Are animals conscious? This question has a long and venerable history. Charles Darwin asked it when pondering the evolution of consciousness. His ideas about evolutionary continuity - that differences between species are differences in degree rather than kind - lead to a firm conclusion that if we have something, "they" (other animals) have it too.

In July of this year, the question was discussed in detail by a group of scientists gathered at the University of Cambridge for the first annual Francis Crick Memorial Conference. Crick, co-discoverer of DNA, spent the latter part of his career studying consciousness and in 1994 published a book about it, The Astonishing Hypothesis: The scientific search for the soul.

The upshot of the meeting was the Cambridge Declaration on Consciousness, which was publicly proclaimed by three eminent neuroscientists, David Edelman of the Neurosciences Institute in La Jolla, California, Philip Low of Stanford University and Christof Koch of the California Institute of Technology.

The declaration concludes 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."

My first take on the declaration was incredulity. Did we really need this statement of the obvious? Many renowned researchers reached the same conclusion years ago.

The declaration also contains some omissions. All but one of the signatories are lab researchers; the declaration would have benefited from perspectives from researchers who have done long-term studies of wild animals, including nonhuman primates, social carnivores, cetaceans, rodents and birds.