation flowing. Apes may even go further than monkeys in this respect. Sarah found that chimpanzees sometimes protest inequity that goes the other way. They object not only to getting
less
than the other but also to getting
more
. Grape receivers may reject their own advantage! This obviously brings us close to the human sense of fairness.
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An odd couple of hunters: a coral trout and a giant moray eel prowl together around the reef.

Without going into further details, something encouraging happened in these studies. They were soon extended to other species, including outside the primates. It is always a sign of a field’s maturity when it expands. Researchers who applied inequity tests to dogs and corvids found reactions similar to those of the monkeys.
⁴⁸
Apparently, no species can escape the logic of cooperation, whether it involves the selection of good partners or the balance between effort and payoff.

The generality of these principles is best illustrated by the work on fish by Redouan Bshary, a Swiss ethologist and ichthyologist. For years Bshary has been enchanting us with observations of the interplay and mutualism between small cleaner wrasses and their hosts, the large fish from which the cleaners nibble away ectoparasites. Each cleaner fish owns a “station” on a reef with a clientele, which come and spread their pectoral fins and adopt postures that offer the cleaner a chance to do its job. In perfect mutualism, the cleaner removes parasites from the client’s body surface, gills, and even the inside of its mouth. Sometimes the cleaner is so busy that clients have to wait in queue. Bshary’s research consists of observations on the reef but also experiments in the laboratory. His papers read much like a manual for good business practice. For example, cleaners treat roaming fish better than residents. If a roamer and a resident arrive at the same time, the cleaner will service the roamer first. Residents can be kept waiting since they have nowhere else to go. The whole process is one of supply and demand. Cleaners occasionally cheat by taking little bites of healthy skin out of their client. Clients don’t like this and jolt or swim away. The only clients that cleaners never cheat are predators, which possess a radical counterstrategy: to swallow them. The cleaners seem to have an excellent understanding of the costs and benefits of their actions.
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In a set of studies in the Red Sea, Bshary observed coordinated hunting between the leopard coral trout—a beautiful reddish-brown grouper that can grow to three feet in length—and the giant moray eel. These two species make a perfect match. The moray eel can enter crevices in the coral reef, whereas the trout hunts in the open waters around it. Prey can escape from the trout by hiding in a crevice and from the eel by entering open water, but it cannot get away from the two of them together. In one of Bshary’s videos, we see a coral trout and a moray eel swimming side by side like friends on a stroll. They seek each other’s company, with the trout sometimes actively recruiting an eel through a curious head shake close to the eel’s head. The latter responds to the invitation by leaving its crevice and joining the trout. Given that the two species don’t share the prey with each other but swallow it whole, their behavior seems a form of cooperation in which each achieves a reward without sacrificing anything for the other. They are out for their own gain, which they attain more easily together than alone.
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The observed role division comes naturally to two predators with different hunting styles. What is truly spectacular is that the entire pattern—two actors who seemingly know what they are going to do and how it will benefit them—is not one we usually associate with fish. We have lots of cognitively high-level explanations for our own behavior and find it hard to believe that the same might apply to animals with much smaller brains. But lest one think that the fish are showing a simplified form of cooperation, Bshary’s recent work challenges this notion. Coral trout were presented with a fake moray eel (a plastic model capable of performing a few actions, such as coming out of a tube) that was able to help them catch fish. The setup followed the same logic as the pulling tests in which chimpanzees recruit help when needed, but not if they can complete the task alone. The trout acted in every way similar to the apes and were equally adept at deciding on their need for a partner.
⁵¹

One way to look at this outcome is to say that chimpanzee cooperation may be simpler than we thought, but another is to say that fish may have a better understanding of how cooperation works than we have been willing to assume. Whether all this boils down to associative learning by the fish remains to be seen; if it does, then any kind of fish should be able to develop this behavior. That seems doubtful, and I agree with Bshary that a species’s cognition is tied to its evolutionary history and ecology. Combined with field observations of cooperative hunting between coral trout and moray eels, the experiment suggests a cognition that suits the hunting techniques of both species. Since the trout takes most of the initiatives and decisions, it may all depend on the specialized intelligence of only one species.

