by Diana Reiss
We really didn't believe data from another dolphin was necessary, and we wrote a long letter explaining why. We also outlined the modifications we were willing to make in response to the first three referees' helpful comments and pointed out what we saw as the unambiguous factual errors of the fourth referee. To no avail. Our only way forward, it was made very clear, was to collect data on Tab and combine them with those from Presley. Why hadn't we done that in the first place? By this time, we were extremely stressed, having ridden the wave of exhilaration with our results, the devastation of initial rejection, optimism that our reasoned pleas would prevail, then rejection again.
In the midst of all this Gordon Gallup called me and said, "Congratulations on getting your paper into Nature, Diana." He had been one of the first three reviewers and he'd assumed that, armed with his very positive assessment, the paper would sail through. He was astonished when I said, "Well, actually, Gordon, it was rejected." He was very supportive and urged us to persevere. This was the scientist who'd developed the test we'd successfully put Presley through, and yet here Lori and I were, still knocking on Nature's door.
We were able to collect the data we needed with Tab extremely quickly, for two reasons. First, we already had baseline data on him, in the form of a video record of his behaviors in the presence and absence of a mirror. And we had early sham-marking data on him too. Second, our experience with the mark test with Presley and our subsequent analysis allowed us to streamline our protocol. We knew what we were doing, and we were able to do it expeditiously. Less than a dozen actual mark tests and a handful of sham-mark tests gave us what we required. Tab's behavior was pretty much a carbon copy of Presley's, and we kicked ourselves more than a little for having thought that his possibly defective sight might interfere with his visual discrimination ability. Tab showed the same urgent motivation to get to the second, smaller, pool after being marked, and once there, he was just as diligent in examining the marked areas. There was no question, in our estimation, that Tab had the operational definition of mirror self-recognition.
We redrafted the paper and sent it back to Nature in the late summer with every expectation and hope that this time it would be accepted. After all, we had done what had been asked of us. Yet the paper was rejected again. The editor had sent it to the same four referees, and the fourth referee was even more strident in condemning the manuscript, essentially saying, I don't ever want to see this manuscript again. We were deflated once more.
There was nothing more to be done with Nature, and so we said, "Okay, let's try Science." Science, based in Washington, D.C., is in many ways the American counterpart to Nature, and there is something of a professional rivalry between them. Like Nature, Science publishes groundbreaking papers across the spectrum of scientific disciplines, but the editors at Science are, if anything, even more conservative than those at Nature. Our manuscript bounced back to us from the editorial office of Science as if it had been attached by an elastic band, superfast. A curt rejection letter explained that the subject matter was deemed to be of insufficient general interest. We were advised to submit it to a more specialized journal.
This time we were not only disappointed but also astonished. Our experience over the years with dolphin research was that the public couldn't get enough information about dolphin behavior. Rather than go down the more-specialized-journal route, we chose PNAS, the Proceedings of the National Academy of Sciences. An inside joke in scientific circles is that PNAS also stands for "Post Nature and Science." Proceedings is the house journal of the National Academy of Sciences, the most prestigious scientific institution in the United States. To have a manuscript accepted for publication in PNAS, authors must find a member of the academy who is willing to "communicate" the manuscript to the journal's editors. (Election to the academy is a much-coveted recognition that one has established great authority in one's particular field.) Like Nature and Science, PNAS publishes papers across a very broad spectrum of scientific disciplines, but these papers tend to be much more recondite than those of the other journals, not typically the topics of dinner-table conversation except among a small number of specialists around the world.
