Books: Back on the Beagle

Almost Like a Whale: The Origin of Species updated by Steve Jones Doubleday, pounds 20, 402pp; Can a science writer now - however good - add to a timeless classic?

Of the great figures whose world-systems have dominated our century, only Darwin remains in current fashion. It is hard to open a daily newspaper without finding it full of Darwinesque references, from the medical to the business pages. And in a research world which moves so fast that it is rare to find a scientist referring to a paper published more than five years ago, the fact that The Origin of Species, whose first edition appeared in 1859, is still the source of lively debate not just among historians of ideas but biologists themselves, speaks to its extraordinary impact.

So it must have seemed an inspired publishing move to get a leading geneticist to update it. And who better than Steve Jones, whose Reith lectures on genetics in 1991 and subsequent television series, have revealed a brilliant capacity for communicating science to a wide public.

Evolution simply means change over time. That the living world had so changed was already commonplace by the mid 19th-century. Darwin's great insight was not about the fact that evolution had occurred, but about its main mechanism, natural selection, the term he invented to describe his theory. This can be condensed into three propositions,which once stated are so obvious that "Darwin's bulldog" - the zoologist T H Huxley - kicked himself: "how stupid not to have thought of that".

They are:

(1) Like begets like, but with minor variations.

(2) All organisms produce more offspring than can survive to breed in their turn.

(3) Those offspring best fit for the environment in which they find themselves are most likely to be those that survive long enough to breed, thus increasing the "fitter" variants.

Hence species are not immutable but are gradually transmuted over time, in response to environmental pressures. It was this conclusion, that species can change, that seems so obvious to us now. Yet to Darwin it was "like confessing to murder" and ran counter to biblical views. So much so that he brooded over it for some 20 years and was only galvanised into publishing by the independent discovery of the idea by Alfred Russel Wallace. He rushed The Origin into print as a mere "sketch" of the big work he planned but never wrote. The first edition sold out within a day, and Western cultural life was lastingly changed.

Darwin didn't have it all his own way, then or later. Lacking an understanding of genetic mechanisms (Mendel's work, although available to him, was not recognised by the scientific world for another 40 years) he was vulnerable to his critics and the subsequent editions of The Origin squirmed and shuffled in an attempt to answer them. When Mendel was rediscovered in the early 1900s, genetics was seen as a rival theory of evolution.

Darwinism fell into a decline from which it was not rescued until the 1930s, when the mathematical biologists Ronald Fisher and J B S Haldane in Britain, and Sewall Wright in the US, showed how genetics and natural selection could be reunited in what became known as "the modern synthesis".

As Darwin put it, The Origin is "one long argument". So he opens his case by discussing, not natural selection, but the ways in which breeders artificially select fancy pigeons, producing tumblers, pouters and many other weird forms. This shows that species can be selectively modified; if by humans, why not by nature?

So the argument is built up, step by irrefutable step, drawing on his own experience during his long Beagle voyage around South America and on the huge international correspondence he conducted over the intervening decades. A major chapter, particularly modified in subsequent editions, deals with objections to "my theory" before the book concludes with a marvellous coda. The whole account, plainly but grippingly written, is enriched by Darwin's meticulous observations of the living world.

Steve Jones notes that, by contrast with philosophers and historians, few biologists read The Origin today. I myself most recently read it only a few months ago, in a small boat aptly called Beagle III, in the company of a mixed group of biologists and social scientists as we retraced Darwin's own visit to the Galapagos. The text is mesmerising, and even for so accomplished a writer as Jones, a hard act to follow.

His method is to take each of Darwin's chapters, and rewrite them from present-day biological knowledge and new examples (thus Aids and dog breeding replace Darwin's pigeons), concluding each chapter with the original summaries. There is no reference to human evolution in The Origin, much to Jones's manifest relief. Thus he need give no more than a passing and dismissive reference to the current enthusiasm for so-called evolutionary psychology, which claims to explain our social organisation and its problems by reference to assumed adaptations in our stone-age past. Jones takes for granted that readers know what DNA is and have a general knowledge of modern genetic ideas.

His problem is that while Darwin was really engaged in argument, his successor 140 years later has no one to argue with. That evolution and speciation occur, and that natural selection is one of their main mechanisms, is so taken for granted, even if much misunderstood, that there is no argument to be had. Except, of course, with the daft band of religious creationists, who aren't likely to read the book anyhow. If anything the boot is on the other foot, and the argument needs to be had with a new breed of quasi-religious ultra-Darwinian fundamentalists seduced by misleading metaphors about "selfish genes".

The consequence is that each chapter reads more like a rich string of natural-history anecdotes, more or less loosely connected to the themes of variation, selection, the geological record and so forth, rather than an argument. The richness is almost overwhelming, and I am awed by Jones's reading.

There can be few even professional biologists who can fail to learn something new. My own particular shame is never to have calculated that only 10 percent of the cells in a human body are actually human (the others being bacterial, fungal, etc). Jones's range and relaxed style inevitably permits some misleading statements, such as calling testosterone the "male" hormone (both males and females produce it). And, in keeping with Darwin's original, there are no references, so it is hard for the reader to trace back some of the more recondite statements to their source.

Perhaps, too, because he doesn't need to argue, Jones's text is almost overstuffed with metaphorical, anthropomorphic and allegorical writing (as when parasites "creep" into a host's body "with regret"). Sometimes metaphors are piled on top of each other so profusely that the original point is obscured - very different from Darwin's abstemious style.

A more serious limitation is that by sticking so properly to the task of illustrating evolution and explaining it by natural selection, there is no opportunity to discuss the very live debates among biologists about either the extent of other mechanisms of evolutionary change (drift, founder effects, molecular drive, contingency) or the mechanisms of natural selection itself (levels of selection from single genes to populations, punctuated equilibrium, structural constraints on change). There's more than one long argument to be had here.

Oh, and that enigmatic title? It comes from one of Darwin's very few speculations about the power of the selective process he analyses. Reading an account of the unusual habit of a black bear in north America, observed swimming for hours with an open mouth catching insects, "almost like a whale", Darwin permitted himself to muse that, granted enough time and the utility and strength of the habit, there could be no reason why in due course bears could not evolve into whales.

And why not, if such odd creatures as two-legged upright, speaking, writing and culture-creating humans could evolve from tree- living apes? The choice of such a title is indicative of both the strength and weakness of this hugely enjoyable, but almost over-rich book.

Steven Rose is professor of biology at the Open University