Humans could have lived and thrived in inhospitable conditions in south Asia 20,000 years earlier than previously thought.
Research conducted on the Indonesian island of Sumatra showed signs of modern human life between 63,000 to 73,000 years ago and an ability to survive challenging rainforest conditions.
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Griffith University academic Julien Louyes said humans living in a rainforest was thought not to be possible until the last few thousand years.
"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," Dr Louyes said.
The study, published in the journal Nature, also revealed Homo sapiens may have completed the crossing from south Asia to Australia 10,000 to 15,000 years earlier than the popular theory of 50,000 years ago.
University of Queensland researcher Gilbert Price said the study was a follow-up on the work of paleoanthropologist Eugene Dubois conducted more than 100 years ago.
Professor Dubios and his team found two human teeth belonging to an early human dubbed the "Java-Man" while visiting the Sumatran caves in the late 1800s.
Dr Price and others revisited the site, which contained animal fossils in the same deposit as the human remains found by Professor Dubois.
Dr Louyes said the age of the animal fossils aligned with the dating of the rocks around the deposit, all of which supported the existence of modern humans in Sumatra as far back as 73,000 years ago.
"Because of how precious the human fossils are and given that dating methods are destructive, we weren't able to directly date the human teeth themselves," he said.
Griffith University professor Maxime Aubert said the findings may lead to new knowledge on the symbolic behaviour of modern humans.
"An interesting question is whether these early human colonisers exhibited manifestations of complex symbolic behaviour such as cave paintings," Professor Aubert said.
The findings follow a breakthrough in the Northern Territory, where excavated artefacts confirmed the presence of Aborigines in Australia as far back as 65,000 years - 18,000 years earlier than previous estimates.