A small number of early humans clinging to floating debris could have accounted for some island settlement in human prehistory, they said.
Using population estimates from the early settlement of Polynesia, researchers from Liverpool John Moores University and the University of St. Andrews estimated five young couples washed up on an island would have a 40 per cent chance of giving rise to a population of 500, a population that could survive for 500 years.
Ten random castaways not evenly divided between male and female would have only a 20 percent chance, but the arrival of between one and four additional castaways every 50 years raised the chances of an accidental settlement succeeding to 47 percent, the researchers said.
Stone tools show hominins -- possibly Homo erectus -- reached the Indonesian island of Flores 1 million years ago.
Previous studies have shown other mammals managed the feat. Rats and Stegodon, an extinct relative of the elephant, have crossed the deep-water channel between the Indonesian islands of Java and Flores, NewScientist.com reported.
Elephants are strong swimmers, and rats could have traveled on storm debris, researchers said.