A History of the Mind
Evolution and the Birth of Consciousness
by Nicholas Humphrey
Copernicus Books, 1999
Review by Keith S. Harris, Ph.D. on Aug 26th 2003
Despite our most compelling intuitions, perhaps the most truly mysterious thing about consciousness is simply the feeling of mystery we have about it. In this book, Humphreys intends to show us that consciousness is (merely?) a fully-explainable byproduct of the evolution of organisms with complex nervous systems. Consciousness isn't real magic, but rather a particularly good bit of stage magic, natural sleight-of-hand so to speak.
In order to explain this evolutionary conjuring trick, Humphreys distinguishes, at the most basic level, between sensations and perceptions. Sensations are representations of what is happening within the organism and produce feelings, while perceptions are representations of what is happening in the external world and do not themselves (directly) produce feelings.
Consciousness, according to this view, is associated with sensations but not perceptions, and further, the experience of consciousness is simply the expectable result of the evolution of sensation.
Humphrey's thesis, as he recently restated it, may be summarized as follows:
Over evolutionary time, there is a slow but remarkable change. What happens is that the whole sensory activity gets "privatised": the command signals for sensory responses get short-circuited before they reach the body surface, so that instead of reaching all the way out to the site of stimulation they now reach only to points closer and closer in on the incoming sensory nerve, until eventually the whole process becomes closed off from the outside world in an internal loop within the brain.
Humphreys himself, remarking on A History of the Mind, noted that in this book he "took a radically new line about the nature of consciousness, arguing (in contrast to my earlier position) that consciousness is essentially a matter of having bodily sensations rather than of having higher level thoughts -- and I proposed a theory of how consciousness as feeling, as distinct from thinking, may have evolved."
Although such unembarrassed claims would seem likely, at first blush, to disappoint those who have believed consciousness to be truly grand, it should come as no significant shock to readers of Damasio and Dennett, both of whom have also challenged the Cartesian world view.
The central problem many of us will have in accepting an epiphenomenal view of consciousness is the feeling that our consciousness is (almost literally) who we are, and that it exists independently in the universe, distinct from everything that isn't us. Unhappy though it may seem, Humphreys does a very good job of explaining how consciousness could, after all, evolve naturally in, and extend naturally from, complex biological systems (and demonstrates that it is not at all unique to the human species). Consciousness is not, in this view, what we are, but rather what we are produces consciousness. This is not intuitively clear, of course. After all, we are aware of a conscious self (illusory or not) that appears to be the primary agent in our lives, and we would not ascribe this type of awareness to other animals.
Because it broadly straddles the field with its philosophical stance, Humphrey's book, published over a decade ago, still seems quite current. It presents a progressive, stepwise argument for the evolution of consciousness from a fundamental sensation-response form to the incredible rich experience we, as humans, now claim to experience. And while this book may leave the reader wondering how an amoeba's consciousness is then different than our own, the struggle to understand this question can serve as a guide to sort out the differences between consciousness per se, and the consciousness we have of being an individual self.
Humphreys clearly ranks among that exceptional group of scientists who are also philosophers of a literary bent; Dennett has described him as "a great romantic scientist, which sounds like a contradiction in terms, but it isn't."
Having produced at least 84 papers and 9 books, Humphreys is renowned for his literary talent as well, and A History of the Mind is a striking example of his writing ability. Due to the necessary complexity of the material, some sections of the book call for careful re-reading before going forward. And at the end, some readers might wish that he had put the last chapter first, because in it the author so directly recaps and reasonably summarizes the entire course of the reader's journey through the book. Ultimately, however, the journey will be found well worth the effort.
© 2003 Keith Harris Keith Harris, Ph.D., is a clinical psychologist and supervises the research section of the Department of Behavioral Health, San Bernardino County, California. His interests include the empirical basis for psychotherapy research (and its design), human decision-making processes, and the shaping of human nature by evolutionary forces.