When Richard Dawkins, the 74-year-old biologist and proselytising atheist, realises that his photograph is to be taken, he rushes to get one of the ties hand-painted by his wife, the former Doctor Who actor Lalla Ward. It’s a broad white one with penguins on it.

Afterwards he becomes charmingly animated about “these selfie things” that people keep asking him to him pose for. “But I try not to be grumpy,” he says, and later he is very polite when a man comes over to shake his hand.

He’s not the most engaged interviewee, however. He looks distractedly out of the window when he has finished with a subject, and he’s reluctant to talk about things unmentioned in his new book.

That book, Brief Candle in the Dark: My Life in Science, is a spirited trawl through 40 years of his professional life, from the publication of the groundbreaking The Selfish Gene through to his evolution from Oxford academic to public intellectual. It’s a sequel to An Appetite for Wonder, which depicted his early life as the surprisingly religious Kenyan-born son of a colonial civil servant. “Everybody was [religious] then, weren’t they?” he says. Does he remember what that felt like? “Oh yes. I try to convey a little bit of it . . . going to confirmation classes and listening to the vicar, a very nice man and an avuncular figure, telling us about all this nonsense and taking it seriously and struggling to understand it.”

He doesn’t think he ever had a burning ambition to be an academic, he says. “I didn’t really discover a passion for science until I was sat in Oxford in my second year . . . I’ve interviewed scores of schoolchildren coming in to read zoology, and they’re nearly all birdwatchers or bug-hunters. I wasn’t. I was interested in the philosophical, deep questions: Why do we exist? What’s life for? How did it start?”

He was a relatively young man when The Selfish Gene exploded into the world, in 1976. The gist of it is that evolution happens not at the level of the individual or the species but at the level of the gene. “I didn’t realise how revolutionary that was,” Dawkins says. “I thought I was just expressing what all biologists believed, but it turned out that I was changing the minds of some biologists . . . It did cause a bit of a stir.”

The book was a surprise bestseller, and people wanted to see more of Dawkins. The first documentary he was asked to do was on The Selfish Gene itself. “I turned that down because I was too frightened,” he says. “About 10 years later I was asked to do a couple more documentaries by the BBC, and I agreed to do those. It was a fairly gradual process.”

Brief Candle in the Dark provides snapshots of his work as both an academic and a publiciser of science, and it has, as he puts it, lots of funny anecdotes about people and scientists that he has met. He talks with particular enthusiasm about his stint, from 1995 to 2008, as Simonyi professor for the public understanding of science. He is a proud advocate of knowledge for its own sake. He has always been driven, he says, by “a love of truth, a love of clarity, an almost physical discomfort at obscurity and a desire to make things clear”.

Zeitgeist

Did public perception of him change when he wrote The God Delusion, his religion-baiting bestseller from 2006? “I’m not a very good observer of the zeitgeist,” he says, a little coolly. “You’re telling me about things that changed in my role as a public intellectual. I don’t really notice that kind of thing.”

He wanted to write The God Delusion first in the late 1990s, but his literary agent told him it wouldn’t fly in the United States, so he shelved the project. When it was eventually published he was seen as being at the vanguard of the “new atheism”.

Three similar books came out at about the same time – by Sam Harris, Daniel Dennett and Christopher Hitchens – he says, “so it’s not unreasonable for a journalist to slap a label on that. We were called the Three Musketeers before Christopher came along. Then we were named the Four Horsemen.” Why did the books arrive together? “In America it probably had something to do with George Bush. I think that’s not implausible: he invaded Iraq because God told him to.”

The book put Dawkins on the front line of the culture wars, but he denies that it’s particularly angry or hard hitting. “We’ve got so used to religion being beyond criticism,” he says, “that even mild criticism comes across as being more polemical than it really is. If you compare the language used in The God Delusion with the language used by theatre or restaurant critics, it’s pretty mild.”

He has been criticised for focusing on a fundamentalist version of religion and ignoring more nuanced varieties. In Brief Candle in the Dark he admits to finding debates with moderate religionists frustrating. “They’re often very nice people with whom I have delightful conversations,” he says. Rowan Williams, the former archbishop of Canterbury, is “almost impossible to argue with because he’s just so nice, and Fr George Coyne, who was the head of the Vatican Observatory, is a highly intelligent scientist. He seemed to me to be pretty much an atheist and to be agreeing with everything I said.”

Is it possible that in those interactions he’s arguing at cross purposes, because those are people for whom truth isn’t an absolute?

“Yes!” he says with surprising enthusiasm. “I’m starting to realise that. I think there are people for whom truth doesn’t really matter. I met this when I went to Lourdes for television and I spoke to a resident priest there, who was Irish, in fact.

