A publication of the Archaeological Institute of America
New dates from two sites on the Indonesian island of Flores prove that Homo erectus was able to navigate open waters between 800,000 and 900,000 years ago. Previously, modern humans who colonized Australia were credited with the earliest sea crossings, 40,000 to 60,000 years ago.
Michael J. Morwood of Australia's University of New England and his colleagues presented their conclusions, based on excavations at Tangi Talo and Mata Menge, in the journal Nature. Tangi Talo yielded the remains of pygmy stegodon (a type of elephant), giant tortoise, and Komodo dragons, but no tools. Mata Menge, however, produced a small number of stone tools, including some made of nonlocal chert, as well as remains of large stegodon, crocodile, giant rat, freshwater molluscs, and plants.
Morwood dated the sites using a technique that analyzes individual zircon crystals from volcanic deposits. A sample from Tangi Talo, taken near a pygmy stegodon tusk and giant tortoise shell fragments, yielded a date of about 900,000 years ago. At Mata Menge, a sample from just beneath the artifact-bearing level dated to about 880,000 years ago, while another, taken above in situ artifacts, gave a date of about 800,000. The sites' early dates and the identification of the stone tools seem secure, according to Carl Swisher of the Berkeley Geochronology Lab.
Tools this early in Southeast Asia can only have been made by Homo erectus. Unlike Java, which was periodically connected to mainland Asia and accessible to early humans on foot, Flores could be reached only by crossing an 11.4-mile-wide strait, even at times of lowest sea level. The Mata Menge artifacts prove that H. erectus was able to make the crossing.
The new dates also support the suggestion made by Dutch paleontologist Paul Sondaar more than a decade ago that the extinction of pygmy stegodon on Flores ca. 900,000 years ago was the result of human predation.