In “Did Early Humans Ride the Waves to Australia?” (Wall Street Journal, February 4, 2012), Matt Ridley reports
For a long time, scientists had assumed a gradual expansion of African people through Sinai into both Europe and Asia. Then, bizarrely, it became clear from both genetics and archaeology that Europe was peopled later (after 40,000 years ago) than Australia (before 50,000 years ago).
Meanwhile, the geneticists were beginning to insist that many Africans and all non-Africans shared closely related DNA sequences that originated only after about 70,000-60,000 years ago in Africa. So a new idea was born, sometimes called the “beachcomber express,” in which the first ex-Africans were seashore dwellers who spread rapidly around the coast of the Indian Ocean, showing an unexpected skill at seafaring to reach Australia across a strait that was at least 40 miles wide. The fact that the long-isolated Andaman islanders have genes that diverged from other Asians about 60,000 years ago fits this notion of sudden seaside peopling.
Well, that makes more sense than the rodents who supposedly floated across the Atlantic on vegetation rafts or the crocodiles who crossed over from Egypt to the Caribbean just because they are strong swimmers.