Chimps once again triumph. Tetsuro Matsuzawa, a researcher at Kyoto University, showed that a chimpanzee named Ayumu clearly out-performed humans on some working memory tests, a category of short-term recall. What is surprising is that anybody finds this surprising. We continue to be blinded by our hubris and conceit, so sure are we that human beings are better and above all other animals. As Ayumu shows, we will continue to be disappointed. Let's take a look at the score board.
Intelligence
Without a doubt, human beings possess a level of intelligence, self-consciousness and self-awareness greater by degree than is found in any other animal. Evidence suggests that no animal besides the human kind is aware of its own mortality, the ultimate expression of self-awareness. (Elephants might be an exception). Only humans bury their dead ceremonially. Chimpanzees do not visit their lawyers to make out a will in anticipation of impending death. For centuries, philosophers have taken this highly developed sense of self in humans to mean that intelligence does not exist at all in other animals. Descartes was convinced that animals completely lacked minds, and his influence is felt even today. Even Stephen Jay Gould, no species-centric chauvinist, concluded that consciousness has been "vouchsafed only to our species in the history of life on earth."
With all due respect to the late Professor Gould, perhaps one of the greatest evolutionary biologists of our time, and to Descartes, the issue is not so simple. As with almost all aspects of comparative biology, intelligence, self-consciousness and self-awareness are elements of a continuum, rather than phenomena with sharp boundaries between species. Intelligence and self-awareness do not belong exclusively in the domain of humankind.
A rough hierarchy exits among the concepts of "intelligent," "self-conscious," and "self-aware." One must be intelligent to be self-conscious, and in turn, self-conscious to be self-aware. So let's begin with intelligence, the first ingredient in the recipe for self-awareness, in order to explore how these "human" capabilities are distributed throughout the animal kingdom.
Intelligence can be thought of as the ability to learn from experience (acquire and retain new knowledge), and to subsequently apply that new knowledge with flexibility to manipulate or adapt to a changing environment. Or intelligence can be seen as the ability to create abstract thought, beyond instinct or responses to sensory input.
The primary difficulty in defining and measuring intelligence precisely is that mental acuity is situationally dependent. While dolphins are clearly smart you would be severely challenged to teach one to climb a tree. An animal's intelligence, or more precisely, its ability to manifest its intelligence, is tightly correlated with its natural environment, and its evolutionary adaptations.
Intelligence, no matter how we define the concept, is not an all-or-nothing phenomenon. Animals have diverse adaptations that define the context of intelligence, making interspecies comparisons almost meaningless. Intelligence is found by degrees across the animal kingdom, and not in some nice neat linear correlation with some other trait like the development of mammary glands. Being smart seems to be a trait unique to human beings only when we artificially designate our particular suite of characteristics as the definition of intelligence, proving that circular logic is not too intelligent.
All of the references given here are cited in an extensive bibliography of Beyond Cosmic Dice: Moral Life in a Random World.
Self-consciousness
For most of human history, people were convinced that no animal could be self-conscious, with Descartes representing the poster child of this viewpoint. Our ability to be conscious of our own existence was seen to endow humans with something special. Self-consciousness was considered the ultimate expression of humanness. That is until we learned more about our animal cousins. Some animals indeed exhibit this most "human" of traits; in fact, self-consciousness is probably widespread in the animal kingdom.
The idea of self-consciousness is not without controversy; the scientific community is not unified in defining the concept. For example, some scientists use the term "self-conscious" in the sense that others use the term "self-aware" (as I do here): an animal's thought about thought, in which an animal has a "second order representation" of his own mental state. That means an animal not only thinks, but also thinks about thinking. Some scientists call the ability to "think about thinking" self-consciousness, and others call it self-awareness. This academic parsing is why cocktail parties at a professor's house can be so stimulating.
But the two concepts of awareness and consciousness are quite distinct, and should not be confused one with the other. Self-awareness represents a further refinement of self-consciousness. A simple definition of self-consciousness can be distilled to: understanding that you as an individual are distinct from the external environment, and at the same time recognizing that others are similarly aware of you as an individual. I can only recognize Ralph as a unique person if I first understand that I too am an individual. With this meaning then, the ability to recognize other individuals is perhaps the most important indication of an animal being self-conscious. The notion of self-consciousness is therefore amenable to experimental investigation because we can test for individual recognition. We have a window into the mind!
