Carl Zimmer - The Tangled Bank: An Introduction to Evolution, Second Edition

SECOND EDITION

SECOND EDITION

AN INTRODUCTION TO EVOLUTION

Carl Zimmer

Front cover: Ambulocetus by Carl Buell

Title Page Credits (left to right): Wayne Lynch/All Canada Photos/Superstock; Esther Beaton; Tom McHugh/Science Source; ZUMA Press, Inc./Alamy; J.B. Miller/USFWS. Left to right: Abigail Allwood; Klaas Lingbeek-van Kranen/Getty Images; Steve Gschmeissner/Science Source; Marie Read/Science Source; Hoberman Collection/ Superstock, Inc.

2014 by Roberts with W. H. Freeman and Company.

All rights reserved

ISBN: 978-1-3192-6876-3 (ePub)

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To Grace, for growing our garden together

IT IS INTERESTING TO CONTEMPLATE AN ENTANGLED BANK , clothed with many plants of many kinds, with birds singing on the bushes, with various insects flitting about, and with worms crawling through the damp earth, and to reflect that these elaborately constructed forms, so different from each other, and dependent on each other in so complex a manner, have all been provided by laws acting around us. These laws, taken in the largest sense, being Growth with Reproduction; inheritance with is almost implied by reproduction; Variability from the indirect and direct action of the external conditions of life, and from use and disuse; a Ratio of Increase so high as to lead to a Struggle for Life, and as a consequence to Natural Selection, entailing Divergence of Character and the Extinction of less-improved forms. Thus, from the war of nature, from famine and death, the most exalted object which we are capable of conceiving, namely, the production of the higher animals, directly follows. There is grandeur in this view of life, with its several powers, having been originally breathed into a few forms or into one; and that, whilst this planet has gone cycling on according to the fixed laws of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved.

Charles Darwin, The Origin of Species (1859)

FEW SOUNDS ARE AS JOYFUL for authors as the thud made by a mail carrier dropping the first printed copy of their book by the front door. Years of effort suddenly take shape as paper, ink, and covers. But for textbook authors, there is another sound thats just about as sweet: receiving the first printed copy of the second edition of a textbook.

By the time a trade book about science reaches the bookstore, its probably already out of date. Science rolls forward, as researchers perform surprising new experiments or stumble across fossils lurking in the ground. Coaxing a trade publisher to update a book is next to impossible, for a whole host of economic reasons. Fortunately, textbook publishers think otherwise. A new edition of a textbook can be an update on a scientific field, rather than a cultural artifact. It is thus with great pleasure that I present the second edition of The Tangled Bank: An Introduction to Evolution.

The first edition, published in 2009, was an experiment of sorts. A growing number of colleges were offering evolution-related courses to nonbiology majors, but they had no textbook specifically tailored for their students. Having spent two decades reporting on evolutionary biology for newspapers and magazines, as well as writing trade books on the topic, I decided to create just such a textbook.

The response has been immensely gratifying, and its encouraged me as Ive revised The Tangled Bank for a new edition. Much of the work Ive put into this edition has involved surveying recent scientific literature for new studies that advance our understanding of evolution. Those advances have included everything from research on our Neanderthal relatives to experiments on cancer-fighting drugs based on evolutionary principles.

The second edition contains new figures that better illuminate the concepts I discuss in the text. Ive also updated the overall organization. In response to a number of requests, for example, Ive written an entirely new chapter near the end of the book dedicated to human evolution. There I integrate the concepts introduced earlier in The Tangled Bank, such as phylogeny, genetic drift, and sexual selection, to help readers gain a deeper understanding of our own species.

From the start of this project, Ive tried to make The Tangled Bank as readable as possible. The second edition does not have some of the standard pedagogical conventions. New terms are not set off in boldface, for example, and the book does not contain problem sets or summaries. Instead, I define new terms in the text itself. Students who want to check their understanding can now consult a new study guide, produced by biologist and journalist Alison Perkins. For more information on purchasing the study guide, visit http://www.roberts-publishers.com.

Although the second edition of The Tangled Bank is new in some important ways, it does not waver from the goals of the first edition. I hope that it continues to help a wide range of students come to appreciate the majesty and explanatory power of evolution.

CARL ZIMMER, GUILFORD CT MAY 2013

SECOND EDITION

The earliest whales, such as the 47-million-year-old Ambulocetus, still had legs. Their anatomy gives us clues to how whales made the transition from land to sea.

O ne of the best feelings paleontologists can ever have is to realize that theyve just found a fossil that will fill an empty space in our understanding of the history of life. Hans Thewissen got to enjoy that feeling one day in 1993, as he dug a 47-million-year-old fossil out of a hillside in Pakistan. As he picked away the rocks surrounding the bones of a strange mammal, he suddenly realized what he had found: a whale with legs.