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Humans Survived in the Indonesian Rainforest 70,000 Years Ago

New evidence published in Nature not only suggests that modern humans were present in South-East Asia 20,000 years earlier than previously thought but that they managed to inhabit rainforests – a concept not thought possible for early humans.

The possibility that humans were in South-East Asia 73–63,000 years ago means they could have potentially made the crossing to the Australian continent even earlier than 50,000 years ago. This is consistent with another recent Nature paper that documented cultural artefacts 65,000 years ago in a rock shelter in northern Australia (http://tinyurl.com/ycxt5tvl). There is also temporal overlap of modern humans and the more ancient “hobbit” fossils found on Flores a couple of islands away.

Griffith University researchers were part of a team that used a combination of methods to date the Lida Ajer cave site in western Sumatra, which contains fossils of rainforest fauna associated with two human teeth. Until now, the significance and validity of the remains had not been widely accepted.

The presence of modern humans in Sumatra up to 73,000 years ago occurred when the region was dominated by a closed canopy rainforest ecosystem similar to today. “Successful exploitation of rainforest environments is difficult, and requires the capacity for complex planning and technological innovations to secure adequate resources,” said Dr Julien Louys of the Australian Research Centre for Human Evolution at Griffith University.

“Living in a rainforest was not thought to be possible until only the last few thousand years because sourcing enough carbohydrates and proteins in dense canopy forests requires sophisticated hunting technology and knowledge that the first humans out of Africa would not have possessed. Our study indicates that such innovations and capacities were in place in Asia by at least 60,000 years ago.”

A/Prof Tanya Smith performed microCT scans on the teeth to distinguish them from orang-utans. “When you look at the inside of the teeth, the characteristics of the enamel are quite different, and we couldn’t be sure whether the molar was from an orang-utan or a human from the outside,” she said.

A/Prof Maxime Aubert of the Griffith Centre for Social and Cultural Research (GCSCR), who dated the hobbit fossils as well as some of the world’s earliest cave art in Sulawesi, used the same technique to date the teeth of fauna found in association with the human teeth. “Now that we have established that modern humans were present in South-East Asia 20,000 years earlier than previously thought, an interesting question is whether these early human colonisers exhibited manifestations of complex symbolic behaviour such as cave paintings,” he said.