Lori and I discussed whom we might approach, and we quickly decided on Donald Griffin, the father of the study of animal cognition. I knew Don well, so I called him. He asked me to send him the manuscript and said he was excited about the results and would be happy to communicate it to PNAS and serve as the editor. The manuscript arrived at the Proceedings' offices on October 3, 2000, and was sent out for review. This time there was no negative third, or fourth, referee, and the paper was accepted; it was published on May 8, 2001. "These findings ... offer the first convincing evidence that a nonprimate species, the bottlenose dolphin, is capable of [mirror self-recognition],"1 we wrote. We also said that "research on self-recognition in other species will have profound implications for the idea that humans are the only species to conceive of their own identity."2
Lori and I were immediately swamped with requests for television, radio, and print-media interviews. Despite the incredulity of some reporters, who found it hard to believe that what we were describing could possibly be true, the media as a whole seemed entranced with the notion that bottlenose dolphins were "geniuses of the sea," as a reporter for the New York Times put it. The Wildlife Conservation Society (the parent of the New York Aquarium) has a press office that tracks media coverage of its scientists' work. I was astonished, and excited, when I got a memo from the office saying that we had had more than nine hundred media hits in the first week. It was by far the highest figure they had ever seen.
The story appeared on every major television channel in the country, and in every newspaper and newsmagazine. There was a spoof on Saturday Night Live in which the host asked what the difference was between a particular American pop star and dolphins. The answer: Dolphins are intelligent enough to recognize themselves in the mirror. On The Daily Show, Jon Stewart showed a photograph of me and said something like "Dolphins at the New York Aquarium are so smart that they recognize themselves in mirrors. Dolphin researchers aren't changing into their wetsuits in front of them anymore." Trivial Pursuit added a new question to the game: Which animal recently showed self-awareness?
My one regret about the PNAS paper is that we weren't able to include something Presley did twice, something that Lori and I thought was further corroborative evidence for MSR in the dolphins and something that people subsequently were curious about. "Did the dolphins ever try to rub off the mark after they'd seen it?" my scientific colleagues and other people often asked me. On two occasions after Presley was marked, he raced to the mirror, saw the mark, and then went to the side of the pool and rubbed the area of the mark against the pool wall. He then returned to the mirror, examined the location again, and seemed to be satisfied that he had achieved his goal. We had included this account in the first draft of the paper, but the paper was too long and we'd had to cut it.
This was especially unfortunate because a few months after the PNAS paper was published, a short item appeared in Scientific American entitled "The Flipper Effect." The Flipper effect, explained the small piece, was "the urge to believe that creatures as intelligent and engaging as dolphins must also be self-aware and empathetic." Primatologist Daniel Povinelli noted that dolphins didn't have hands with which to touch marks on their bodies but if they actively tried to rub off such marks, he would consider that evidence of self-awareness.3 Until such time as this was observed, however, he would remain unconvinced.
Nonetheless, we felt we had achieved our goal of meeting the rigorous standard that Gordon Gallup had set three decades earlier with his chimp work. Dolphins had shown themselves to be capable of self-recognition and this level of self-awareness. They have consciousness, just as chimps and people do. When I think about how difficult it was to establish this, what comes to mind is Bob Thaves's quote about Ginger Rogers: "Sure [Fred Astaire] was great, but don't forget, Ginger Rogers did everything he did backward
s ... and in high heels!" Well, Presley and Tab had done everything that Gordon's chimps had done.
And with no hands!
7. Cognitive Cousins
DAAN, A MATURE MALE bottlenose dolphin, shared a very large pool for many years with several other dolphins and a mature male Cape fur seal in an oceanarium in Humewood, South Africa. Daan was an inquisitive individual, as dolphins usually are, and he became particularly interested in the divers that from time to time entered the pool to remove algae from the inside of the glass viewing ports. He spent long periods patiently watching the divers as they scraped, scraped, scraped at the film of algae on the glass. Very soon, Daan took it into his mind to help out. He found a seagull feather, held it in his mouth, and proceeded to clean the window just as he had seen the divers do.
