Human aggression threatens to destroy Earth so we'd better start colonising planets soon, pioneering physicist Stephen Hawking has said.

"I believe that the long-term future of the human race must be space and that it represents an important life insurance for our future survival," said Hawking, speaking at London's Science Museum, "as it could prevent the disappearance of humanity by colonising other planets."

Hawking was addressing Californian visitor Adaeze Uyanwah who won a competition to receive a personal guided tour of the Science Museum by world famous physicist and writer.

He added: "Sending humans to the moon changed the future of the human race in ways that we don't yet understand. It hasn't solved any of our immediate problems on planet Earth, but it has given us new perspectives on them and caused us to look both outward and inward."

During the tour, Uyanwah asked Hawking what human trait he would most like to alter. He said: "The human failing I would most like to correct is aggression. It may have had survival advantage in caveman days, to get more food, territory, or reproduce, but now it threatens to destroy us all."

"A major nuclear war would be the end of civilization, and maybe the end of the human race," he said.

However, he concluded the tour on a more upbeat note, telling Uyanwah to hold on to a "childlike wonder" about what makes the universe exist. "Look up at the stars and not down at your feet," he said.

Hawking has previously warned that artificial intelligence also poses an existential threat to our survival. ®