A living planet for how long?

As long ago as 1941 an essay by Julian Huxley on "The size of living things" kindled my interest in what is now called biodiversity. That interest is as lively today as it was at the first reading. Similarly, In Search of Nature, though a modest and unpretentious-looking book, makes such stimulating reading that Edward O. Wilson might be regarded as a one-man recruitment bureau for tomorrow's biologists. "Life of any kind", he tells us, "is infinitely more interesting than almost any conceivable variety of inanimate matter". His essays on ants alone would make any intelligent teenager instantly vow to become a lifelong myrmecologist. What do you do if you find ants in your kitchen? Mind you don't step on them, says Wilson, then offer them crumbs of coffee-cake. Just in case, like me, you do not always have coffee-cake available, he assures us with grave authority that they are fond of tuna and whipped cream too. "Get a magnifying glass," he says. "Watch closely. And you will be as close as any person may ever come to seeing social life as it might evolve on another planet."

The reader will notice how very carefully - with mays and mights - as well as economically, Wilson chooses his words, though, as for getting so close to his favourite subjects, this advice may not be appreciated by those who, like me, have been subject to famously and furiously brief encounters with tropical India's red fire ants; or Australian enthusiasts who come into contact with their "bulldog ants" (Myrmecia), which are over two centimetres long. These ants bite and sting with such ferocity that, far from pampering them with coffee-cake and whipped cream, few observers would care to study them at close quarters, according to another authority.

Nevertheless, any form of life in which the smallest species are so small that a colony of them could comfortably dwell in the brain case of the largest species, while others have evolved kamikaze soldiers designed like miniature hand grenades to explode when protecting their colonies, is liable to overwhelm the imagination. Moreover, because insects provide us with the only known alternatives of organised societies among living things, they inevitably invite comparison with our own. Wilson is quick and sharp to point out some of the more poignant differences, though: for example, while we humans send our young men to war, ants send their old women. Only a superb raconteur-biologist such as Wilson could explain why that is so.

His essays on ants tend to leave one gasping for breath, literarily speaking, at the cost of ignoring his other subjects in this delightful volume of essays. Yet he is equally enchanting in his accounts of sharks and snakes and New Guinea's birds of paradise. It is when he comes to paradise itself, the planet with which we share this wonderful and unbelievable diversity of living things that, like so many of us, he is compelled to face the question as to whether Homo sapiens is suicidal. "The human species is", he declares, "an environmental hazard", and goes on to dismal speculation as to whether perhaps a law of evolution is that intelligence usually extinguishes itself.

Yet after rehearsing details of the devastation we have wrought and are doggedly continuing to commit in this paradise that is Gaia, and coming out strongly on the side of the environmentalists - as opposed to those who comfort themselves with a complacent it-will-all-come-right-in-the-end attitude - Wilson does not believe that humanity is suicidal. He sees us as entering a bottleneck unique in history, constricted by population and economic pressures. We can pass through that bottleneck "only by halting population growth and devising a wiser use of resources than has been accomplished to date".

Sadly, many of us consider these unachievable goals, though an occasional gleam of hope comes unforeseen from unexpected quarters. Buddhist monks in Thailand, taking advantage of the population's absolute belief in their sanctity, have ordained as monks, with appropriate and elaborate ceremonial complete with saffron robes, many thousands of rainforest trees, thus ensuring their immunity from the chainsaw. They are currently and vigorously continuing this novel and profitable practice. Catholic nations might take note.

Wilson is co-editor, too, of Biodiversity II. But although these two books are basically about the same thing, they could not differ more sharply in their approach, nor in the audiences at which they are aimed. Here we have a more academic and, to my mind, a less important book. It is also one which I approached with a heavy heart, knowing what I was about to be told. This book is a sequel to the 1988 Biodiversity which may, as the publishers claim, have been a bestseller, but which could not have been more encouraging than its successor. Here, essay after essay catalogues the diversity of living things but, far from entertaining us like In Search of Nature, it paints a predictably dismal picture asking not only how many species we have actually got, but how much time we have got in which to preserve the last of them.

