Ever since the first bright spark invented fire, the recipe for genius has been one of culture's most alluring quests. And yet, historically, our conception of genius has been surrounded by a de facto mystery. The idea that it could be explained would, under certain conceptions, appear to run counter to its essence.
In Roman times, genius was considered to be innate: a trait bestowed by the gods at birth. But with the dwindling of the gods who, from antiquity through to the Enlightenment and beyond, had been the notional source of creativity, it has fallen to others to do the explaining. Even modern science has been somewhat reluctant to take up the challenge of exploring the nature of creative genius. The gods have been replaced by unpredictability: it seems that genius eludes any singular systemic explanation. Part of the problem for science has been attempting to distil a working definition of genius that removes its more subjective historical and cultural associations. This is far from easy. One tenet of the term is that a genius must be recognised as such by the relevant experts in the field. By that reckoning, if Albert Einstein had never published his theories, he would be barred from the title. Scientists have tried to unpack genius into components as various as intelligence, structure and function of the brain, madness, levels of disinhibition, even our genetic inheritance.
Just after the First World War ended, the psychologist Lewis Terman tried to find out the developmental mainspring of genius. Are you born with it? If you've got it do you have to look after it? Does it guarantee deathless glory or can having it spell catastrophe down the line - "Early ripe, early rotten," as the saying used to go? He selected a group of boys and girls with high intellectual potential (IQ scores between 135 and 200) and for the next 70 years recorded everything about them, from their preference for certain types of food through to their professional status. The results run to six volumes. Perhaps surprisingly, these children - who came to be known as the Termites - did not turn out to be the scrawny geeks that we might expect. Rather, they bore many of the hallmarks of a master race: they were taller, physically healthier and more economically and socially successful than their averagely endowed counterparts. And yet, to Terman's dismay, not one Termite emerged as a creative genius. Only one, Robert Oppenheimer, generated an enduring cultural artefact - the US television sitcom I Love Lucy - and few would argue for that show's immortal sublimity.
So if IQ doesn't underpin our creativity - what does? And in the terms of neuroscience, what role might the maturation of the brain play in laying the foundations for genius? Brain development is on a hectic timetable, given that several trillion synaptic connections must be laid down for the brain to function at average levels. During early pregnancy, brain cells are fashioned at 250,000 per minute, and this continues at a ferocious rate for the first few years of infancy: connections form that allow you to crawl, walk, then talk. There are recognised critical periods when we must use our brain or risk losing faculties such as language. The process of constant organisation and reorganisation continues into early adult life and, some say, beyond.
During adolescence, the brain "prunes" millions of the now redundant branches it has established. The pruning is a process of adapting the organ to its environment that accomplishes, somewhat counter-intuitively, an increase in our cognitive capacity. Interestingly, a colleague of mine, Professor David Skuse, has highlighted a dip in teenagers' social intelligence, speculating that this is probably because their brains are being rewired at that time. The timetable of our cognitive development seems to preclude childhood genius - yet our experience suggests otherwise.
Einstein was 16 years old when he wrote his first scientific paper on the subject of magnetism and the aether. Ten years later, in 1905, he had a moment of revelation while riding in a tram, looking back over his shoulder at a receding clock tower: "A storm broke loose in my mind . . . the solution came to me suddenly with the thought that our concepts and laws of space and time can only claim validity in so far as they stand in a clear relation to our experiences." He had, in one leap of genius, arrived at the special theory of relativity - in essence, the faster you move, the slower time goes. Over the next six weeks, he exhausted himself scribbling down the mathematical details, which looked to all intents and purposes like so many hieroglyphs: beautiful perhaps, but nonsensical. Yet these 31 handwritten pages would change the course of our history. What was so different about this young man?
