By Eva Botkin-Kowacki
When early humans began trekking out of Africa, they spread across Eurasia on foot. As some made it down into then-peninsular Southeast Asia, they would have run into a watery boundary, called Wallace’s Line, that scientists thought essentially uncrossable by animals until around 50,000 years ago, when Homo sapiens arrived with boat technology.
But somehow another human species had crossed into that island region, called Wallacea, long before H. sapiens even reached Southeast Asia. In 2004, archaeologists discovered fossils of an archaic human, H. floresiensis, nicknamed “Hobbit” for its stature, on the island of Flores, Indonesia.
Now, research reveals Flores may not have been the only human-populated island in the region at the time. Scientists recently unearthed stone tools on the neighboring island of Sulawesi that date to between 118,000 and 194,000 years ago.
“Our findings suggest that Sulawesi, like Flores, was host to a long-established population of archaic hominins,” the researchers write in their paper published Wednesday in the journal Nature.
The humans living on these Indonesian islands “might have been much more common than we have realized so far,” study lead author Gerrit van den Bergh tells The Christian Science Monitor in an interview.
But, unlike on Flores, “We don’t know yet the identity of the toolmaker,” Dr. van den Bergh says.
These ancient Sulawesi residents may have been members of the species H. erectus, who are known to have lived in nearby Java some 1.5 million years ago, or perhaps they were their relatives.
Archaic humans in Java are no huge surprise, as sea levels were likely low enough to connect the island to mainland Southeast Asia at the time. But Flores and Sulawesi would have been isolated islands past Wallace’s Line. So when H. floresiensis was discovered, scientists began to ponder the dispersal of humans throughout Wallacea.
These early Sulawesi residents might be a piece of that puzzle. “Sulawesi is a big land mass” quite nearby Flores, paleoanthropologist Russell L. Ciochon from the University of Iowa in Iowa City, who was not affiliated with the study, tells the Monitor in an interview. “So I assumed that humans got there, but we didn’t have any firmly dated evidence.”
“This provides the data. Now we can build the colonization of Sulawesi into our models,” says Dr. Ciochon, who researches H. erectus in Java.
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