“I asked him questions about how many cures had been achieved, and he told me, and I said, ‘That’s about what you’d expect statistically if nothing was going on.’ And he said, ‘Yeah, that’s true,’ and I said, ‘Why do you speak of miracles, then?’ And he said, ‘Well, I don’t really think of miracles. The real miracle for me is people’s faith.’

“I meet this again and again. For many of these, what we’d call sensible religious people, the truth is almost irrelevant: what matters is feelings and perceptions, and I’ve never really got that. For me what’s true really matters.”

He pauses to consider something “that scientists are supposed to pay lip service to, which is that we don’t really know what is true. All we know are hypotheses that haven’t yet been falsified.” Then he adds, defiantly, “But there are certain things that damn well are true.”

At one point, discussing the Oxford tutorial system (in which groups of two or three students spend an hour with their teacher at least once a week in each of their subjects, discussing a topic in depth), Dawkins notes that the wider world has a lower tolerance for taboo-busting statements than academia does. “Academics are prepared to discuss almost anything. Something rather outrageous like, ‘Why are we against Cannibalism?’ ” They will sit down and say, “ ‘Well let’s explore: why do we disapprove of cannibalism?’ ”

This reminds me of the type of outrage-inciting pronouncements he makes on Twitter. When I tell people I’m interviewing Dawkins almost everyone wants me to ask why he tweets so much. His argumentative social-media persona currently seems to overshadow his career. But when I ask about Twitter he says, “I’ve nothing to say about that, really. It’s not in the book.”

He mentions Twitter in the book, I say. “Very briefly, yes.” He laughs. “I think that will be [for] volume three.”

Later I ask if he regrets any arguments he has become embroiled in. “Not really, no.”

Even on Twitter? “That’s in a way an artefact of the brevity of the 140 characters, but there are also misunderstandings, sometimes due to the fact that in a long series of Twitter exchanges you have to know the context of the previous tweets in the conversation. If you come to it late you miss the point.”

This seems a little disingenuous. Dawkins has tweeted many things that seem deliberately inflammatory. After a young American Muslim, Ahmed Mohamed, was arrested when a teacher suspected that a clock he had made was a bomb, Dawkins took to Twitter to deny that the boy had “invented” the alarm clock and to wonder publicly about his motivations.

He has chipped in, uninvited, to comment on the Muslim world’s failure to produce many Nobel Prize winners and to undermine western feminists whose struggles he, as a wealthy white man, finds petty.

But it turns out that I get only one more shot at a Twitter question. I ask about the time Dawkins responded to someone saying that she would be conflicted if pregnant with a baby who had Down syndrome by tweeting: “Abort it and try again. It would be immoral to bring it into the world if you have a choice.”

He sees it as a simple matter of logic. “I just fell afoul of people who were against all abortion anyway,” he says. “If you’re going to abort for any reason, then prior knowledge of a problem that the child is going to face would be a better reason than because you feel like having an abortion.

“If you’re against abortion you should be even more against abortion because it’s a whim rather than because of a humane feeling toward the child. But this is nothing to do with this book.”

Ultimately, Dawkins believes, it’s okay to tell the truth as he sees it, even if other people might find it hurtful. “Yes,” he agrees, but adds, “I wouldn’t go out of my way to intrude on somebody’s death bed and disabuse them of their hopes.”

Consolation of religion

Does he understand why some people feel the need for religion? “I suppose I can, yes. Consolation has often been mentioned. I find myself remarkably unpersuaded by that argument . . . Everyone thinks that people on their deathbed are consoled by the fact that they’re going to go to heaven, but they’re terrified that they’re going to go to hell.”

Other things console him. “Human love, science, music, poetry. Just the joy of living.”

And many things excite him. The EWI, for example, an electronic musical instrument that he plays like a clarinet; the spread of “memes” (a concept he originated), which he discusses, referring to a statistical study of Twitter rumours during the London riots; and his work over the years modelling artificial selection with computer simulations.

Was that like playing God? “You can think of it as a god,” he says, “or you can think of it as a farmer selecting cattle or a dog breeder breeding dogs.”

The world is magical enough, he says, without metaphysics. “People are so obsessed with the football or getting to work or the ordinary mundane things of life that they forget that,” he says. “Imagine that you were a visitor from Mars suddenly plonked down here. It’d be fascinating . . . But we’re all so used to it, inured to the fascination by the anaesthetic of familiarity.”

Yet, Dawkins is still fascinated by it all. “How could anyone have a soul so dead as not to be intrigued about where they come from and what the universe is all about?”

Brief Candle in the Dark: My Life in Science is published by Bantam Press