In the skeleton gallery, by a skeleton man sat astride his skeleton steed, its bony forelegs rearing like some fossilised horse of the apocalypse, Tim Flannery sounds cheery. Behind him looms an elephant, by his side a skeletal goat stripped of all but horns and teeth fixed in a maniacal grin.

"I think you need a little bit of whimsy," Flannery says, looking about at so much death. This exhibition at the Australian Museum in Sydney was his last flourish while chief scientist here in the 1990s and includes a skeleton sitting in an armchair by an open fire, a display dubbed "Domestic Bliss". Flannery's new book has him in an equally good frame of mind.

Here on Earth: an Argument for Hope, he says, is the climax of a life spent studying the planet and its inhabitants. He has dug into the history of the Earth and humankind and, somehow, found love. "The world is impossible without it and it represents the very best of us," he says.

We meet outside the museum, where Flannery, 54, points out an ibis on a rooftop. He admits missing home on the Hawkesbury River and pulls out an iPhone to show off photographs of wildflowers by the shore.

His new book, which he calls a "twin biography of our species and our planet", starts with Charles Darwin walking at home in Kent in a forest of hazel, privet and dogwood, while shaping his evolutionary theory. Flannery's own sanctuary, which relies on solar power and rainwater, is blooming with flowering yellow bloodwood, pink pigface and pea flowers.

He describes in the book looking out his window and seeing hope in a scribbly gum tree. The indecipherable script written by a beetle on bark shows how evolution by natural selection has created a living, working planet, he argues, based on co-operation rather than savage self-interest. "The beetle cannot live without the tree and the tree cannot live without its invisible partner, a fungus so humble that it cannot be seen, which sheaths intimately the scribbly gum's finest rootlets and improves the tree's access to nutrients.

"Fungus, beetle, bird, tree and the human sitting in its shade, joyed by the song of the bird and the thought that a beetle has learned to write on bark . . . Our world is a web of interdependencies woven so tightly it sometimes becomes love."

The Chinese called evolution "heaven's performance". Flannery likens his book to a play trying to make sense of the complex theatre of life. The writing is more determinedly optimistic than his previous works. The title, Here on Earth, is an echo of the Lord's Prayer, though he long ago rejected Christianity in favour of humanism.

"I believe in the sacredness, if you like, of other people. I'm not arrogant enough to be an atheist because we know so little about the world."

The book is, in part, a retort to what he calls the growing "millennial doomsday feel" about climate change. As we come to know ourselves and our planet, we will be moved to act, he says.

Where does he draw such hope?

"If you look at what we have achieved as a species in 10,000 years, it is unbelievable, going from an organisation that didn't differ very much from that of lions and hyenas to building a global super-organism," he says. "Evolution is on our side. The Earth is the ultimate manifestation of the evolutionary process and it's not one of chaos; it's one of coherence and co-operation.

"The question I was really interested in is not only whether we're going to rise to this challenge of addressing climate change but whether we, as a species, are constituted so as to be able to live sustainably."

He is driven by a "shocking curiosity" to know how things fit together. As a boy in Sandringham, he spent weekends fossicking alone by the cliffs of Port Phillip Bay.

There weren't many books at home for Flannery and his two sisters. His dad, an accountant, directed him towards business. His mum (to whom Here on Earth is, in part, dedicated) once bought her curious four-year-old son half a pig's head from the butcher.

Flannery, famously, failed to win the marks to study science, so opted for English at La Trobe University in 1973. He later transferred to science and, in the early 1980s, wrote a PhD at the University of NSW on fossilised kangaroos, under the supervision of palaeontologist Mike Archer.

He was an eclectic student with florid prose and "prodigious energies", recalls Archer, now professor of biological science at the University of NSW.

The pair fell out in 2003, when Archer was director of the Australian Museum, over the museum's response to the thefts of specimens, some collected by Flannery. Archer prefers not to comment on the stoush, saying only that Flannery "doesn't mingle in science circles really any more".

Some of his peers consider Flannery more salesman than scientist but Archer remains broadly sympathetic: "This kind of affliction is cast at anybody who tries to do work beyond their own expertise. Your colleagues will cock an eye at you and wonder why you are standing up in public when you should be back in the lab."

Friend and collaborator John Doyle, who floated with him down the Murray River on the ABC television series Two Men in a Tinnie, reckons Flannery "would have loved to have been born in an earlier era when there was more of the world to explore. I think he is disappointed so much of it has been discovered."

Doyle says Flannery defines himself by his work. "He is one of the most driven people I have ever met."

That drive took him exploring in Papua New Guinea as a new father, collecting specimens for several months at a time while working at the Australian Museum. His eldest child, David, 26, an astrobiology student in Sydney, recalls him coming home smelling of formaldehyde.

Flannery ended his book Throwim Way Leg, a memoir of his adventures in PNG, by thanking his son and daughter, Emma (now a science student), for loving him despite being "away far too often when you were growing up".

Flannery writes admiringly in Here on Earth about naturalist Alfred Russel Wallace, who described evolutionary theory at the same time as Darwin. "Wallace realised that while evolution by natural selection is a fearsome mechanism, it has nevertheless created a living, working planet, which includes us, with our love for each other and our society."

Flannery sees similar harmony at play in the shade of the scribbly gum or the workings of fire ants, which form collective decision-making systems, not unlike our own democracy.

Every creature is, in some sense, dependent on the rest, he argues. But he leaves dangling the question of whether we might rise or fall together.

"Go through all the horrible things we have done, like destruction of natural ecosystems from 50,000 years ago to the present. But there is also this other side we often don't see," he says. "The book says there is this broad trend towards co-operation and co-evolution but whether it will deliver the right outcome in time is an open question. We still can't say whether we are going to rise to this climate change event. But it opens up the possibility and evolution is on our side."

Here on Earth: an Argument for Hope, by Tim Flannery, is published by Text Publishing, $34.95.

By Peter Munro for smh.com.au
Photo: Helen Nezdropa