From ScienceDaily:
While it is accepted that humans appeared in Africa some 200,000 years ago, scientists in recent years have placed the approximate date of human settlement in Australia further and further back in time, as part of ongoing questions about the timing, the routes and the means of migration out of Africa.
Now, a team of researchers, including a faculty member and seven students from the University of Washington, has found and dated artifacts in northern Australia that indicate humans arrived there about 65,000 years ago — more than 10,000 years earlier than previously thought. A paper published July 20 in the journal Nature describes dating techniques and artifact finds at Madjedbebe, a longtime site of archaeological research, that could inform other theories about the emergence of early humans and their coexistence with wildlife on the Australian continent.
The new date makes a difference, co-author and UW associate professor of anthropology Ben Marwick said. Against the backdrop of theories that place humans in Australia anywhere between 47,000 and 60,000 years ago, the concept of earlier settlement calls into question the argument that humans caused the extinction of unique megafauna such as giant kangaroos, wombats and tortoises more than 45,000 years ago.
“Previously it was thought that humans arrived and hunted them out or disturbed their habits, leading to extinction, but these dates confirm that people arrived so far before that they wouldn’t be the central cause of the death of megafauna,” Marwick said. “It shifts the idea of humans charging into the landscape and killing off the megafauna. It moves toward a vision of humans moving in and coexisting, which is quite a different view of human evolution.”
…
Noteworthy among the artifacts found were ochre “crayons” and other pigments, what are believed to be the world’s oldest edge-ground hatchets, and evidence that these early humans ground seeds and processed plants. The pigments indicate the use of paint for symbolic and artistic expression, while the tools may have been used to cut bark or food from trees.Paper. (paywall) – Chris Clarkson, Zenobia Jacobs, Ben Marwick, Richard Fullagar, Lynley Wallis, Mike Smith, Richard G. Roberts, Elspeth Hayes, Kelsey Lowe, Xavier Carah, S. Anna Florin, Jessica McNeil, Delyth Cox, Lee J. Arnold, Quan Hua, Jillian Huntley, Helen E. A. Brand, Tiina Manne, Andrew Fairbairn, James Shulmeister, Lindsey Lyle, Makiah Salinas, Mara Page, Kate Connell, Gayoung Park, Kasih Norman, Tessa Murphy, Colin Pardoe. Human occupation of northern Australia by 65,000 years ago. Nature, 2017; 547 (7663): 306 DOI: 10.1038/nature22968 More.
It’s possible that the environment was changing such that life was bad all over for megafauna. That is, being BIG wasn’t such an asset any more.
Which doesn’t mean humans had no impact on numbers. Most likely, going extinct is due to a variety of bad luck factors operating at once, so that there is not enough time for a life form to adapt to serial complex changes.
Also, from Alice Klein at New Scientist First Australians may have arrived much earlier than we thought:
This is an evolving picture, though. For instance, there is some evidence that H. sapiens reached a more northerly island of South-East Asia – Luzon in the Philippines – 67,000 years ago.
O’Connor is also puzzled by the early humans’ wanderlust. Sea levels were substantially lower 65,000 years ago, making it easier to move between Asia, Australia and the islands en route. But humans still had to cross open water stretching for 80 kilometres to make it to mainland Australia, she says. “There’s no obvious reason like climate shifts to explain the rapid movement.” More.
Hmmm. Paging Thor Heyerdahl (1914–2002).
See also: Researchers suggest: Life began on land, not sea. And nearly 600 mya earlier than thought