The Thinking Man's Cell DennisBrayWetware: A Computer in Every Living Cell2009Yale University PressNew Haven, CT, USA267 pp. $28.00

In the Preface of his book, Bray insists his work is not about single cells possessing consciousness. “I say repeatedly in the book as clearly as English words will allow that in my opinion single cells are not sentient or aware in the same way that we are,” he writes (p. ix). The key part of this claim, however, is the clause “in the same way that we are.” Bray is not equating cellular and human cognition. However, he is up to something profound and perhaps slightly sneaky. Rather than place consciousness on a pedestal that only humans can reach, Bray seeks to define it along a continuum of systems and states. In this view, consciousness is not an absolute, and by some definition cells can indeed be said to be aware of themselves and of their surroundings. To explore these ideas, the book swiftly covers most of the important work to-date in the nascent field known as systems biology. It provides an excellent introduction to the field that is broadly accessible and would do well as required reading for graduate students in the biological sciences. Bray gives a colorful tour of diverse topics encompassing microand molecular biology, artificial intelligence, neuroscience, biochemistry, and robotics. In another context these subjects might have had less to do with one another—here, Bray convincingly shows how they are parallel fields in search of a central theory of cognition. His skill is in framing the basics of molecular systems biology by way of deep and thought-provoking questions: What is the basis for consciousness? To what extent are machines and cells really intelligent? Single cells can exhibit extraordinarily complex behaviors. To respond to their environment, single-celled organisms such as the amoeba adopt a complex set of internal cell states that Bray likens to feelings of hunger, curiosity, and fatigue (Chapter 1). He points out that these very complicated behaviors make