Almost everyone has had a passing experience—perhaps one of looking into the eyes of a chimpanzee in a zoo or of settling down beside the family dog in front of a fire in the fireplace on a cold day—where it seemed intuitively clear that the animal had an intelligence and emotions of some sort or even a coherent consciousness not radically different from human consciousness. Of course, those ideas could be wrong, and certainly, when considered as mere intuitions or the product of a simple, anecdotally-recalled event, they remain in a different realm from scientific understanding. Indeed, only a generation or two ago no reputable scientist would even entertain the notion of animal consciousness–at least not professionally. Such was the ruling paradigm, accepted by both common and scientific presumption. Humans are conscious beings. Animals are not.
This conceptual divide between human and nonhuman has deep roots reaching back at least to the time of Enlightenment philosopher René Descartes, who famously asserted that humans are separated from all other living creatures by an un-crossable chasm. Humans possess “reason,” he wrote, whereas animals do not. Perhaps animals might experience some kind of sensation, but if so, the absence of reason renders those sensations meaningless. As the philosopher wrote in his Discourse on Method (1637), animals possess “no reason at all,” and therefore nature “acts in them according to the disposition of their organs, just as a clock, which is only composed of wheels and weights, is able to tell the hours and measure the time.” Unreasoning and unconscious, then, animals are merely a naturally-occurring sort of machine.
The Cartesian divide was tested by the eighteenth-century Swedish taxonomist Carolus Linnaeus, who, having identified a vast network of anatomical continuity among all living things, described humans as one species among many in the primate group: a group sharing in common such features as grasping hands, strong binocular vision, and large brains.
And then, with his 1859 publication of On the Origin of Species, Charles Darwin challenged Descartes’ radical discontinuity more directly and emphatically. Darwin argued that the unmistakable tree of anatomical similarities Linneaeus had identified among species was actually a picture of familial relationships; and with his theory of evolution by natural selection, Darwin convincingly explained how such an astonishing family tree could develop over extended time. Darwin’s concept of evolution by natural selection would be accepted by most biologically-oriented scientists during Darwin’s lifetime, and it was clearly the best explanation for anatomical continuity among species. It would take more than a century, however, before Darwin’s understanding (see: The Descent of Man, 1871, and The Expression of the Emotions in Man and Animals, 1872) of the logical sequel to anatomical continuity–that is, neurological, behavioral, psychological, and mental continuity–would be considered with a comparable interest. At least four important events have happened since the middle of the twentieth century to expand the scientific receptiveness to such ideas.
The first was an explosion in the numbers and quality of large mammal observations in the field. The origins of this explosion may have had to do with such practical events as the introduction of effective anti-malarial drugs and low-cost jet travel to the tropics, perhaps as well the postwar prosperity in the United States, along with a certain refocusing of scholarly disciplines. In any event, starting mostly in the late 1950s and gaining impetus during the 1960s, large numbers of field scientists—including those trained in “animal sociology” in Japan, in zoology and anthropology in the United States, and in ethology in Europe—began watching large mammals in their natural habitats. The anthropologists were particularly interested in apes, since they are closest to humans and (so the recently-hatched practitioners of the new physical anthropology believed) might provide insights into the lives and behaviors of the not-so-distant ancestors those primates share in common with humans. 
The ethologists from Europe were products of a long tradition (begun by Oskar Heinroth in the early twentieth century, distinguished by the Nobel Prize given to Karl von Frisch, Konrad Lorenz, and Nikolaas Tinbergen in 1974) that had already done some superb work on insects and birds in Europe, but had in the process become, perhaps, overly attached to the idea of instinct as the central element underlying most animal behavior. By the 1960s and 1970s, hundreds of trained scientists and their assistants had watched or were watching large and large-brained mammals in dozens of places, many of them in Africa where elephants can be found and where three of the four great apes live. One effect of this sudden explosion in scientific observations was the emergence of an increasingly generous sense of some animals as deliberative creatures.
