Evolution is a complex phenomenon that requires a broad understanding of many areas of
biology for us to appreciate it fully. Moreover, the field has expanded rapidly, especially
since the development of molecular techniques in the past two to three decades. Futuyma's
classic text on evolution (1998) contains 26 chapters totaling 763 pages. To cover the
topic in only eight chapters and 145 pages, as the Charlesworths have done in
Evolution: A Very Short Introduction , is no mean feat.
Their book is one of a series of short introductions, published by Oxford University
Press, covering an eclectic array of subjects that aim to provide an accessible yet
stimulating read for anyone wanting a thorough introduction to a topic. In this small
volume, the Charlesworths have succeeded on both fronts and provide an excellent account of
the core issues for a broad range of readers. One of the reasons for the book's appeal is
that the authors draw on a range of carefully chosen human traits to illustrate their
points. By contrast, most evolutionary textbooks (other than those purely on human
evolution) tend to focus on nonhuman organisms. As with traits in every other organism,
many human and human-related characteristics have evolved via genetic drift and natural
selection, and they provide an effective means of convincing readers of the reality and
relevance of evolution. For example, to explain how mutation can cause the loss of a
function, the authors discuss the relatively poor sense of smell in humans, as compared
with many other mammals, using an example of a vestigial ‘pseudogene’ of a human olfactory
receptor gene. They also discuss tooth decay, enzyme aesthetics, heritable differences,
cancer and other diseases, and the ability to taste and so on.
Although the topics the Charlesworths choose to focus on are certainly appropriate, they
provide only a brief mention of one important process—development. Evolutionary
developmental biology is a burgeoning field that can provide interesting and important
insights into our understanding of the mechanisms of evolution. For example, the absence of
eyes in cavefish, rather than being the result of a degenerative process, might be the
result of selection on genes that govern feeding morphology, a selection process that has
included suppression of eye development (Pennisi 2002). Such developmental mechanisms and
constraints can actually alter the direction of evolution. Although the key forces driving
evolution are usually thought of as mutation, genetic drift, natural selection, and
divergence, the developmental pathways from genes to phenotypes, along with associated
developmental constraints, can also determine the rate and direction of evolution.
In Chapter 7, the authors discuss five topics that have traditionally been hard to
understand from an evolutionary point of view. These ‘difficult problems’ are ageing,
altruism, human consciousness, complex adaptations, and the origin of living cells.
Difficult problems can be interpreted in two ways: those that, although hard to solve, have
either been explained or will eventually be explained by modern evolutionary theories, and
those problems that cannot be fully resolved with our current understanding but leave room
for learning about additional mechanisms or factors. The Charlesworths generally consider
only those problems of the former type—the explained ones. However, I think that some of
the more intractable problems should be described in more detail. For instance, complex
adaptation might be fully explained by mutations and natural selection, but additional
unknown mechanisms might be essential for the evolution of the complex traits. I realize
that opponents of modern evolutionary theory, such as creationists, have often cited these
traditional problems to support their conclusion that modern evolutionary theory is wrong;
but progress always depends on the consideration of new ideas, and there might be important
mechanisms still to be discovered that play a key role in evolution. Describing potentially
intractable problems might also spur on young readers who are thinking of studying
evolutionary biology with the hope that there are still some theoretical battles to be
conquered.
Who is the target audience of this book? For many books, the topics chosen and the
writing style can perhaps provide clues to the nature of the readers. For instance,
The Blind Watchmaker by Richard Dawkins (1990) is a good introductory
book for those interested in natural selection because it seems to be written mainly for
individuals who either oppose or do not understand the role of natural selection. In the
Charlesworths' book, providing evidence for evolution occupies 49 of the 130 pages. They
explain how the similarities between living creatures can be understood in terms of
evolution (Chapter 3) and subsequently discuss evidence from the geographical distributions
of living and fossil species (Chapter 4). My first impression was that this part occupies
too large a proportion of the book. However, Chapter 3 serves as a good introduction to the
basic background of biology, such as the gene, DNA, and cells. When I read a recent article
about a teaching controversy concerning evolution (Scott and Branch 2003), I began to
appreciate the importance—at least in the United Kingdom and the United States—of
convincing readers of the reality and cogency of evolution and evolution theory by astutely
providing them with the evidence to judge for themselves.
In Japan, there seem to be few people who deny the facts of evolution, although there
are many ideologically motivated books opposing natural selection and Darwinism. To
convince creationists of evolution is usually extremely difficult, if not impossible,
because they will never doubt their assumption that God created humankind. Education of
young and curious people, however, can make a difference. This is where I think the book
will be most successful, but this book should not just be limited to young people—I can
recommend it to anyone who wants to know about evolution. Moreover, I can recommend it to
Japanese students not only as an introduction to evolution, but also as an exercise in
reading a well-written and engaging English text.
