The painted outline of a human hand inside a cave on the Indonesian island of Muna represents what researchers are calling the oldest example of rock art in the world, created at least 67,800 years ago.

The reddish-colored stenciled image has become faded over time and is barely visible on a cave wall, but nonetheless embodies an early achievement of human creativity as our species spread worldwide after arising in Africa. The people responsible for this rock art, the researchers said, were part of a population that made its way from mainland Asia to the islands of Indonesia, and later may have continued on to Australia.

The hand stencil was discovered in a limestone cave called Liang Metanduno on Muna, a satellite island off the southeastern peninsula of the large island of Sulawesi east of Borneo. The researchers determined the minimum age of the image by analyzing small amounts of the element uranium in mineral layers that gradually formed atop the pigment.

The image and others like it that were discovered were made by blowing pigment over a hand placed against the rock wall, the researchers said.

"The oldest hand stencil described here is distinctive because it belongs to a style found only in Sulawesi. The tips of the fingers were carefully reshaped to make them appear pointed," said Maxime Aubert, a specialist in archaeological science at Griffith University in Australia who helped lead the research published on Wednesday in the journal Nature.

"It was almost as if they were deliberately trying to transform this image of a human hand into something else - an animal claw perhaps. Clearly they had some deeper cultural meaning but we don't know what that was. I suspect it was something to do with these ancient peoples' complex symbolic relationship with the animal world," said Griffith University archaeologist and study co-author Adam Brumm.

The hand stencil is older than a cave painting depicting three human-like figures interacting with a pig dated to at least 51,200 years ago at the Leang Karampuang site in southwestern Sulawesi. It also is older than rock art in the form of a hand stencil at Maltravieso in Spain that dates to around 64,000 years ago and has been attributed to Neanderthals.

While the newly described image was barely discernible, the researchers found nearly identical images in much better shape elsewhere in the area, showing that this design was not a one-time creation. In earlier research in Sulawesi, the researchers also documented images of human figures with animal features, dated to at least 48,000 years ago.

The researchers said the Liang Metanduno cave is a tourist site, usually visited for its large and more recent paintings. Those are attributed to Austronesian-speaking farmers who first appeared in the region around 4,000 years ago.

The scientists said their discovery of the age of the Liang Metanduno hand stencil may provide insight into how and when Australia came to be settled by Homo sapiens. They said it is probable that the people who fashioned this artwork at Liang Metanduno and around Sulawesi were part of a broader population that later would spread through the region and eventually reach Australia.

"For many years, scientists have debated when and how the first people reached Australia. One idea is called the 'short chronology.' This suggests that people arrived in Australia around 50,000 years ago. This view was supported by many archaeological sites across Australia dated to this time. Earlier genetic studies of Aboriginal Australian and Papuans' DNA also appeared to fit this later arrival," Aubert said.

"Another idea is the 'long chronology,' which proposes that people reached Australia much earlier, around 60,000 to 65,000 years ago," Aubert said.

The newly dated rock art provides the oldest direct evidence of modern humans in the region. And recent genetic research lent support to an earlier arrival time in Australia, closer to 60,000 years ago, Aubert said.

"Together, the archaeological and genetic evidence now strongly supports the 'long chronology' and shows that the ancestors of Indigenous Australians were moving through Southeast Asia and creating symbolic art as they traveled," Aubert said.