American Scientist

The Touchstone of Life: Molecular Information, Cell Communication, and the Foundations of Life. Werner R. Loewenstein. 359 pp. Oxford University Press, 1999. $30.

The Touchstone of Life may be the most fascinating book I have read. In it, the world-renowned biophysicist Werner Loewenstein uses the concept of information to explain many of life's intimate processes. Information transfer in and between cells is Loewenstein's entire focus. According to Loewenstein, the amount of information inherent in any given arrangement of matter or energy can be computed from the number of choices we must make to arrive at a particular arrangement among all equally possible ones. The more possible arrangements there are, the more information needed to arrive at any particular arrangement. It is easy to see that by this definition a moderate-sized enzyme or a strand of DNA can contain a lot of information. Information is transmitted from molecule to molecule when the "emitter" molecule makes the atoms of the "receiver" deploy themselves in a corresponding spatial pattern via the electromagnetic force.

Using his information-exchange concept, Loewenstein clearly explains many interesting aspects of life. These include the differences between living and nonliving matter, the "handedness" of biological molecules, the time available for evolution to have occurred, the information capacity of DNA, the apparent relation between introns and organismal "simplicity," codon "wobble," control over reverse transcription of DNA, adaptive mutations and regulation of gene transcription. He even includes a brief section on Isaac Newton's alchemy research.

Occasionally, the author is quite bold. He claims that information loops—hypothetical circles drawn to represent a system in which substance A (for example, RNA) promotes the creation of substance B (protein), which in turn promotes the formation of substance A and so on—"may be in a deep sense the immanent cause of evolution." And Loewenstein implies that man is the superior being on earth, and he affirms the existence of God, both odd in a scientific book. These, however, are off-the-cuff remarks and not focal points.

Loewenstein states that this book was written with both the professional scientist and the layperson in mind, and I think both camps will enjoy it. The language throughout the book is complex like a Tennessee Williams classic yet fast-paced like a Michael Crichton thriller. Main points throughout are italicized for emphasis, making the book easier to follow. I would recommend this wide-ranging book to anyone with an interest in the world and how it got this way. People interested in evolution, cell biology and biophysics will be particularly pleased after reading The Touchstone of Life.—Mark D. Drapeau, Ecology and Evolutionary Biology, University of California, Irvine