Darwin In the Genome by Lynn Helena Caporale, McGraw-Hill, $24.95, ISBN 0071378227 Reviewed by John Bonner
IN THE lottery of life, only the holders of the winning tickets will pass on their genes to the next generation. So it makes sense, as biologist Miroslav Radman pointed out, to buy as many tickets as you can, with as many combinations of numbers as possible. Variety is the key to success.
Yet it has always been assumed that an organism had no direct control over the process of generating diversity 鈥� it was the product of random mistakes in copying DNA in germ cells. Indeed, an organism would try whenever possible to reverse such mutations because most do nothing to improve its survival chances or are harmful.
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As evidence builds up from studies of the genomes of various species, it鈥檚 beginning to seem that mutations aren鈥檛 always random: they occur more often in some genes than in others. Genes that make proteins involved in the simple chores of cellular housekeeping can be virtually identical in widely different species. But those that may give a selective edge 鈥� such as those coding for the toxins used by predatory sea snails to catch their prey 鈥� change rapidly from generation to generation.
In Darwin in the Genome, Lynn Caporale explains the many ways that organisms shuffle the DNA pack to deal a winning hand. The nomadic chunks of DNA known as transposons and even the repeat sequences once dismissed as 鈥渏unk鈥� now seem to be mechanisms for generating this genetic variety, she says.
Caporale, a biotechnology consultant working in New York, subtitles her book 鈥淢olecular strategies in biological evolution鈥�, but rejects any suggestion that its contents undermine classical Darwinian theory. The term 鈥渟trategy鈥� is not used to imply that the process is driven by a preordained plan, as creationists would argue. Rather, she says, it is used to indicate mechanisms that 鈥渉ave the effect of anticipating and responding to challenges and opportunities that continue to emerge in the environment鈥�.
Starting from her time as professor of biochemistry at Georgetown University Medical School in the early 1980s, Caporale has argued that the messages in the genetic code are more complex and subtle than the old 鈥渙ne gene 鈥� one protein鈥� hypothesis would allow. In this book she has marshalled compelling evidence to back up her case. However, she is not a natural communicator and has been let down by weak editing.