Stone tools and plant remains indicate that, as early as 49,000 years ago, people lived 2,000 meters, or 1.2 miles, above sea level in Papua New Guinea’s Ivane Valley, say archaeologist Glenn Summerhayes of the University of Otago in Dunedin, New Zealand, and his colleagues.
By at least 50,000 years ago, modern humans occupied lowland rainforests and savannas of southeastern Asia’s land mass known as Sunda. From there they crossed the open ocean to Sahul, presumably in seacraft of some kind. Rising sea levels separated Papua New Guinea from Australia roughly 10,000 years ago.
Many researchers assume that modern humans spread from Africa to Sahul along the coast and preferred living at low altitudes. That idea gets drubbed by the new discoveries, Summerhayes says. Shortly after reaching Sahul’s shores, settlers headed uphill to the Ivane Valley’s thin air, cold temperatures and harsh habitat, the scientists conclude in the Oct. 1 Science.