科学美国人60秒:Human Remains Double Known Rainforest Occupation Time

People have been living near rainforests for tens of thousands of years, but most available evidence has intense use of forest resources starting just 10,000 years ago. So scientists thought that the dense, tropical forests were so hard to navigate and find food in that humans would have mainly depended on open plains nearby.

But some researchers had doubts. Modern forest foragers do just fine in the rainforest. And some evidence in Africa pointed to humans in rainforests well before the 10,000 year mark.

Now there’s hard evidence, out of Sri Lanka, that people roamed and dined on rainforest offerings at least 10,000 years earlier than we’d thought. The finding is in the journal Science. [Patrick Roberts et al, Direct evidence for human reliance on rainforest resources in late Pleistocene Sri Lanka]

Researchers measured carbon and oxygen isotopes in the remains of 26 humans found in the Sri Lankan rainforest. The bodies were some 20,000 years old.

Isotope signatures differ for plants that live beneath the closed rainforest canopy than for plants from the open plains. Any animals that eat those plants then also carry those forest isotopes—as did the remains, showing that these humans subsisted on tropical forest vegetation.

The findings show that humans have been taking advantage of rainforests for at least 20 millennia. Whether our accelerated resource extraction will allow any substantial rainforests to exist even one thousand years from now is a very open question.

—Cynthia Graber