In the animal kingdom, individual recognition, and therefore self-consciousness, would most readily be found in highly social animals where survival depends on recognizing dominant individuals, and in turn, dominating those lower in the social hierarchy. (Remember high school)? Animals that pair-bond for life, and therefore can recognize a mate among many conspecifics, are also more likely to be self-conscious, at least by the definition given here.
For sticklers of logic, one implication here is that an animal can be self-conscious without being self-aware. That is, an animal can recognize itself as an individual among other individuals, without knowing anything deeper about its own mental state. But at the same time, gregarious animals would also have evolutionary pressures to recognize not only the dominant animal in the group as an individual, but also his emotional state and that of others in the hierarchy. You might get more food if you know when to approach a kill when the big guy is in a good mood. So while it is possible to be self-conscious without being self-aware, the development of one trait might typically lead to the other.
Self-awareness
Self-awareness is a further refinement of the concept of self-consciousness (while some scientists invert this relationship), in that you not only recognize yourself as an individual relative to others and the physical environment, you are also aware of your own mental state, including your own internal thoughts independent of the external world. Your thoughts are unavailable to anybody but you until you decide to expose them to the external world either through behavior or some type of communication. Self-awareness depends on no other creature but you. You would be self-aware even if you were the last person on earth, with no other sentient being to recognize your presence. Self-awareness is your brain acknowledging its own existence.
Place a chimpanzee, let's call him Alessandro, in a room in which he finds a large mirror. After a brief period in which Alessandro has become familiar with the room and the mirror, anesthetize him. While he is asleep, paint a dot of yellow paint on Alessandro's forehead, and gently place him back in the room. After waking up, most animals will not notice or react to the dot, continuing to treat the reflection in the mirror as another animal. But Alessandro, and his fellow chimpanzees and orangutans, will recognize the image in the mirror as themselves, touching their foreheads and examining the dot. That demonstrates that Alessandro knows the forehead in the mirror is his, and that he normally does not have a dot on his head.
One could object that this experiment in fact only demonstrates self-consciousness, rather than self-awareness, proving that Alessandro recognizes himself as an individual. This is a gray area. We cannot state with certainty from this particular experiment if Alessandro is aware of his own mental state even if the results hint in that direction. Nevertheless, we have from this and other observations at least an indication that primates like Alessandro might be truly self-aware. We also have evidence that mammals other than primates share this talent with humans. Using a modified version of the dot-on-the-forehead procedure, mirror self-recognition has been demonstrated in bottlenose dolphins, magpies and elephants.
Dolphins and porpoises have also demonstrated originality and creativity, both tangential indicators of self-awareness. An animal can only be creative in context of understanding its own behavior and intent, something that requires a level of self-awareness. Likewise, the act of creating something new, the capacity for originality, usually requires a deep understanding of one's own internal representation of the world as it now exits, also a feature of self-awareness. Animals that clearly demonstrate originality and creativity are likely self-aware, at least to some degree.
At the Makapuu Oceanic Center in Hawaii, trainers working with a female rough-toothed dolphin named Malia praised or fed her fish only for behaviors that had not been previously rewarded. Within a few days, Malia began performing novel aerial flips, corkscrews, new tail flaps, new twisted breaches, and other never-before-seen behaviors. Malia learned early on that the trainers were looking for new acts, not repetitions of previously demonstrated talents. As her repertoire expanded, she needed to create ever more unique combinations of movements to get a reward, which she did with aplomb, performing stunts so unusual that trainers could not have otherwise encouraged the behavior through standard training techniques. This propensity for originality and creativity (signs of self-awareness) was not a fluke unique to one individual.
Intelligence, self-consciousness and self-awareness would not seem to be uniquely human. Ayumu is not impressed.
Of course humans are unique, as are all species by definition. But nothing about our biology or evolutionary history makes us special. We remain a short-lived biological experiment with too little time to know if having a big brain is adaptive. Sure we have complex language and mathematics, but we also have weapons of mass destruction and the ability to destroy the resources that sustain us. The jury is out. We should be a bit humble about our position in the biosphere.