The Ancient Origins of Consciousness, by Todd Feinberg and Jon Mallatt, published by MIT Press, addresses the question of the rise of consciousness in living organisms from three different viewpoints: the philosophical, the neurobiological and the neuroevolutionary domains.
From a philosophical standpoint, the question is whether consciousness, i.e., subjective experience, can even be explained by an objective scientific theory. The so-called “hard problem” of consciousness, in the words of David Chalmers, may forever remain outside the realm of science, since we may never know how physical mechanisms in the brain create the subjective experience that gives rises to consciousness. The authors disagree with this pessimistic assessment by Chalmers, and argue that there is biological and evolutionary evidence that consciousness can be studied objectively. This evidence is the one they propose to present in this book.
Despite the argument that the book follows a three-pronged approach, it is most interesting when describing and analyzing the evolutionary history of the neurological mechanisms that ended up created consciousness in humans and, presumably, in other mammals. Starting at the very beginning, with the Cambrian explosion, 540 million years ago, animals may have exhibited some kind of conscious experience, the authors argue. The first vertebrates, which appeared during this period, already exhibited some distinctive anatomic telltales of conscious experiences.
Outside the vertebrates, the question is even more complex, but the authors point to evidence that some arthropods and cephalopods may also exhibit behaviors that signal consciousness (a point poignantly made in another recent book, Other Minds and Alien Intelligences).
Overall, one is left convinced that consciousness can be studied scientifically and that there is significant evidence that graded versions of it have been present for hundreds of millions of years in our distant ancestors and long-removed cousins.