Dan Brown at an event to promote his new novel Inferno, at the Freemason’s Hall, London. Photo: Reuters

Within the next three years we will all face “profound ethical decisions” about “what it means to be human”, bestselling novelist Dan Brown has warned.

The writer was speaking about one of the themes of his latest thriller starring Harvard professor Robert Langdon, which is expected to top this week’s bestseller list.

Brown, whose sales have already exceeded 200 million with his previous novels, told an audience of his fans at Freemason’s Hall in central London that he did not want to give away any of the plot of his latest page turner, Inferno, which was published a week ago.

Instead, he said he would talk about some of the topics of his latest offering, which sees Langdon in a number of Italian cities and other European locations, as he tries to stop the spread of a deadly virus due to a plot by famous geneticist Bertrand Zobrist to rebalance the world’s rapidly expanding population.

The novel, which takes inspiration from Dante’s Divine Comedy, sees Brown set out the case for population control (neo-eugenics), and he spoke of how the population of the planet has tripled in the past 85 years.

In the coming year, we will all face profound ethical decisions about emerging technologies and what it means to be human

One of the themes of the novel, he said, was the “rapidly growing philosophy called transhumanism or humanism+”, which explores the science and ethics of using advanced technology like genetic engineering to improve human physiology.

“Some scholars call transhumanism the most daring, courageous and imaginative aspiration of humanity,” Brown said.

“We now have the technology to manifest permanent genetic change in our species. We can create descendants of increased dexterity, stamina and even intelligence. The brain is a muscle, we have ways of making it more powerful.

“The question is should we? Is the next stage in human development where we start assisting our own evolutionary process? That we begin engineering ourselves? This is the debate that’s at the core of transhumanism.”

He went on: “According to some geneticists, the danger of playing God is that our genome is a house of cards, and if we try to alter a few human traits we have the potential of causing hundreds of others to shift unexpectedly to cause catastrophic events.

“Whichever side of the transhumanist debate you fall on, one thing is for certain: in the coming years – I’m not talking 20 years, I’m talking three years – we will all face profound ethical decisions about emerging technologies and what it means to be human.”

Brown, who became a household name with his 2003 bestselling novel The Da Vinci Code, unsurprisingly did not address the terrible reviews Inferno has had.

Despite his history of strong sales, his new adventure has once again come under fire for his literary abilities, with one reviewer calling it his worst book yet.

Although critics were in no doubt that readers would lap the book up, they were scathing about the writing on show.

Jake Kerridge in the Daily Telegraph said: “As a stylist, Brown gets better and better: where once he was abysmal, he is now just very poor.”

The Guardian said the book was “engineered with miraculous efficiency, a tasty cocktail of high culture and low thrills”.

Despite the poor reviews, Inferno jumped to the top of the bestsellers list this week with more than 200,000 copies sold.