We enter a new century with this sixth edition of Biology, one that is exploding
with excitement in biology. This first year of the new millennium has seen the
completion of the Human Genome Project, with the full sequence of the human
genome now available for research and exploration. Embryonic stem cells were
cloned for the first time in the year 2000, and offer the potential for curing
a wide range of ills, from spinal cord injuries to diabetes. Golden rice, a genetically
modified crop to which has been added a battery of genes that overcome deficiencies
in vitamin A and iron, was planted for the first time in Asian fields. Neurobiologists
for the first time caught a glimpse of the molecular basis of learning. Even
taxonomy, that bastion of conservative judgments, seems to be undergoing a sea
change, with molecular phylogenies forcing the redrawing of many family trees,
from angiosperm plants to insects and other arthropods.
There probably has never been a more exciting time to learn biology. Adding together
the years, Dr. Raven and I have been teaching biology for more than 70 years,
and neither of us can remember any time as fraught with promise as today. We
started teaching in the sixties, also exciting times. In those revolutionary
years the black box surrounding the gene machine was stripped away, revealing
for the first time how DNA achieves the constancy and diversity that are the
hallmarks of life. For 40 years researchers have been amplifying that picture,
learning in ever-greater detail how life works.
In the last few decades, the pace of biological research has accelerated, as
we have learned for the first time how to manipulate genes. In agriculture this
has led to waves of controversy, in medicine to advances universally applauded. But
no matter how one views genetic engineering, no one questions that it is changing
the science of biology in profound ways.
What is important about these changes in biology, what excites us like no past
year, is the potential to influence our health, and that of our world. Biology
as a science can --indeed, must --be more than simply a trip to the zoo, an
investigation of what living things are like and how they work. These things
are important parts of biology, of course, the knowledge that provides the core
of the science. But it can't stop there. The knowledge of biology that has been
gained, especially in the last decade, provides us with a tool of unprecedented
power to improve the human condition and lessen human impact on the world we
share with life's other creatures.
It is with this sense of a science alive with promise that we set out in the
first year of this new century to produce the sixth edition of Biology.
Significant Enhancements to the Sixth Edition
Every revision of a successful text starts with a plan to update areas where
advances have occurred. Thus the initial plans for this sixth edition of Biology
were to correct any errors detected by its many users, and to incorporate new
findings in rapidly advancing areas of research. In publishing terms, this was
to have been a "light"; revision. However, that is not what happened. Inspired
by the suggestions of reviewers, we found ourselves adding chapters, overhauling
the way in which key chapters were organized, adding material and then more
material soon we were knee-deep in a significant revision. Much of the
focus of this sixth edition revision was on evolution, ecology, and botany,
areas where there was an opportunity for exciting improvement. To revise these
chapters, we recruited two young energetic biologists to provide fresh perspective. They
brought with them new approaches, fresh ideas, and up-to-date knowledge of their
areas of expertise. Indeed, it has been so much fun to work with them that in
future editions they will join us as full coauthors of the text.
Ecology and Evolution
Professor Jonathan Losos, our colleague at Washington University, has revised
the evolution and ecology sections of the text, bringing more experimental science
into our discussions. Presentation of the experimental data used to derive key
conclusions and concepts is key to this revision. Our goal is to better aid students
to understand how the concepts arose from the research. For this reason, you
will see that graphs and charts are more plentiful in these chapters.
Professor Susan Singer of Carleton College has revised the botany chapters. The
botany sections have benefited from a new approach where plant development takes
center stage. A plant developmental biologist, she has placed the traditional
discussions of evolutionary influences on plant form and function into a developmental
context. Thus while evolution is still presented as the underlying explanation
for the character of vascular tissue, seeds, flowers, and fruits, the developmental
processes that produce these organs are now given more prominence. This does
not lessen the evolutionary character of the treatment, but rather serves to
amplify it. Throughout all the botany chapters, there is an enhanced emphasis
on the molecular aspects of plant life. Understanding the molecular underpinnings
of plant form and function allows students to more clearly understand the evolutionary
changes that have shaped them.
New Chapter: Conservation Biology (Chapter 31)
In the fifth edition, we presented a discussion of conservation biology on the
Biology web site, as an "enhancement chapter."; The response to this material
was so overwhelming that we have included such a chapter in this edition of
our text. In our own classroom teaching we find students to be keenly aware of
the problems of dwindling natural resources, and the need to tackle the issue
concretely. We feel a chapter focusing on conservation biology will be appreciated
by students and useful to professors.
Genomics "Enhancement Chapter";
The rapidly advancing field of genomics is so key to the future of biology that
we felt it necessary to discuss it in some way in this sixth edition. Including
a chapter in the text seemed rather pointless --so much of what we would cover
will have changed after the first year. So we turn again to an "enhancement chapter."; We
used enhancement chapters to expand information for the fifth edition of Biology,
and as you see from above, after fine-tuning the conservation biology chapter,
we now include it in this edition. The enhancement chapter on genomics can be
found at http://www.mhhe.com/raven6. This new chapter expands upon the discussion of gene technology to present and
explain the advances now being made with genomics. While the chapter discusses
the technology involved and the genomes that have been uncoded, it focuses on
the significance of this information to biology as a science, and on what it
could mean to the future of medicine, agriculture, and many other fields.
