Still wondering how to grow a new limb

Every human baby has a starting point when egg and sperm meet during fertilisation. It also has a much longer history, in the unbroken evolution that links the genes that guide its wondrously well-orchestrated development with the earliest forms of life. Add the history of attempts to understand these things, and you have the three narrative strands that Henry Gee weaves into his book.

Gee begins with a sketch of embryonic development that emphasises the beauty and complexity of what we are trying to account for.

Towards the end there is a look at some of the latest thinking about the organisation and regulation of gene expression, in which genomes are modelled as self-referential networks, and a little intriguing speculation about how such a view might change our understanding of evolution. In between, though, history is the main business.

The result was the beginning and end of a rather interesting book wrapped around a long middle that was less compelling. That is not to say that all popular science books should deliver the latest findings. Nor does it suggest that the history of science is not fascinating in its own right. It is just that with the welter of gene and genome books of the past 30 years, much of the history of heredity has become rather familiar.

There are some felicitous touches in the writing, as when a discussion of the operator binding site on DNA that switches a gene off under the influence of a regulatory protein informs us that "mutating the operator is a bit like bombing a runway so that planes can no longer land there". But it is hard to feel these add enough value to the story to justify retelling.

I thought this a shame because Gee, a senior editor at Nature , is obviously well informed about the latest science, and the shorter sections on genomic analysis are intriguing. He is less sure-footed in the final chapter, in which he takes up the potential implications of genomics and gene technologies. Here, he castigates journalists for hyping designer babies while still exhorting the reader to prepare to think about a world in which people might be able to grow extra limbs or change sex as easily as changing clothes. And he gives no real guidance about how to do this.

I was left hoping that, now that Gee has scratched his historical itch, his next book will make more of his talent for explaining the latest research.

Meantime, if you want an elegant reflection on the history of heredity, I suggest you unearth a copy of Francois Jacob's The Logic of Life .

Admittedly it was written too long ago to tell you about Hox genes, genomic networks or, indeed, the Human Genome Project. But as a popular history that captures the successive changes in thought about generation and reproduction, it remains hard to beat.

Jon Turney is consulting editor (science) for Penguin Press.