Daniel Tammet interview: Wide sky thinking

But none of these is the most remarkable thing about the young man with whom I'm conversing. More surprising still is the fact that we're conversing at all. As an autistic savant, Tammet's astonishing abilities with numbers and languages come as naturally to him as breathing. Human interaction, on the other hand, was something he had to learn.

As a child, he shunned eye contact, banged his head off walls and ignored other children. Though he could talk at ear-bending length about a subject which interested him, conversation as such was a mystery. Now aged 30, he is a best-selling author, travelling around the world giving interviews and addressing conferences. He easily negotiates the ducking and diving of an interview, the pauses and the changes of gear, the silent signals of body language, the questions-disguised-as-statements. No computer programme has ever been able to match this thrust and parry, but Tammet has managed it.

"I consider social skills a bit like learning a language," he says, in his clear, gentle voice. "I've been practising it for so long over so many years I've almost lost my accent." And he smiles, having also mastered humour, one of the hardest skills of all.

Tammet's autobiography, Born on a Blue Day, was published in 2006. It sold over half a million copies worldwide and has been translated into 18 languages. He says its success surprised everyone. It certainly surprised him. Suddenly, this bookish, bespectacled, private young man was being interviewed on The Late Show with David Letterman.

"The spotlight of the first book was at times uncomfortable," he says, articulating his words with a certain formality, like one speaking a foreign language: fluent, but careful. "There was a lot of interest, a lot written about my personal life and me as a person which I think for anyone would be quite difficult. But I was so gratified that there was so much interest, it came out of nowhere, it allowed me to have this career, to show what I am able to do."

The interviews he gave at the time offer a window into a life still labouring in the shackles of Asperger's Syndrome, a mild form of autism with which Tammet was finally diagnosed in 2005. He followed precise routines (weighing exactly 45 grams of porridge for breakfast every morning, for example) and depended on his partner, Neil, for many everyday tasks. Though he could speak ten languages, he still had trouble knotting a tie.

"I did have a very restricted, regimented life," he says. "There was a kind of happiness there, a contentment, but it was a small happiness within very clear and delineated borders. I did eventually grow out of these, and part of that was due to the success of the book. I had to travel, meet journalists, give speeches and in that process I shed some of that remaining awkwardness, developed confidence and other skills. It was a very positive chance that I was given to open myself up to do that."

With the publication of his second book, Embracing the Wide Sky, the demands on him have redoubled. We meet in London in the office of his publisher, where he is engaged in several days of interviews. He has just done the same in Canada. When not touring, he lives in France, facing the daily challenges of all those who choose to live abroad: the constant use of a second language, the long distance travel to see family and friends.

And here we begin to get at what is truly remarkable about Daniel Tammet. Rather than retreating behind a potentially disabling condition, he saw the opportunities the success of his book provided as challenges to rise to.

"It's a constant struggle. I think if I ever stopped pushing myself I would revert quickly to quite repetitive, restrictive behaviour. But in pushing myself and concentrating on what I can do, I think I can contribute to society. And that gives me the desire to keep pushing, to see what I'm capable of. The thing to do is not to stop."

The conversation we have, in a cramped office in London, is an illustration of how far he has come. We discuss his new book, which is a careful and accessible account of the science of the brain in relation to autism and savant syndrome. But pretty soon we're veering off the script. We talk about GK Chesterton and Kierkegaard, faith and its complex relationship with logic (the subject of the book he is currently writing). We talk about gene therapy and falling in love, Emily Dickinson and Dostoevsky. Far from a one-dimensional prodigy, his is a rich, multi-textured intelligence. A beautiful mind.

There is a sense of recognition in the way he describes the great Russian writer, who suffered from epilepsy, as Tammet did as a child. "When I read him I realised he was someone looking from the outside in at the human condition, drawing on the strange things people don't notice because they're part of the bread and butter of life. He noticed and he wrote about it so movingly and so powerfully." Tammet, too, writes about the world at one degree removed. His perspective gives him fresh eyes and fresh words. He says he might write a novel one day.

AT SCHOOL HE WAS AN ODDITY, a withdrawn child with a prodigious ability with figures. Yet he quickly overturns the stereotypical view of the autistic mind as "rigid, literal, unimaginative". Tammet has synaesthaesia – he sees numbers as colours, shapes and even emotions (37 is lumpy like porridge, 5 is loud, 11 is friendly). Solutions to mathematical problems appear in his mind as complex patterns. It is nuanced, sensual, creative.

Even as a child, he knew he wanted a different life. He studied the social interactions of others with the attentiveness of an anthropologist until he learned them for himself. When he left school, he rose to the further challenge of spending a year teaching English in Lithuania. He learned about his sexuality (he has known he is gay since he was 11) and fell in love. With the help of his partner, Neil, a computer programmer, he started an online language-learning business.

His first taste of fame came in 2004 when he set a European record for memorising Pi to 22,514 places, and became the subject of a Five documentary, The Boy with the Extraordinary Brain. For the programme, he learned Icelandic in seven days and was tested in live interviews on Icelandic television. He went to Las Vegas and triumphed at the Blackjack tables. Yet these achievements were only the visible manifestations of a more complex personal journey.