To quote Wilson again, "some scientists and policy makers have worried that the magnitude of the biodiversity we now know to be present in the world's habitats is so enormous, the cost of exploring and documenting it so overwhelming, and the number of biologists who can analyse and document it so small that the goal of understanding the diversity of the world's species is unattainable". Yet he insists that the central message of this volume is, to the contrary, that the potential benefits of knowing and conserving this biodiversity are too great and the costs of losing it too high to take the path of least resistance. How far, then, does the book succeed? Biodiversity, the planet's most valuable resource, is on loan to us from our children, the book declares piously on its fly-leaf. How true that is, but how far do books like this help us realise it?

Famed among many other things as a determined atheist, J.B.S. Haldane was once asked what, were he to believe in God, he would consider His most striking aspect. After a moment's thought Haldane is said to have replied: "An inordinate fondness for beetles". And indeed, as Biodiversity II reminds us, beetles make up no less than 25 per cent of all known species. But does it matter? Does biodiversity matter at all? We rightly lament aloud to hear that not a day passes without there being one less tiger on this planet, for that is the reputed rate at which these beautiful animals are being slaughtered to ensure the health and vitality of elderly and presumably wealthy Chinese. The same is true of many other of the more spectacular forms of plants and animals. We are little concerned about those beetles and worms beneath our feet, but they are in fact of as much importance to the well-being of life on earth as tigers or pandas, rhinoceroses, blue whales or giant sequoia trees. As Paul Colinvaux of the Smithsonian Tropical Research Institute in Panama recently pointed out, "the fear that loss of diversity has practical costs is at its most frightening when we acknowledge that we do not know what most living things do, or even what they are".

This book tells us a great deal about what living things are and do, but despite the decade that has passed since the publication of its archetype, it has very little in the way of encouragement to offer. I for one must admit to being wearied by constant reminders, as I am with this book, that "life on Earth takes many forms and comes in many sizes, from microscopic one-celled plants to blue whales and human beings", and look more earnestly for practical ways of preserving and not merely cataloguing it. To quote Colinvaux again, "what of the ethic of asking tropical peoples to spare their forests when we have turned England into a safe arable garden?" The ethic, perhaps, lies in population, over which even federal ministers of some developing countries have openly confessed to have lost control, as well as in the fact that the diversity of life in tropical countries is far greater than in temperate ones. England, after all, is not home to tropical rainforests, coral reefs or mangrove swamps, environments where the greatest biodiversity is to be found. As Thomas E. Loveday points out in this book, a characteristic pattern of biodiversity is a general increase in the number of species as one approaches the equator.

Here again perhaps the East offers inspiration to us: orthodox Jains of India are not only strict vegetarians but will not eat anything such as tubers or roots that grows beneath the ground, for fear of destroying life-forms such as earthworms and other soil invertebrates. Jain monks and nuns even go to the extreme of wearing face masks, not to protect themselves against city pollution as an increasing number of us are now forced to do, but as tokens of their veneration for all forms of living things - even those they might inadvertently inhale and destroy. Both these books are evidence enough that any jaundiced scientific scorn for Thailand's vegetable monks and India's vegetarian Jains is parochial.

The central message of Biodiversity II, we are told, "is positive and provides confirmation of the quantum advance in biodiversity studies since Biodiversity helped define the problem and place the topic high on the international agenda". What "quantum advance" might be I cannot say, but that "a cost-effective solution to the biodiversity crisis lies in the collaboration of museums, research institutions and universities, the pooling of human and financial resources, and the shared use of physical and institutional structures that already exist", I very much doubt.

These arguments may have a strong appeal down the aseptic and austere corridors of western universities, but living as I do some way from those sober environments, I am inclined to a different view. Biodiversity II is sub-titled "Understanding and Protecting our Biological Resources". It certainly goes a long way in learnedly and elegantly presenting the first of its stated goals, but is no more successful than a wealth of other books in showing us how to achieve the second. This is yet another volume, I feel, preaching to the converted, certainly of little attraction or appeal to the heretic.

Harry Miller is a fellow, Zoological Society. He lives in Madras.