When a diver did the cleaning, he steadied himself by holding on to the frame of the viewing port with one hand, and he used the other to clean the glass with broad strokes of a brush. Daan adopted the whole posture. He kept constant contact with the frame using one flipper, and he used the feather to clean the glass with the same broad strokes he'd seen the divers use. And he hadn't just watched the divers; he'd also listened to them. As he cleaned the windows he emitted "sounds almost identical to that of the diver's air-demand valve" and he released "a stream of bubbles from the blowhole in a manner similar to that of exhaust escaping from the diving apparatus."1 Daan was apparently so enamored with his "job" that for almost two months he refused to allow any diver near the window, and at night he rested above it rather than in the center of the pool, which had been his previous nocturnal spot.
Mimicry of this sophistication requires a good deal of intelligence. And dolphins don't have to be mature to display such inventiveness. Dolly was a six-month-old bottlenose dolphin in Daan's pool. She loved the attention of the observers who were scoring dolphin behavior in an underwater viewing chamber. Dolly developed the habit of offering the observers objects, such as feathers, stones, seaweed, and fish skins, pressing them against the glass as tokens of the relationship she seemed to want to establish. When the observers ignored Dolly, she would rapidly bring three or four objects in quick succession. Dolly's endearing behavior was hard to ignore.
One day, one of the observers was smoking a cigarette and happened to let out a large plume of smoke. Dolly apparently noticed it, and without hesitation she swam to her mother, briefly suckled, returned to the window where the observer was watching, and let out a mouthful of milk that "engulfed her head, giving much the same effect as had the cigarette smoke."2 The observer reported that he was "absolutely astonished," and he must have displayed his feelings, because on several subsequent occasions, Dolly used this little improvised display to attract attention.
Had Dolly occasionally "spilled" milk while suckling and remembered what it looked like? Perhaps, though I'm sure it doesn't happen often, to judge from my observations of mothers and calves. Had Dolly made the connection between the visual appearance of the cloud of smoke and the cloud of spilled milk and then used that recognition in a completely novel way? Imitation is one of the highest forms of social learning, and it requires selective attention and considerable intelligence. Dolphins are extremely good at it, even better than chimpanzees. This display of intelligence prompted primatologist Andrew Whiten to observe that dolphins "ape better than apes."3
These two stories are wonderful examples of dolphins actively observing us while we're observing them. I know from experience that you don't have to be around dolphins for very long before you become keenly aware that you are an object of dolphin scrutiny and that there's a palpable intelligence behind it. These anecdotes were both reported by a trained observer, the aquarium curator, who was familiar and knowledgeable about the behavioral history of the dolphins. Anecdotal reports by trained observers when compiled and viewed as a whole can give us important glimpses and insights into the minds of other species and can inform new directions of scientific investigation into those species' cognitive realms. The anecdotes don't generally get published in scientific journals, but they are telling nonetheless.
The questions generally asked are: Just how intelligent are dolphins? Are they almost as smart as humans? Are they smarter than chimpanzees? Yet the question of who is more or less intelligent is perhaps the wrong one to ask. As a young graduate student I found Ross Ashby's definition of intelligence very helpful. Ashby, a cybernetician, studied complex systems and defined intelligence as the "power of appropriate selection," be it in man, animal, or machine. Ashby's definition levels the playing field and allows intelligence to be considered relative to the sensory abilities and social and environmental factors at work. He proposed that
"problem solving" is largely, perhaps entirely, a matter of appropriate selection. Take, for instance, any popular book of problems and puzzles. Almost every one can be reduced to the form: out of a certain set, indicate one element ... It is also clear that many of the tests used for measuring "intelligence" are scored essentially according to the candidate's power of appropriate selection ... Thus it is not impossible that what is commonly referred to as "intellectual power" may be equivalent to "the power of appropriate selection." Indeed, if a talking Black Box were to show high power of appropriate selection in such matters—so that, when given difficult problems, it persistently gave correct answers—we could hardly deny that it was showing the "behavioral" equivalent of "high intelligence."4
Dolphins are very clever at locating and capturing schools of fish. Humans do the same thing by cleverly designing and using boats and nets. Every intelligent species (and others that are less well endowed mentally) will, because of its unique evolutionary history, possess special abilities unmatched by other similarly intelligent species. As the University of Wisconsin psychologist Charles Snowdon put it, "Specializations do not make one species ‘smarter' than another, but they do make for uniquely sculpted minds."5 Finding the answer to the question, Who is smarter than whom? is therefore not always helpful, or even possible. When we ask that kind of question, we inevitably think about the issue in very human-centered terms, based on our notion of intelligence.
