Design for a Life: How behaviour develops 14/02/06. Reviewed by Jon Turney Patrick Bateson and Paul Martin explain how to bake a human.

A newly fertilised human egg measures barely a tenth of a millimetre across. Twenty-five years later it has turned into a creature that might compose a symphony or pilot a jumbo jet. How does this happen?

Patrick Bateson and Paul Martin look at every aspect of this question, but as their title suggests their emphasis is on the many varieties of behaviour. Their measured and readable account has several virtues. Although they relate many animal experiments and observations, their main interest is in humans, which will suit most readers.

They have no time for stale 'nature versus nurture' formulations, but know that simply saying that heredity and environment interact is little help unless one conveys some of the many ways in which the interaction occurs. They reckon the complexity of humans means that poets and novelists are worth listening to along with scientists, and offer a wealth of literary quotation. But they also use their own illuminating metaphors to help their explanations along.

Above all, they are comprehensive, and have interesting things to say about human life as a whole. Although we tend to see development as a process leading up to adulthood, they are clear that there are further developmental stages. In fact they expand the classic seven ages of man to eight, to include gestation.

So the interested human can discover here how the earliest post-conceptual events can influence the growing fetus, what babies can hear in the womb and how well they remember those first cadences, through to the determinants of ageing and decline. In between there are considerations of adolescence, adult identities and sexual preference, learning and skill, instinct and willed choice. All are overlain with a general view that many aspects of behaviour are potentially highly varied, although always within constraints set by genes and evolution, some obvious, some much more subtle.

In fact, the whole book is a recognition of subtlety and complexity, and is clear that only parts of the processes involved are understood. Although they begin with the idea of a developmental kitchen, in which the many ingredients of the individual are baked, this quickly becomes too static an image. There certainly are one-time processes, and critical periods for acquiring certain abilities or realising particular capacities - once the baking is over the cake is made. But there are also more continual, dynamic aspects to development. These are better captured, perhaps, in the notion of a developmental jukebox - with a range of tunes available, which are selected at particular moments. Or perhaps the river of a life can flow down many different channels, but one gradually deepens and captures the whole flow.

This is a book that deserves a place in a selection of volumes on genetics, but one that also puts genetics in its place. The information laid down in the genes has a big part to play in the outcome of the only life any single human ends up leading, but only a part. In a final, musical, metaphor, they propose that development is more like jazz than a performance that follows a set plan. If there is a score, it implies possibilities rather than fixing outcomes. A good note to end on.

Book details

Hardcover 272 pages (September 1999)
Publisher: Jonathan Cape
ISBN: 0224050648