Life Everywhere: The Maverick Science of Astrobiology (review)

Life Everywhere: The Maverick Science of Astrobiology. By David Darling. New York: Basic Books, 2001. Pp. xiii + 206. $26.

In the past two years, two new books have addressed the question of whether complex life is common in the universe. In Rare Earth, Peter Ward and Don Brownlee (2000) took a pessimistic stance. In their view, life itself is commonplace, but multicellular animal life is rare because its evolution depended on a variety of factors--a large moon to stabilize the tilt of Earth's spin axis, a giant Jupiter to shield us from comets, plate tectonics to recycle carbon dioxide and help stabilize climate--that would be difficult to duplicate on another planet in another planetary system (Kasting 2001). David Darling's book, Life Everywhere: The Maverick Science of Astrobiology, is a timely response to this thesis. As the title suggests, Darling argues that life is a universal phenomenon and that Earth is only one of a multitude of worlds on which it originated and evolved. Furthermore, the trend toward complexity, ultimately leading to animals and even intelligence, is a built-in attribute of the life process. So, SETI (Search for Extraterrestrial Intelligence) enthusiasts now have something to trot out when detractors suggest that they are wasting their time (but not taxpayers' money, as SETI has been privately funded since the mid-1980s).

Darling's book does more, though, than simply counter the "rare Earth" hypothesis. The author explores the entire "new" science of astrobiology: the search for life beyond Earth. I have put "new" in quotation marks here because NASA has been funding research in this area for at least 25 years under the rubric of "exobiology," and because Carl Sagan was writing books on it even earlier than that. Indeed, it was one of Sagan's first books, Intelligent Life in the Universe (Shklovskii and Sagan 1966), that piqued my own interest in this topic when I was a college student. But the interest in looking for extraterrestrial life has increased dramatically over the past four or five years as a result of new discoveries: the identification in 1996 of a Martian meteorite containing possible fossil evidence for life, the discovery of planets orbiting other main sequence stars, and the continued discovery of organisms living in various extreme environments on Earth. In response to these new findings, NASA has started an ambitious new astrobiology program that funds consortium groups at a number of different research centers and universities, including my own home base at Penn State. Darling has interviewed many of the scientists involved in these efforts, and he has put together a broad, though by no means comprehensive, discussion of the major research thrusts in this field. Chapters 2 and 3, which discuss the possibility that life originated in mid-ocean ridge hot springs or that it utilized complex organic molecules formed in interstellar dust clouds, are particularly illuminating and well researched. Darling's background is in astronomy, and his writing grows increasingly authoritative when he touches on astronomical topics.

If I had a criticism as I read through this book, it was that I wished that the author had included footnotes so that one could check his facts (many of which are controversial, as one might expect in this inherently speculative field). Once I reached the end, however, I discovered that the book is actually quite well referenced. The 20-page "Notes" section contains references to many articles in the refereed scientific literature, some as recent as early 2001. These are listed by page number as they are called on in the book, so they act just like footnotes once one realizes they are there. Hence, even practicing astrobiologists may find this book useful as a literature guide. Practicing astrobiologists may also learn interesting things, as I did, from Chapter 6 regarding non-scientific aspects of the rare Earth debate. But the book is written at a level that should make...