Dolphins are a large-brained, highly gregarious species whose body form and sensory systems have been exquisitely shaped for life in the seas by millions of years of evolutionary selection. Working with them has presented me with a gnawing concern: Would we recognize their form of intelligence, the meaning of their messages, even if it were right there in front of us? These nonprimates, so alien in body form, from so foreign an environment—how do we search for meaning in their behavior and communication? What may be meaningful to dolphins, so important to them in complex sea-based social networks, may be so alien to us that we can't even conceive of it.
Ludwig Wittgenstein famously said, "If a lion could talk, we wouldn't be able to understand it." Wittgenstein's point was that even if the lion could speak perfectly good English, its experience of the world is so different, so alien, compared to ours that what the lion would have to say would make little sense to us.
To some degree, there is the same conundrum when we think about another species' intelligence. We have to ask ourselves whether we would even recognize an intelligence in another species that is radically different from ours. Douglas Adams nicely captured the essence of the problem in The Hitchhiker's Guide to the Galaxy:
"It is an important and popular fact that things are not always what they seem. For instance, on the planet Earth, man had always assumed that he was more intelligent than dolphins because he had achieved so much—the wheel, New York, wars and so on—whilst all the dolphins had ever done was muck about in the water having a good time. But conversely, the dolphins had always believed that they were far more intelligent than man—for precisely the same reasons."6
It is clear that dolphins are among the smartest creatures on Earth. So what do we know about dolphin minds compared to other minds? What parallels do we see with other intelligent species? What insights can we glean from these o
bservations about the nature of intelligence and other high-level cognitive functions, such as self-awareness? I know dolphins are intelligent based on what I've seen and experienced with them over more than three decades. The question is: How do we characterize their kind of intelligence? In other words, what is it like in the mind of a dolphin?
Let's start with something a bit more concrete. Let's talk about brains. Humans, in contemplating our place in nature, have long been obsessed with our species' big brain. We named ourselves Homo sapiens, "wise man" or "knowing man," in recognition of the powers with which it endows us. The human brain is held to be superior relative to other species' due to its larger-than-expected size and its enlarged, well-developed cerebral cortex. Brain size has been linked to intelligence because in mammals and birds, those species with the largest brains show the greatest range and versatility in behavior.7 Dolphins and other toothed whales also boast big brains, significantly larger than our own. The bottlenose dolphin—Pan and Delphi's species—has a brain that weighs about seventeen hundred grams; the human brain weighs about thirteen hundred grams, so the dolphin brain is about 30 percent larger. Much of the dolphin's brain weight is made up of cerebral cortex—considered to be the seat of higher cognitive functions.
If you are developing something of an inferiority complex, you might comfort yourself with a measurement called the encephalization quotient, or EQ.8 This measure takes into account the size of one's body relative to the size of one's brain. EQ represents the ratio of brain weight to the average body weight for a given species. Among mammals, for example, Homo sapiens has an EQ of 7.0, which means that the human brain is seven times larger than expected for the human body size. Our closest biological relatives, the great apes, possess brains that are also larger than expected, a bit more than twice as large, but they are relatively smaller brains by this measure: the EQ for chimpanzees is 2.3; for orangutans, 1.8; for gorillas, 1.6. Elephants and whales also have larger brains than expected, and they show a ratio similar to that of the great apes: more than twice the expected size. Most other animals have smaller brain-to-body ratios than humans and great apes. With one exception—the dolphin. Dolphin brains are approximately 4.2 times larger than expected for their body size—the highest ratio of any species other than humans, making them easily the second most cerebrally endowed species on the planet, way ahead of the great apes.
