Investigating pre-modern colonisation of the Indian Ocean: The Remote Islands Enigma

Island colonization worldwide began in the Indian Ocean when groups of Homo erectus from Java reached Flores, and probably Timor, nearly a million years ago. The first substantial sea crossing by Homo sapiens was to Australia some fifty to sixty thousand years ago, and long-distance offshore sailing began about 2000 BCE in the northern Indian Ocean, earlier than in the Pacific or Atlantic. The Indian Ocean has some claim, then, to being “by far the oldest of the seas of history.” But therein lies an enigma: By the early second millennium CE, nearly all of the habitable islands in the Atlantic and Pacific Oceans had been colonized by indigenous seafarers, yet discovery and settlement of many Indian Ocean islands does not seem to have occurred until after the arrival of European shipping, beginning around 1500 CE. An interocean comparison illustrates the difference. The habitable Indian Ocean is a fifth the size of the habitable Pacific, but the occurrence of islands is comparable: about eight and ten per 1,000,000 square kilometers (km2) of ocean, respectively. However, while only 2.5 percent of islands in the habitable Pacific were unoccupied by 1500 CE, the comparable figure was 28 percent in the Indian Ocean...