Science: Big questions for little people: A family dig for buried treasure is a major attraction at Edinburgh's science festival, says James Cusick

OVER THE weekend there were a staggering 200 archaeological finds in a scientific dig in the middle of Edinburgh's Princes Street Gardens. Beneath a discreet, white-domed tent on a site boxed in by wooden slats, workers unearthed treasures from neolithic and stone-age Scotland, Roman coinage, 15th-century weaponry, and a ginger-beer bottle from 1920.

Eight-year-old Elizabeth Innes from Broughty Ferry left the dig area with a certificate to prove she had found the ginger-beer bootle. She had just taken part in the fifth Edinburgh International Science Festival.

The simulated dig, part of the Discovery Dome exhibition, highlights the festival's 'hands-on' and 'please ask' philosophy. Archaeologists placed the 'treasures' in sand. For pounds 1.25, it was the job of the guest workers to unearth them with an archaeologist's trowel, clean them in water, have them evaluated by a museum curator and place them in context. Adults supposedly supervising their offspring were clearly delighted to be offered a chance to join in the

digging.

Bruce Durie, the new director of the festival, believes participation in science is essential to an understanding of everyday existence. Popularise science? Unnecessary, he says. It is popular already. Who had never switched on a light bulb, seen a weather forecast or listened to a CD player? Science touches every aspect of daily life; what is crucial is to participate in its exploration.

During the two weeks of the festival, the unanswered, the unquestioned and the unimaginable are paraded. Tomorrow, R McNeill Alexander, professor of zoology at Leeds University, will deliver a lecture: 'How Dinosaurs Ran'.

'Some dinosaurs were huge,' he will tell his audience. Professor, ask the sales manager at Hamleys in Regent Street, London. They are enormous. The lecture, in fact, will be a serious evaluation of dinosaurs as a 'problem of engineering'.

The festival, now in its second week, has touched on the popular and the obscure. Dr Robin Keeley of Scotland Yard's forensic laboratory defended DNA fingerprinting against legal doubts. The law, he said, was

not accustomed to dealing with new

technology.

While exhibitions and activities abound - subjects include the beauty of physics, re-creation of ancient music, cartoons on the world of particles, and a travelling mathematical circus - the serious side of science is taken seriously indeed in Edinburgh.

Is the independence of universities being compromised? A gathering of biomedical scientists, concerned at the fostering of profit-oriented companies within academia, aired their fears to Dr Charles Sanders, chief executive of the pharmaceutical company Glaxo, USA.

In one of the most challenging and controversial lectures, Dr Lynn Margulis, professor of biology at the University of Massachusetts at Amherst, argued that science facilitates an understanding of our co-existence with nature.

Dr Margulis is the originator of the symbiotic theory of cell evolution. She said biological science and traditional evolutionists tended to focus too much on the most recent chapter of the Earth's life, when plants and animals began to appear. 'I say that everything happened before that. It just happens to be small. And we tend to ignore it because it doesn't talk back.'

Symbiogenesis (by her definition, the association of different species of bacteria, which eventually change from being two different organisms into one, and then evolve into plants and animals) is far from accepted in traditional evolution circles.

Dr Margulis told the Edinburgh conference that random mutation, central to Darwinian theory, is not enough to explain evolutionary diversity. The fusion of two organisms, making a third, lent biology its own arithmetic. 'The physicists will tell you that three and two makes five. Biological addition is different. Three and two makes one.'

She talks in almost conspiratorial terms about bacterial organisms. 'They've been trading their genes for 3,500 million years. They've been trading quietly and now they're saying: 'We got along before you came. We'll get along after you.' '

Dr Margulis claims that well before the appearance of Homo sapiens, these organisms learnt how to mine metal. 'If they hadn't precipitated iron, we wouldn't be driving cars.' Like all good communicators, Dr Margulis has a sense of the absurd. She laughs at a Gary Larson (The Far Side) cartoon in which one organism says to another: 'I was thinking of going multi-cellular, but I didn't want to get involved in any cult.'

The festival agenda this week includes Professor John Baker from Glasgow University on the new science of nanoelectronics: engineering with single molecules. Forget the primitive microchip. The future, according to Professor Baker, will be an electronics revolution based on molecular and biological switches.

The festival also examined Formula One racing-car technology. In their lecture, writer Graham Gauld and Benetton Formula One engineer Willem Toet said car aerodynamics - essentially increasing downforce and improving road-holding - had been developed to such a level that it was theoretically possible for a current Grand Prix car to drive upside down on the roof of the tunnel at Monaco, creating sufficient downforce to hold it in place. The lesson in this? Never travel in a taxi if Ayrton Senna is driving.

The Edinburgh International Science Festival continues until 24 April.