Last year, I interviewed the neuroscientist Professor Marian Diamond, of the University of California, Berkeley, for a programme investigating the nature of Einstein's genius. She smiled as she explained: "They arrived floating in a Kraft mayonnaise jar." She was referring to pieces of Einstein's brain that had been sent to her by Dr Thomas Harvey, the pathologist who neglected to put the brain back in the body at autopsy. When Diamond sliced and stained Einstein's brain, she found it had more glial cells (which provide physical and nutritional support for neurons) in one particular area. But why? It's probably because Einstein in effect "worked out" part of his brain doing hours of calculations, bringing about a reorganisation of certain connections that enhanced his mathematical ability.
Beyond intense mental exercise, however, it is likely that Einstein's brain was innately endowed with the potential for extraordinary performance. In the 1990s, Dr Sandra Witelson analysed the external surfaces of Einstein's brain, publishing her findings in the Lancet. The overall brain size was unremarkable, but on both sides, just above where the ears would be, she found an unusual pattern of grooves and ridges in the same area that Diamond had encountered the excess of glial cells. The external structure of the brain is dictated early on in development. It may be that the idiosyncratic fusion of specific regions of the brain gave him an advantage in taking on board certain types of information.
At the time of Einstein's death, the function of these brain regions was unknown. A few years ago, a colleague of mine, Dr Elizabeth Isaacs, was investigating children with problems in mathematical calculation at school. She found that the children had less brain matter in the left parietal lobe, the same area in which structural abnormalities had been observed in Einstein's brain. Therefore, it would appear that part of the brain has been hard-wired for maths calculations. It is not that you have a multiplication table in your head, but that you have a predisposition to mathematical skill, which has proved over millennia to be advantageous to our problem-solving abilities and hence our survival.
My bet is that Einstein was born hard-wired for maths. When placed in the right environment, his brain reorganised and flourished, allowing his ideas to be realised. Yet this does not account for those moments of revelation, where insights occur in a flash. Even Einstein admitted as much: "When I examine myself and my methods of thought, I come to the conclusion that the gift of fantasy has meant more to me than any talent for abstract, positive thinking."
In 1959, R E Lubow and A U Moore introduced the concept of latent inhibition: the ability we have to filter out irrelevant stimuli. Thus we can read a book, walk down the street and hold a conversation, or sleep in a noisy room. Yet this ability may hold back our creativity. Creative people are less able to filter out irrelevant thou-ghts, permitting them to make more creative associations. Is this why Coleridge could see Xanadu only in a dream, where the Nobel Prizewinner Otto Loewi saw nerve impulses, and Friedrich Kekule saw the benzene ring? These accounts suggest the work of unconscious processes described by Gertrude Stein: "It takes a lot of time to be a genius; you have to sit around so much doing nothing, really doing nothing." Lowering your filtering threshold to allow the mind to wander may permit information to pour in obliquely, facilitating extraordinary associations.
In neuroanatomical terms, it is the frontal lobes of the brain that control many of our higher cognitive functions, our social behaviours, our abstract thought processes, our novel ideas and planning. The frontal lobes are not fully developed until the early twenties, and perhaps only then permit the creative mind to link up fully with all our experience that is now imprinted on our organised brain. A few years ago, I came across a patient who had never done any artwork in his life until, following a stroke in the frontal area of his brain, he suddenly felt an insatiable need to create paintings, drawings and sculpture. He now finds it difficult to inhibit irrelevant thoughts coming into his mind, yet it is precisely the novel associations that these thoughts engender which seem to provide the basis for his creativity. It may be that the stroke has caused a disinhibition of brain pathways, allowing his newfound creativity to surface. Studies by Professor Allan Snyder have suggested that if you "knock out" parts of the frontal lobes in normal volunteers, you can improve their creativity. Perhaps whatever was keeping my patient's artistic talents dormant was damaged just enough to allow them to emerge. Somewhere, it seems, a floodgate was opened.
A distinction must, however, be made between the child genius and the mature creative genius. The former tends to have an early predisposition for one task alone. The latter may be focused in one field, yet works with an insightful vision that may be a product of the disinhibited mind.
Dr Mark Lythgoe is a neurophysiologist at the Institute of Child Health, University College London. He will discuss "What is Genius?" on 30 September at the Barbican, 6pm.
The Young Genius season runs at the Barbican, London EC2, to January 2006