THE MINER'S CANARY: Unravelling the Mysteries of Extinction By Niles Eldredge (Virgin, $119) NILES Eldredge is a man with little time for modesty. In his introduction to The Miner's Canary he writes: ''I set out to write this book with the goal. . . of finding a simple, overarching theory of extinction. I am convinced that I have found it.'' It is a brave claim. So brave that I am tempted to suggest that no one who has read this book has believed him. His overarching theory is an interesting one, but it is not overarchingly new. Mr Eldredge's idea is that there has always been extinction (the dinosaurs did it) and that there will always be extinction. Climatic changes have led to extinction because they have changed the habitat of animals and plants. But they have also led to the evolution of new species. All this is natural. It therefore does not really matter if we lose the spotted owl or the Indiantiger, because extinction, at least on a small scale, is inevitable. What does matter is that people learn to minimise the part they are playing in extinction. Central Park in New York is a fantastic migrant trap and an important stopover for birds each autumn and spring. Conserve those habitats, and species - not all butmany of them - will be saved too. And there's the rub. What Mr Eldredge is saying is that if mankind learns to look after mankind, and therefore mankind's environment, the result will be fewer extinctions. Too much emphasis is being placed by starry-eyed conservationists on those spotted owls in the Pacific Northwest. The clear-eyed view is that in order to save species, we first have to save ourselves. The greatest problem with Mr Eldredge's theory, and consequently this book, is that it remains only a theory. Mr Eldredge is a paleontologist and faced the same problem with The Miner's Canary as Stephen Hawking faced with A Brief History of Time : packaging science for a book-buying public. Mr Hawking got round the problem in a simple way. He decided readers would desert him in droves every time they turned a page to be greeted by an equation. So he left them out. Here Mr Eldredge fails again. There are no equations, but at times his pages are littered with jargon so jarring that it makes you clench your teeth. And why call a spade a spade when you can call it a tool for digging, typically consisting of a flat, rectangular steel blade attached to a long wooden handle? Mr Eldredge has confronted urgent questions, but as a scientist his aim surely must be to take us beyond theory towards fact? In this book, which reads too much like a woolly thesis and not enough like an authoritative journal, it does not appear that hehas done so.