Lorenz denied that he had taught his raven to call like this—after all, he had never rewarded him for it. He suspected that Roah must have inferred that since “Roah!” was the call-note Lorenz used for him, it might also work in reverse. This sort of behavior may appear in animals that contact one another vocally and are moreover great imitators. As we shall see, this also holds for dolphins. In the primates, on the other hand, individual identity is usually visually determined. The face is the most characteristic part of the body; hence face recognition is highly developed and has been demonstrated in multiple ways in both monkeys and apes.
It is not just faces that they pay attention to, however. During our studies, we discovered how intimate chimps are with one another’s derrières. In one experiment, they first saw a picture of the behind of one of their group mates followed by two facial pictures. Only one of both faces belonged to the behind, however. Which one would they select on the touchscreen? It was a typical matching-to-sample task of the type invented by Nadia Kohts before the computer age. We found that our apes selected the correct portrait, the one that went with the butt they had seen. They were only successful, though, with chimps that they knew personally. That they failed with pictures of strangers suggests that it was not based on something in the pictures themselves, such as color or size. They must possess a whole-body image of familiar individuals, knowing them so well that they can connect any part of their body with any other part.
In the same way, we are able to locate friends and relatives in a crowd even if we only see their backs. Having published our findings under the suggestive title “Faces and Behinds,” everyone thought it was funny that apes could do this, and we received an IgNobel prize for the study. This parody of the Nobel Prize honors research that “first makes people laugh, and then think.”46
I do hope it makes people think, because individual recognition is the cornerstone of any complex society.47 That animals have this capacity is often underestimated by humans, for whom all members of a given species look alike. Among themselves, however, animals generally have no trouble telling one another apart. Take dolphins, which for us are hard to identify because they all seem to have the same smiley face. Without equipment, we aren’t privy to their main channel of communication, which is underwater sound. Investigators typically follow them around on the surface in a boat, as I did with my former student Ann Weaver, who recognizes about three hundred bottlenose dolphins in the Boca Ciega Bay Intracoastal Waterway estuary, in Florida. Ann carries an enormous photo album with close-ups of every dorsal fin in the area, which she has patrolled for over fifteen years. She visits the bay nearly every day in a small motorboat while on the lookout for surfacing dolphins. The dorsal fin is the body part we see most easily, and each one is shaped slightly differently. Some are tall and sturdy, while others hang to one side or miss a chunk due to fights or shark attacks.
From these identifications, Ann knew that some males form alliances and travel together all the time. They swim synchronously and surface together. The few times that they are not near each other, they get into trouble with rivals, who sense an opportunity. Females and calves, up to the age of five or six, move together, too. Otherwise dolphin society is fission-fusion, meaning that individuals gather in temporary combinations that vary from hour to hour and from day to day. Knowing who is around by looking at a small body part that regularly sticks out of the water is a rather cumbersome technique, however, compared to how dolphins themselves recognize one another.
Dolphins know one another’s calls. This by itself is not so special, since we too recognize each other’s voices, as do many other animals. The morphology of the vocal apparatus (mouth, tongue, vocal cords, lung capacity) varies greatly, which allows us to recognize voices by their pitch, loudness, and timbre. We have no trouble hearing the gender and age of a speaker or singer, but we also recognize individual voices. When I sit in my office and hear colleagues talking around the corner, I don’t need to see them to know who they are.
Dolphins go much further, however. They produce signature whistles, which are high-pitched sounds with a modulation that is unique for each individual. Their structure varies the way ring-tone melodies vary. It is not so much the voice but the melody that marks them. Young dolphins develop personalized whistles in their first year. Females keep the same melody for the rest of their lives, whereas males adjust theirs to those of their closest buddies, so that the calls within a male alliance sound alike.48 Dolphins utter signature whistles especially when they are isolated (lonely ones in captivity do so all the time) but also before aggregating in large groups in the ocean. At such moments, identities are broadcast frequently and widely, which makes sense in a fission-fusion species that dwells in murky water. That whistles are used for individual identification was shown by playing them back through underwater speakers. Dolphins pay more attention to sounds associated with close kin than to those of others. That this is based not on mere voice recognition but on the call’s specific melody was demonstrated by playing back computer-generated sounds that mimicked the melodies: the voice was left out while the melody was preserved. These synthesized calls triggered the same responses as the originals.49
Dolphins have an incredible memory for their friends. The American animal behaviorist Jason Bruck took advantage of the fact that captive dolphins are regularly moved from one place to another for breeding purposes. He played back signature whistles of tank mates that had left long ago. In response to familiar calls, dolphins would become active, approach the speaker, and call in return. Bruck found that dolphins have no trouble recognizing former tank mates regardless of how much or little time they had spent together in the past or how long it had been since they had last seen them. The longest time interval in the study was when a female named Bailey recognized the whistles of Allie, a female she had lived with elsewhere twenty years before.50
Increasingly, experts view signature whistles as names. They are not just identifiers that individuals produce themselves but are sometimes mimicked. For dolphins, addressing specific companions by their own whistles is like calling them by name. While Roah used his own name to call Lorenz, dolphins sometimes mimic the characteristic call of someone else to draw his or her attention. That they do so is obviously hard to prove by observation alone; hence this issue was, again, addressed with playbacks. Working with bottlenose dolphins off the coast of Scotland, near the University of St. Andrews, Stephanie King and Vincent Janik recorded the signature whistles of free-ranging dolphins. They then played the calls back through a submerged speaker while the dolphins who had produced them still swam in the vicinity. The dolphins replied by calling back, sometimes multiple times, to their own characteristic whistles, as if confirming that they’d heard themselves being called.51
The deep irony of animals calling one another by name is, of course, that it was once taboo for scientists to name their animals. When Imanishi and his followers started doing so, they were ridiculed, as was Goodall when she gave her chimps names like David Greybeard and Flo. The complaint was that by using names we were humanizing our subjects. We were supposed to keep our distance and stay objective, and to never forget that only humans have names.
As it turns out, on this issue some animals may have been ahead of us.
9 EVOLUTIONARY COGNITION