"Instead, there will be a race of self-designing beings who are improving at an ever-increasing rate", noted the scientist, who suffered from motor neurone disease that had left him nearly completely paralysed for most of his life. "But some people won't be able to resist the temptation to improve human characteristics, such as memory, resistance to disease and length of life", Hawking wrote.
His book now reveals that according to Hawking, there is no afterlife or supreme being.
Hawking says the human race had to improve its mental and physical qualities, but a genetically-modified race of superhumans, say with greater memory and disease resistance, would imperil the others.
According to the excerpt, which was earlier reported on by the Washington Post, Hawking wrote that he believes people-and especially the wealthy-could alter human genes to create people who are extremely intelligent or even aggressive.
In the early stages of these daunting capabilities - enabled by gene-editing technologies like CRISPR - Hawking suggests genetic changes "will be confined to the fix of genetic defects". They also said the technique could be used to enhance certain traits.
One of the world's most prominent physicists, the late Stephen Hawking, was the first scientist to set out a theory of cosmology based on a combination of the general theory of relativity and quantum mechanics.
'The present world order has a future but it will be a very different one'.
Professor Stephen Hawking Physics at Cambridge University in 1988.
Although Hawking was known for his work on cosmology and black holes, his final book is a "reflection of his humanity" and his hopes that risky new technologies could not just destroy, but also unite and revolutionise human life.
"The real risk with AI isn't malice, but competence".
But if he were he would be speaking out not just on the exotic problems of fundamental physics and cosmology.
While Hawking's views on this topic could be considered somewhat alarmist, scientists have been debating the ethics of CRISPR for years, with many sharing fears of how the genetic modifications could lead to things like 'designer babies.'
"AI could develop a will of its own, a will that is in conflict with ours and which could destroy us". "We stand on a threshold of a fearless new world".