Biology, 5/e                     Raven, Johnson
		About the Book

Preface

Biology was published in 1986 and, in the dozen years since its initial publication, has sold almost half a million copies. These have been exciting years for the science of biology, marked by great advances in many fields. The twin impacts of gene technology and evolutionary thinking have literally transformed the science of biology. In the last year alone, great strides were made in understanding AIDS and developing therapies for cancer, in sorting out the role of productivity in promoting ecosystem stability, and in tracing human origins in Africa. Much of the excitement inherent in scientific advance is reflected in controversial reports that have received considerable publicity. Recently, for example, we saw the reported cloning of an adult sheep, the suggestion of ancient life on a Mars rock, and the Nobel Prize recognition of a claim that mad cow disease is caused by infectious proteins called prions.

The need to keep Biology current with these rapid advances is an obvious reason why we revised this text again this past year. A second and equally important reason is that the way biology is being taught has also undergone a sea change. There is far more emphasis today on the teaching of concepts than there was a dozen years ago, and this has led us to make significant changes in how we present material. Technology plays a greater role in teaching than it used to, both with interactive CD-ROMs, and more recently with the wealth of information that can be accessed via the internet.

The Approach of this Revision

Our approach to revising Biology has been guided by five considerations, each of which has influenced in a significant way how we have revised each chapter of this book:

Evolution is the core of the science of biology, and from the first words we wrote, has always been a central theme of Biology. Evolution provides a context for understanding broad biological phenomena, such as the marked differences in anatomy and physiology among the vertebrates. It also provides a context for exploring the details of quite specific processes, such as the rapid evolution of the HIV virus during the course of an AIDS infection.

Exploration-the way in which scientists investigate the unknown-is a key element of our presentation of biology. Throughout this revision we provide detailed explanations of how experiments have led to our knowledge of life's processes. We chose the cover of this edition to highlight this exploration. Hidden within the image are many elements not immediately obvious at first look. Examine the cover closely for faces!

Structure-and-function provides an orientation for examining how cells and multicellular organisms work. The cause-and-effect relationships that underlie anatomy and physiology are a core element in organizing how we present much of the material in this text. Understanding such mechanisms provides an important element of integration as students learn biology.

What We Did in this Revision
Learning Modules

A key element in our attempt to direct student focus toward concepts has been to reorganize the internal structure of each chapter into a series of discrete learning modules, each occupying one or two pages (a few use more), and ending with a summary. The concept outline that appears at the beginning of each chapter thus represents the conceptual skeleton of the chapter, allowing students to readily grasp how the concepts relate to one another and to the overall theme of the chapter.

This sort of modular organization has been used for several years in a variety of biology texts. It has proven a very effective way to point students toward the key ideas on which they need to focus. At first glance it might appear too confining an approach for a majors text like Biology, but we were surprised to find how naturally the material fell into this organization. The material was in almost all cases already arrayed into conceptual blocks, as this is the natural way to teach biology-making the individual treatments fit on one or two pages neatly was largely a matter of adjusting the sizes of figures. In practically no case was material cut to make a treatment fit. Far more often, we found ourselves adding new material. So the entire previous edition is still here, and even more. It is just presented in easy-to-grasp pieces. Traditionally, page layout happens late in the production process, long after the authors are finished with the manuscript. Beginning each major topic at the start of a page, the hallmark of this modular organization, would be practically impossible under that arrangement. In this revision, by contrast, each page of each chapter was layed out by the authors as we revised that chapter. Content and presentation were no longer independent, but rather part of the same creative process. We feel it has made for a much more effective teaching tool, while not in any way compromising content.
Expanded Coverage

In this revision we have greatly expanded our coverage of botany to eight full chapters. One four-chapter part, Plant Form & Function, covers elements of plant anatomy and physiology, and another, Plant Growth & Reproduction, covers plant reproduction and development, including a chapter devoted specifically to plant molecular biology. We have also greatly expanded our coverage of ecology, adding significant coverage of many current issues. Population and community ecology, weak points in previous editions, have been particularly strengthened.