The second event was a creative expansion in the nature of experimental studies on animals. This expansion included language-acquisition studies beginning with the successful attempt to teach sign language to a chimpanzee named Washoe (from 1967 on), followed by sign-language work at several institutions on all four ape species, and from there branching out in some surprising directions such as the spoken-language work Irene Pepperberg has done with African gray parrots. The creative expansion also included the mirror studies, which, starting with Gordon Gallup’s original work on chimpanzees in 1970, have altogether shown that certain large-brained mammals (all the apes, as well as elephants, dolphins, and magpies [a corvid]) will spontaneously learn to recognize themselves as individuals in a mirror reflection. Gallup described this as evidence of self-consciousness.
Then came the publication of two influential books by Donald Griffin: The Question of Animal Awareness (1976) and Animal Thinking (1985). Griffin had earned his reputation as a brilliant experimental zoologist by discovering and documenting that bats navigate by echolocation. He founded the discipline of cognitive ethology, and his two early books combined rigorous and compelling argument with an almost encyclopedic array of references to animal behaviors that showed evidence for thinking, planning, awareness, and creative problem-solving.
The fourth event is emerging in contemporary time. That is the application of modern technologies and techniques of neuroscience to the comparative study of human and non-human animal brains. These comparative studies have begun reinforcing the concept Darwin always maintained: that continuity among related species will inevitably extend to the cognitive. To recall the language of the 2012 Cambridge Declaration on Consciousness (written by Philip Low, edited by Jaak Panksepp, Diana Reiss, David Edelman, Bruno Van Swinderen, and Christof Koch): “Convergent evidence indicates that non-human animals have the neuroanatomical, neurochemical, and neurophysiological substrates of conscious states along with the capacity to exhibit intentional behaviors. 
Consequently, the weight of evidence indicates that humans are not unique in possessing the neurological substrates that generate consciousness. Non-human animals, including all mammals and birds, and many other creatures, including octopuses, also possess these neurological substrates.”
Koch (2012) summarizes the problem of thinking about human consciousness this way: “On the one hand is the brain, the most complex object in the known universe, a material thing subject to the laws of physics. On the other hand is the world of awareness, of the sights and sounds of life, of fear and anger, of lust, love, and ennui…how does the brain construct conscious experience?” He proposes one theoretical possibility. Some researchers propose others (see point-counterpoint, Cohen et al., 2012a,b; Tsuchiya et al. 2012). No one has a definitive answer to what Chalmers (1995) calls the “Hard Problem.”
If controversy exists about human consciousness, what can be said about nonhuman consciousness? Given that comparative psychologists, neuroethologists, and cognitive ethologists are still trying to determine both the similarities and differences among human and nonhuman brains, and the extent to which humans and nonhumans experience the world in both similar and different ways, what can we know about nonhuman states of consciousness? A discussion at the Francis Crick Memorial Conference in Cambridge (UK), tried to address those complex questions and concerns, as did another 2012 meeting (Boly et al., 2013). We hope to expand these earlier conversations to the larger Harvard community.
But our primary goal for this symposium is to create a conversation among experts from three areas of scholarship—neuroscience, animal behavior science, and the humanities—on the subject of animal consciousness.
We wish to explore the evidence, based largely on work in neuroscience and animal behavior science, for a clear evolutionary continuum, among mammals and other taxa, of a human-like consciousness. To the degree that the evidence supports such things to be true, then one can say that we Homo sapiens live on this planet as one form of consciousness among many. While the notion may not be startling to many, it implies more generally, as humanists are likely to suggest and develop, that we are on the verge of establishing a new cultural consensus about the nature of animals. Such consensus should have major ethical and legal implications.
In order to facilitate this cross-disciplinary conversation, seminar participants will be asked to address their talks to an imagined audience outside their field. Among other things, this means that participants should speak and write in the first person, where appropriate, and will use language that can be immediately grasped by anyone. Where technical language or descriptions seem unavoidable, the participants will be encouraged to define and explain clearly what they mean.
The Harvard Animal Consciousness Symposium 