Stanley Thornes Primary Science Book

This is a fascinating book about developments in genetics and evolution in the past twenty years. Sean Carroll is a leading researcher in the field; his lucid writing style and lively approach make this book a "must-read" for anybody interested in the subject. Plenty of illustrations and drawings help to bring the subject to life.

There are several big mysteries in genetics; humans and primates share 99% of their genes, so why is their development so different? The answer lies in "genetic switches" that are encoded in DNA. But these switches have not yet been decoded; they are like the "dark matter" in galaxies--we know that it exists, but its nature is not yet been unraveled.

The first half of the book focuses on how animals develop body parts. Every cell in one's body contains the identical DNA, so how does an embryo "know" which jcells are to develop into a heart, an arm, a finger, a brain, and on and on. Earlier books on evolution that I have read, simply left this as a mystery; hypotheses were described, but none articulated as a real answer. But, this book presents a very persuasive theory, and makes it quite understandable to the layman.

In the second half of the book, Carroll conveys his sense of excitement, as molecular biologists began recently to talk with paleontologists. Remarkable progress in the past decade has shown fossils in a brand new light. Basically, evolution for the most part is not the development of new, mutated genes; evolution is the way in which old genes learn "new tricks". Embryology is shown to play a key role in understanding evolutionary development.

For anyone interested in evolution or genetics, this is the book to read.