He says with some sadness that his relationship with Neil was a casualty of that success. "That relationship was very important to me when I wrote Born on a Blue Day four years ago and had that very quiet regimented life. Neil was a big part of my ability to live that life and live it with happiness, to control the symptoms of autism very well.

"When the success of the book came along, I realised that there was so much that I would be able to do with this mind, more than I could do in this quiet, regimented life. I so much wanted, if it was possible, to bring Neil with me into that life, but as I grew, we grew apart. That relationship ended about a year ago, very amicably." Having learned the skills of building a relationship, he had to add the skill of breaking up. Then he met his new partner, Jerome, with whom he lives in an apartment on the outskirts of Avignon. Jerome studied art, and has been introducing Tammet to literature and cinema. It is he who suggested he read Dostoevsky. Having written a book about science, he says he is now drawing much more on his artistic side.

"There are always things I find difficult – being in crowds, remembering faces. I do like routines. I always travel with someone. My life in Avignon is a very quiet one. I have an apartment that looks over the whole city. I can drop into town, but a lot of the time I write from home. In some respects I still live a very quiet, simple life. Nonetheless, there are a lot of positive differences.

"I was very lucky to start this new life. It was difficult at the beginning as it would be for anyone, especially for me. But I thought, as I had as a child, that I would have to do things I haven't found comfortable or easy, keep pushing myself against my limits, if I was to have the life I wanted to have. It's positive because I keep growing, keep changing, I never let myself get lazy."

Embracing the Wide Sky – the title comes from a poem by Emily Dickinson – is a very different book to Born on a Blue Day. Subtitled "A tour across the horizons of the human mind", it shifts the focus from Tammet's own life to explore the scientific research around autism and savant syndrome, and to offer his own clear, careful analysis of it.

Scientists are divided about what causes savant syndrome and whether it is relevant to a greater understanding of human intelligence. There are fewer than 50 autistic savants in the world, many with astonishing abilities in art, music and mathematics which are often accompanied by serious disabilities. Tammet is one of the few who can not only describe his condition from the inside but participate in scientific discourse about it.

"From a young age I knew I had a mind that could do beautiful things that gave me pleasure, but as I got older things have evolved. It's not simply a case of doing sums or learning a language, it's looking at the science of how language works. Rather than being studied by scientists, I can do the science myself, develop my own theories, give my own lectures, correspond with scientists as equals."

Many scientists derive their perceptions of savant syndrome from the writings of eminent neurologist Oliver Sachs, whose book Awakenings was made into the film starring Robin Williams and Robert De Niro. His descriptions of savants in his 1985 book The Man Who Mistook His Wife for a Hat paints them as freakish anomalies, their brains outside the normal human spectrum – an idea that Tammet refutes with typical care and patience.

He agrees with Dr Darold Treffert, the US expert and consultant on the film Rain Man which starred Dustin Hoffman as an autistic savant, who has suggested that savant syndrome may be an indication of mental powers latent in all of us. Tammet believes his intuitive grasp of languages and numbers results from a greater connectivity in the autistic brain which may be inherent in all young children, though we lose it as we grow up. He believes learning that makes use of more intuitive techniques could help people of all ages.

"I'm no computer, or angel, that can do amazing things. It's much more interesting than that. Shakespeare says a part of us is made of the stuff of dreams. Love and perseverance and curiosity and imagination, all these things come into play. It is important to understand that anyone's mind is amazing and can do amazing things."

Recent reports have suggested that we may be just a few years away from a genetic test which would identify the presence of autism in the womb, giving parents the option of terminating the pregnancy. How does he feel about this?

He is measured, careful to say he understands how hard the condition is for those much more severely disabled than he. "It's a very difficult question. I can understand the wish of a parent to know in advance. I would agree with (British authority on autism] Professor Simon Baron-Cohen, there is a worry – many people will have very high functioning autism, like myself, and can learn to overcome or work around the limitations of their condition and draw on their strengths to make a very useful, important, even unique, contribution to society."

Autism, he says, can offer the benefit of a sidelong view, "the ability to see things from a different perspective, the ability not to make the same assumptions about how the world works as everyone else might make.

"There is a risk that you could eliminate a very rich biological source of genius. There is speculation – it's impossible to nail it – that some of the greatest minds through history would have been considered autistic today. If you were to eliminate these genes, you might eliminate people like Einstein, Newton, Wittgenstein."

Yet what is most remarkable about Daniel Tammet is not that one day he could be listed among the great minds of the world – though there is every reason to think that he might be. The truly remarkable thing is the quiet determination by which he has become an ordinary man. Thanks to this perseverance, every day he is becoming more and more himself, which might just be the hardest thing of all.

• Embracing the Wide Sky: A tour across the horizons of the human mind, by Daniel Tammet, is published by Hodder & Stoughton, priced 16.99.