The scientist died in March but left a collection of articles which outlined his concerns about the future of the human race. In his final book In Brief Answers to the Big Questions, out on Tuesday, Professor Hawking states that he fears wealthy people will begin to edit their own and their children's DNA to create 'superhumans' who will be more intelligent and live longer.

He wrote: 'Once superhumans appear, there will be significant political problems with unimproved humans who will be unable to compete.

'Presumably, they will die out, or become unimportant. Instead there will be a race of self-designing beings who are improving at an ever-increasing rate.' He predicted that even if laws were passed to kerb genetic engineering there would always be people prepared to break any rules which would spark the rise of superhumans.