These exciting excursions into nonmammals fit the comparative approach that is the hallmark of evolutionary cognition. There is no single form of cognition, and there is no point in ranking cognitions from simple to complex. A species’s cognition is generally as good as what it needs for its survival. Distant species that face similar needs may arrive at similar solutions, as also happened in the domain of Machiavellian power strategies. After my discovery of divide-and-rule tactics in chimpanzees, and Nishida’s confirmation of their use in the wild, we now have a report on ravens.
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It is perhaps no accident that it came from a young Dutchman, Jorg Massen, who spent years with the chimps at Burgers’ Zoo before he set out to follow wild ravens in the Austrian Alps. There he observed many separating interventions in which one bird would interrupt a friendly contact between others, such as mutual preening, either by attacking one of them or by inserting itself between them. The intervener gained no direct benefits (there was no food or mating at stake) but did manage to ruin a bonding session between others. Bonds are important to ravens, because as Massen explains, their status depends on them. High-ranking ravens are generally well bonded, whereas the middle category are loosely bonded, and the lowest birds lack special bonds. Since interventions were mostly carried out by well-bonded birds targeting loosely bonded ones, their main goal may have been to prevent the latter from establishing friendships in order to rise in status.
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This begins to look a lot like chimpanzee politics, which is exactly what one would expect in a large-brained species with a healthy power drive.

Jumbo Politics

We tend to think of elephants as matriarchal, and this is entirely correct. Elephant herds consist of females with young, occasionally followed around by one or two grown bulls eager to mate. The bulls are only hangers-on. It is hard to apply the term
politics
to these herds, since the females are ranked by age, family, and perhaps personality, all of which traits are stable. There isn’t much room for the status competition and the opportunistic making and breaking of alliances that marks political strife. For this, we have to go to the males, also in the elephant.

For the longest time, bull elephants have been viewed as loners who travel up and down the savanna and occasionally get behaviorally transformed by the state of
musth
. Jolted by a twentyfold increase in testosterone, a bull changes into a sort of spinach-eating Popeye, a self-confident jerk ready to fight anyone in his path. Not many animals have such a physiological oddball thrown into their social system. But now we learn from the work by American zoologist Caitlin O’Connell in Estosha National Park, in Namibia, that there is more going on. African elephant bulls are far more sociable than assumed. They may not move in herds like the cows—who stick together to keep predators from bringing down their young—but they know one another individually and have leaders, followers, and semipermanent associations.

In some ways, O’Connell’s descriptions remind me of primate politics, but at other times they sound odd due to the strange ways elephants communicate. For example, a leading bull wary of another may drop his penis during a butt-jiggling retreat. What is going on here? He is awkwardly walking backward while his penis—which is pretty obvious in an elephant—serves as a signal. Why not retract it at such moments? They drop it in submission, or as O’Connell calls it, “supplication.”

On the dominance side as well, their behavior is highly unusual. Here a description of a
musth
display:

He was so agitated that he walked over to the place where Greg had previously defecated and performed a dramatic musth display over the offending pile of feces, dribbling urine and curling his trunk over his head, waving his ears and prancing with his front legs in the air, mouth wide open.
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It used to be thought that the older and larger a bull, the higher-ranking he’d be. If so, this system would be rather inflexible. O’Connell, however, documented status reversals. One leading male gradually lost his ability to rally followers. He would fan his ears and emit a let’s-go rumble, but no one would pay any heed the way they had done in earlier years. His coalition was falling apart, whereas it previously had shown impressive cohesion. One sign of an intact “boys’ club” is that the dominant bull’s vocalizations are echoed by the bulls around him. A subordinate’s call starts at the moment the dominant’s call ends, followed by yet another subordinate, and yet another, resulting in a cascade of repeated calls among the bulls that signal to the rest of the world that they are tight and united.

Elephant coalitions are subtle, and everything these animals do seems a slow-motion movie to the human eye. Sometimes two bulls will deliberately stand right next to each other with ears out, so as to indicate to an opponent that it is time to leave the waterhole. These coalitions dominate the scene, usually arranged around a clear leader. Other bulls come to pay their respect to him, approaching him with outstretched trunk, quivering in trepidation, dipping the tip into his mouth in an act of trust. After performing this tense ritual, the lower-ranking bulls relax as if a burden has been taken off their shoulders. These scenes are reminiscent of how dominant male chimpanzees expect subordinates to crawl in the dust while uttering submissive grunts, not to mention human status rituals, such as kissing the ring of the don, or Saddam Hussein’s insistence that his underlings stick their nose under his armpit. Our species is quite creative when it comes to reinforcement of the hierarchy.

We are familiar enough with these processes to recognize them in other animals. As soon as power is based on alliances rather than individual size or force, the door opens to calculated strategies. Given elephant intelligence in other domains, there is every reason to expect pachyderm society to be as complex as that of other political animals.

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TIME WILL TELL