The Evolutionary Tree Of Life
The Very Short Introductions Series of Oxford University Press offers busy readers the opportunity to revisit subjects and to branch out and learn new things. It also allows readers to compare different ways of asking questions. For example, I recently read Terry Eagleton's book in the series, "The Meaning of Life". The book, of course, is a philosophical study which spends most of its time trying to understand the question to determine whether it makes sense. I have read a good deal of humanistic, philosophical literature but little in the literature of science. Thus from Terry Eagleton's book The Meaning of Life", I turned to Michael Benton's almost equally broad book about life's history, "The History of Life" (2008), in the Very Short Introductions series. Benton is the former Head of the Department of Earth Sciences at the University of Bristol. He has written widely on paleontology.
Benton begins his book the way a philosopher might: "It is hard to make sense of the history of life on Earth." He talks about the almost unimaginable periods of time involved, the complexity and incomplete character of the data, and the sheer diversity and strangeness of life in its forms. Yet Benton proceeds carefully and methodically examining the evidence. Even a very short introduction to the history of life requires reference to several disciplines, including biology, geology, chemistry, geography, and physical anthropology, and more. Benton wants to explain what he calls the "evolutionary tree of life" which includes its development from its earliest stages many millions of years ago. The three chief sources of data, Benton points out, are the fossil record, the advances in molecular biology, and techniques in determining the age of rocks.
The book covers a great deal of material concisely and well. Benton writes clearly and with an obvious mastery of his subject. He does not write down to his lay readers. The work includes many photographs and charts which help with the text. The most important of these is the chart of geologic time (pp. 17-18) which is basic for understanding what follows.
In successive chapters, Benton considers the origins of life, the early beginnings of sexual reproduction, the origins of skeletons, the movement of life from the sea to land, the Carboniferous age of life and its extinction, the dinosaurs and their extinction, and the origins of humans. He writes both with the respect for fact of a scientist and with a sense of the wonder of the history and its many twists, developments, and byways. The sense of wonder is particularly apparent in Benton's discussion of the origins of life. Benton discusses controversies among scientists over the data and how the controversies have been resolved, if they have. He shows awareness of the ambiguous place of humans in the history. On one hand, humans are the product of evolution, as are other forms of life. On the other hand, humans are in some sense "special" in that "no other species on earth to our knowledge, writes books, or even reflects on the history of its species."
At the end of his very short introduction, Benton draws some conclusions. Most importantly, he argues that the history of life cannot be regarded as a "narrative" in the way this word is now overused because the development of life has not been teleologically (purposefully) based but is instead the product of evolution. Benton also points out that the evolutionary process has not stopped, and he cautions his readers, in spite of the uniqueness of humans, against thinking that our species constitutes in any meaningful way the "pinnacle" or the "goal" of the evolutionary process. This is wise advice.
The most striking aspect of this history of life for me was the enormity of geologic time. The many millions of years of evolutionary development get stressed in the book. It is difficult to even imagine time frames of this scope.
Over the years, I have been fortunate to visit the Smithsonian Museum of Natural History in Washington, D.C. which has many exhibits that complement this work. But strolling casually through a wonderful museum is no substitute for sustained reading of even a very short introductory book. I haven't thought a great deal about science since graduating from college many years ago. This book and others in the very short introductions series constitute excellent ways to be reminded of important ways of thinking and learning.
Robin Friedman
