Scaling life's right wall

THIS latest assault by Stephen Jay Gould on evolutionary convention targets our vain glorious belief that as a species we are the culmination of natural selection, the sophisticated prize at the top of the evolutionary ladder.

Having unseated historical inevitability (in Wonderful Life: The Burgess Shale and the Nature of History, 1989), Gould now demolishes progress. Forget the old, reassuring narrative. That school book diagram of a primeval ocean soup on the left and a human being on the right - with an amoeba, a fish, a frog, a rat, a monkey etc in between - is a fallacy. Gould replaces ladders with bushes, pathways with systems and the perceived triumph of homo sapiens with the modal bacter, "life's constant paradigm of success".

That giddy elevation of bacteria stands as a geological and zoological marking post in the book, but the central thesis is essentially statistical. And to demonstrate it Gould moves away from his professional territory to a leisure interest: baseball.

In the supposedly golden age of baseball, the truly great hitters (batsmen) were distinguished by hitting successfully, on average and through a season, four out of every 10 opportunities, producing a batting average of .400 or more. No one has managed it since 1941, which, according to traditionalists, proves the game's fall in quality. Gould argues the reverse generally improved overall standards in baseball have eradicated the .400 exceptions.

This "shrinkage of variation" is half Gould's point - it shows how systems work over time and within their real limits (in this case, athletic potential). The other half is more trenchant: we should never have used .400 hitters as an indicator in the first place, because .400 hitting was not a "thing" but the "right tail" of the whole spread of batting. View and judge, if you must, a system by its variation (in this case all ballplayers), not its extremes.

Gould goes on to draw the curve of life. Given it started from a point of nothing and now manifests such complexity, postDarwinians have tended to extrapolate a logic of progress from the principle of natural selection.

Wrong: "The vaunted progress of life is really random motion away from simple beginnings, not directed impetus toward inherently advantageous complexity." Random diversification could and can only expand towards complexity, to the right of any diagram. Moves back to the "left wall" - (nothingness, in effect) come to nothing.

Crucially to us, we occupy the right tail of life's variation. Crucially to Gould, bacteria have always made up the majority of life. Indeed, "the bacterial mode" has resolutely remained as the predominant bulge in the curve of life. Those microbes were always the big news and we are a coincidental side issue.

If the scientific thrust of this book lies in Gould's apparently brilliant analysis of systems, its philosophical momentum is generated by his anti Platonic attack on ideals and essences.

He portrays the classical notion of evolutionary progress (leading 10 man) as arrogant and "parochial", but his own writing is characterised by an undisguised vanity in his achievements with baseball statistics and his boastful boosting of bacteria - bigger and heavier (in terms of biomass), more adaptable, useful, various and long lived than humans.

Jolly informalities ("Well, folks, that's pretty much it"), inane comparisons ("I do realise that bacteria can't laugh ... but remember we can't live on basalt and water six miles under the Earth's surface") and some silly suggestions about culture (the great composers from Bach to. Schubert may have established a "right wall" of excellence) further dissipate the virtues of his scientific cleverness. This book's rhetoric often spoils its intellectual vigour. {CORRECTION} 97010600056