Real People Doing Real Science
We have added an inquiry-based learning experience at the beginning of every
Part that walks a student through the process of scientific inquiry by examining
a particular experiment. We have titled this feature "Real People Doing Real
Science."; After briefly reviewing the significance of the experimental question
being addressed, we take the student through the actual experiment, discussing
experimental design in depth, and then briefly describe the results and conclusion. This
is but the first part of the learning experience. The student is then directed
to the Biology sixth edition web site for an in-depth examination of the experiment. There
a student can read the actual published research paper, allowing students to
become more familiar with the primary literature. Then the student can carry
out a "Virtual Experiment"; where he or she is able to manipulate the parameters
of the experiment and obtain data for analysis. We provide on-line questions
and discussions to help the student better understand the thought process behind
A Thorough Revision
| In addition to the extensive revisions of the ecology, evolution,
and botany sections of the text, and new chapters on genomics and conservation
biology, we have thoroughly revised the rest of the text as well. Many chapters
now sport radically different organizations, benefiting from extensive reviewer
input. Pedagogy has been improved as well. We have included phylogenetic guideposts
throughout the discussions of diversity to clarify for the student where
each group fits in the tree of life. (You will find these guideposts in chapters
35, 36, 37, and 44 48.) || (8.0K)|
The Chemical Building Blocks of Life (Chapter 3)
The organization of this chapter has been turned on its head, presenting lipids
before carbohydrates. This gives a greatly improved sense of the relative biological
importance of these macromolecules, and actually makes the material easier to
The Origin and Early History of Life (Chapter 4)
The discussion of ideas about the origin of life is now much more open-ended,
stressing competing hypotheses and the key role of assumptions for which there
is little data.
Photosynthesis (Chapter 10)
The internal organization of this chapter has been reworked to make it easier
for students to understand how the many concepts covered in this chapter relate
to one another.
Patterns of Inheritance (Chapter 13)
This chapter has been reorganized to incorporate the discussion of human genetics
earlier in the chapter and then to use human examples as a means of explaining
Cellular Mechanisms of Development (Chapter 17)
We have moved the discussion of cellular development up earlier in the text,
immediately following the discussion of gene expression, to reinforce key molecular
Altering the Genetic Message (Chapter 18)
Many recent advances in cancer research are highlighted, with greater emphasis
on genes governing metastasis and angiogenesis.
Gene Technology (Chapter 19)
New topics such as biochips and transgenic rice have been included and rapidly
advancing areas such as stem cells and ethics and regulations have been updated.
The Evidence for Evolution (Chapter 21)
We have expanded this chapter to include a complete discussion of the evolution
of the horse, and have expanded the discussion of artificial selection as a
means of showing the power of selection on the evolution of species.
Population Ecology (Chapter 24)
We have added and expanded the discussions of population distributions, ranges,
dispersal mechanisms and human effects in examples replete with actual data.
Animal Behavior (Chapter 26) and Behavioral Ecology (Chapter 27)
We have amplified these two chapters, moving them to the ecology section, a
more logical place to teach these topics.
Dynamics of Ecosystems (Chapter 28)
We have greatly expanded discussions of interactions among trophic levels and
the controversial matter of how species richness influences community stability.
The Biosphere (Chapter 29)
We have expanded the discussion of evolutionary responses to environmental variation.
Evolutionary History of Plants (Chapter 37)
We now include a discussion of the "Deep Green Project"; that demonstrated the
green algal origin of all plants.
The Plant Body (Chapter 38)
We included a discussion of the genes involved in development of stomata, trichomes,
root tissues and leaves.
How Plants Grow in Response to Their Environment (Chapter 41)
This chapter was extensively reworked and many new topics were added and expanded
such as acid growth hypothesis of auxin actions, plant defense responses, cytokinin
involvement in organ regeneration and crown gall tumors, brassinosteroids and
oligosaccharins, transgenic tomatoes, initiating flowering, and circadian clocks.
The Noncoelomate Animals (Chapter 44)
This chapter now includes a molecular reevaluation of the evolution of the metazoan
Arthropods (Chapter 46)
New molecular data calls into question traditional classification of arthropods
based on external characteristics.
Locomotion (Chapter 50)
We have added a discussion of modes of locomotion that ties together the concepts
presented in the chapter.
Circulation (Chapter 52)
We have added a section on heart disease, explaining that heart disease is preventable
and begins with establishing a heart-healthy lifestyle early.
Sensory Systems (Chapter 55)
We have broadened the coverage in this chapter to include more examples of nonmammalian
The Immune System (Chapter 57)
This chapter has been completely reorganized to improve clarity and understanding. The
presentation of topics now more logically follows the process of the immune
response in the body.