He said that he could not condemn the “mild paedophilia” he experienced at boarding school. “I am very conscious that you can’t condemn people of an earlier era by the standards of ours,” he says in an interview published today in The Times Magazine.

“Just as we don’t look back at the 18th and 19th centuries and condemn people for racism in the same way as we would condemn a modern person for racism, I look back a few decades to my childhood and see things like caning, like mild paedophilia, and can’t find it in me to condemn it by the same standards as I or anyone would today.”

Professor Dawkins, an evolutionary biologist, describes in a new autobiography how a master at his Salisbury prep school “pulled me on to his knee and put his hand inside my shorts”. He writes that the episode was “extremely disagreeable” and that other boys were molested by the same teacher, but concludes: “I don’t think he did any of us any lasting damage.”

In the interview Dawkins, 72, addresses his disagreements with the former Chief Rabbi Lord Sacks and the physicist Peter Higgs. On the subject of abuse he emphasised that he sought to explain it, not condone it.

Asked whether the uproar over recent abuse scandals was partly a result of what he called the “shifting moral zeitgeist”, Dawkins says: “I think we should acknowledge it ... But the other point is that because the most notorious cases of paedophilia involve rape and even murder, and because we attach the label ‘paedophilia’ to the same things when they’re just mild touching up, we must beware of lumping all paedophiles into the same bracket.”

Peter Watt, director of child protection at the NSPCC, called Dawkins’s remarks “a terrible slight” on those who had been abused and lived with the effects for decades.

He said: “Mr Dawkins seems to think that because a crime was committed a long time ago we should judge it in a different way. But we know that the victims of sexual abuse suffer the same effects whether it was 50 years ago or yesterday.”

Peter Saunders, founder of the National Association for People Abused in Childhood and himself a victim of child sex abuse, said that Dawkins’s comments were worrying and unhelpful. He added: “Abuse in all its forms has always been wrong ... Evil is evil and we have to challenge it whenever and wherever it occurs.”