Edward O Wilson is one of the architects of that bleak philosophy called sociobiology. In his 1978 classic On Human Nature, Wilson describes the human mind as a device for survival and reproduction, with reason as just one of its various techniques.

"The first dilemma, in a word, is that we have no particular place to go. The species lacks any goal external to its own biological nature."

He spells it out: all the drive, wit, love, pride, anger, hope and anxiety that characterise the species Homo sapiens are simply there to perpetuate the biological cycle.

All of which makes it even more fun to discover that this seemingly austere nihilism flowered from an enchanted childhood enriched by a passion for the fauna of the old American South, and then – only notionally – impoverished by the loss of an eye to a spine from a poisonous little fish; by a grateful experience of ramrod military education; by compulsive achievement in the Boy Scout movement; by a sincere investment in the hymns and passions of the Southern Baptist Church; and by an old-fashioned Tom Sawyer faith in the ideals of honour, duty, courage and standing up to bullies.

The story could as easily have been an exculpation of failure: a sorry chronicle of a lonely boy, child of divorced parents, son of an ultimately suicidal depressive alcoholic, farmed out to strangers, bullied at school, left to his own devices, allowed to play with guns and knives, dragged from town to town and school to school, increasingly obsessed with insects, snakes and amphibians.

But nothing in Wilson's telling makes it seem unhappy, or at least not for very long: here is a resourceful, resilient child who makes the best of his surroundings. It is a sunlit story of the warm south: Mark Twain rather than Tennessee Williams, complete with drive, wit, love, pride, hope and so on.

And it is beautifully written. The story opens with the memories of a seven-year-old on Paradise Beach in Florida, mesmerised by a medusa, which he describes with delicacy and precision. Somehow this early fascination with life's prodigality, with wet, slimy or creepy-crawly things, becomes systematised and methodical.

The young Wilson learns quite early on that he wants to be a scientist. He is in luck: he meets people who encourage him; he works his way through college; he becomes what he dreamed of becoming, a myrmecologist (specialising in ants); he ends up at Harvard and his increasing expertise in the ant world of the Americas and the Pacific somehow enables him to begin to see the big picture: the puzzle of life on Earth.

It isn't clear, despite the clarity of the memoir, quite how the dreamy child turns into the focused scientist – some dreamy children just become dreamy adults - but these steps from daydream to determined endeavour usually involve a mix of random encounter, enthusiasm and opportunism.

Wilson becomes more than just a great ant man. He extends the lessons of the ant heap to the panorama of evolution. He becomes a theorist of biodiversity, evolutionary biology and biogeography, and one of the patron saints of conservation science.

Ironically, as he becomes a scientist, he begins increasingly to write like one. "I believed deeply in the power of reductionism, followed by a reconstitution of detail by synthesis," he declares in his chapter on island biogeography, and in the same paragraph a colleague becomes "enamoured of" a subject.

On the other hand, who could not applaud a Harvard don who writes of another Harvard don, his contemporary the double helix discoverer James Dewey Watson: "I found him the most unpleasant human being I had ever met."

But such episodes are just turbid pools in the limpid stream of memoir. Wilson goes around the world, grubbing for ants in Mexico, New Caledonia, the New Hebrides and Australia, makes ant history in Sri Lanka, marries happily, wins academic awards, writes great books, and wins a Pulitzer prize.

He gets involved in furious ideological debate about genetic determinism. On a public platform somebody literally pours cold water on him and his arguments – one forgets how polarised the politics of biological science then seemed – but he says, "I received almost no hate mail, and never a death threat." Right to the end, he maintains the old-fashioned courtesy of the South.

He concludes that he would do it all over again, but this time as a microbial ecologist, and begin his research not in the jungles of the Pacific but rather cut his way "through clonal forests sprawled across grains of sand" and travel in "an imagined submarine through drops of water proportionately the size of lakes".

Naturalist is an unfinished story about a profound and increasingly thoughtful love affair with life itself: all life.

It isn't obvious that this literary biophilia – the word is Wilson's own coinage – somehow enhances my chances of reproductive survival, but it certainly enhanced my summer.

Thanks for several ideas for books to debate (and I know that at least two of you suggested another Wilson title). But club member Hypocorpse got in promptly with a request for Gaia: A New Look at Life on Earth by James Lovelock (1979). It's not a big book, but it certainly punched above its weight.