In every other chapter of the text, we have added material where significant advances have taken place, from our understanding of how the cell cycle is controlled, to recent findings about the course of human evolution. Few chapters escaped significant improvement in coverage.
New Art Program

When Biology was first published in 1986, it was the first full-color majors text ever, although that is hard to comprehend in today's world of splashy five-color texts. In intervening years we have added to the art, improving individual pieces but inevitably introducing a variety of styles and conventions. In this revision we have gone back and started from scratch, introducing an entirely new art program. Every figure in the text has been reconsidered and redone, so that all illustrations are now consistent in style as well as content. Biological molecules and cell structures, for example, now are consistently color-coded to aid in student comprehension. Cross-sections of biological membranes look the same wherever they are encountered, and so do other elements of cell and body structure. This approach enrolls visual learning as a powerful ally in the teaching process.
Technology

In the last decade, and particularly in the three years since the last edition of Biology, sweeping changes in the use of technology have greatly altered how biology is taught in our classrooms. While the initial loudly-trumpeted advent of laser discs had little impact (thousands of extra images added little worth to biology teaching, just as a painting is rarely improved by giving the artist more paint), fully interactive CD-ROMs that allow students to explore freely and carry out meaningful experiments are now making real contributions to biology teaching in classrooms all over the country.

You will find a new CD-ROM tutorial available with this fifth edition of Biology. The Essential Study Partner (ESP) is available free with the fifth edition of Biology and contains high quality 3-D animations, interactive study activities, illustrated overviews of key topics in the text, and supplementary quizzing and exams that students will find extremely valuable. This is a study tool that your students must have, so they receive it free.

An even greater-in fact, explosive-impact is being had by access to the internet. Every text now has its own web site. Our web site, http://auth.mhhe.com/biolink, provides a wealth of opportunities to the student and teacher. These include readings, sample tests, and other elements traditionally provided in study guides, as well as a wide range of other enrichments. The three most important, in our judgment, are monthly updates written by us that provide the student with current information about rapidly-changing areas of biology, internet links provided with each chapter that let students see the range of internet opportunities available, and enhancement chapters written by us that allow students and instructors to explore rapidly changing areas of biology in more depth. The three enhancement chapters included with this edition are Conservation Biology, Dinosaurs, and The Revolution in Taxonomy. We did not wish to lengthen an already-long text, and so have placed these chapters on our website, http://auth.mhhe.com/biolink, where anyone using our text will have access to them.
Acknowledgments

We have been teaching biology together for 26 years, and are consistently surprised, each and every year, by how much fun it is. This book has been part of that fun, written in the spirit that biology ought to be engaging and interesting as well as comprehensive and authoritative. This fifth edition of Biology would not have been possible without the contributions of many others. Stuart Fox made major contributions to the animal biology section, James Traniello to the animal behavior chapters, and Don Briskin & Margaret Gawienowski to the chapter on plant molecular biology. Kingsley Stern provided detailed reviews of the botany section, and teachers around the country made numerous suggestions that have improved the book substantially. Every one of you has our heartfelt thanks.

A major feature of this edition has been the reformatting of the presentation into conceptual modules. This formidable task would not have been possible without the effort of Megan Jackman, our on-site developmental editor. Her intelligence and perseverance played a major role in the high quality of this book.

As any author knows, a textbook is made not by a writer but by a publishing team, a group of people that guide the raw book written by the authors through a year-long process of review, editing, fine-tuning and production. This edition was particularly fortunate in its book team, led by Elizabeth Sievers, a developmental editor who proved both a delight to work with and a reliable guide to the complicated process of getting the book out on time and in the best possible shape.

As always, we have had the support of wives and family who have seen less of us than they might like because of the pressures of getting this revision done. As this is the fifth edition of Biology, they have become accustomed to the many hours this book draws us away from them, a hidden price of textbook writing of which they are fully aware.

Acknowledgments would not be complete without thanking the generations of students who have used the many editions of this text. They have taught us at least as much as we have taught them.

Finally, we need to thank our reviewers. Every text owes a great deal to those faculty across the country who review it. Serving as sensitive antennae for errors and sounding boards for new approaches, reviewers are among the most valuable tools at an author's disposal. Many improvements in this edition are the direct result of their suggestions. Every one of them has our sincere thanks.

Expert Reviewers

Vernon Ahmadjian  Clark University
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