Scientists have adopted a novel technique using wasp nests to estimate the age of previously undateable rock art, called Gwions, in the Kimberly region of Western Australia.
The results appear to confirm the artists responsible for the work lived during a time of rising sea levels and social disruption, when many were forced to abandon their settlements for locations further inland. These markings, the researchers suggest, could symbolize attempts by early environmental refugees to "make a place their own—a home."
Gwions, ancient artworks created by local aborigines, have mystified archeologists for years. While many remain in a state of remarkable preservation, the reddish ochre pigments lack organic material that can be carbon-dated.
"One of the best known styles showing human figures with complex headdress and body ornaments is the Gwion Gwion," Professor Peter Veth, Director of the University of Western Australia's (UWA) Oceans Institute said in a statement.
"Formerly known as 'Bradshaws,' their extraordinary detail challenged European observers and led to more than a century of speculation about their age and authorship."
Enter wasp nests. Veth and others at UWA adopted a technique used to indirectly date the artwork. Instead of carbon dating the images themselves, they carbon dated tiny flecks of charcoal in mud nests made by mud wasps that both overlay and underlay the rock art.
These flecks would have been unintentionally deposited by wasps while making the nest however many thousands of years ago.
For a study published in Science, the team dated 21 human-like Gwion figures using 24 nests, some of which overlayed the pigment. This means they were made after the Gwion and provide a minimum age. Others underlay the pigment, meaning they were made before the Gwion and provide a maximum age.
The researchers suppose that were the Gwion motifs produced over an extended period of time lasting thousands of years, there would be significant overlap in the ages of mud nests overlaying and underlying the art. In contrast, the results of the study suggest they were painted within a relatively short timeframe.
The dates calculated through the mud nests suggest the vast majority of Gwions were created approximately 12,000 years ago. There was one notable exception, they say. A single motif was dated to a time approximately 17,000 years ago.
These findings places the Gwions in the Pleistocene era, between 2.6 million to 11,700 years ago.
Gwions frequently depict human-like figures in elaborate dress, often holding spears, boomerangs and other ornaments.
"[The rock art] is a codified set of relationships, behaviors and aspirations in visual form," co-author Sven Ouzman, archeologist and Associate Professor at the University of Western Australia, told Newsweek. "[It] is firmly emplaced, so it offers people a way to stabilize their attachment to a place, whether they are moving into a new area or are people hosting incomers."
The dating of the rock art puts its creation firmly within a period of time when sea levels around the Australian continent were rapidly rising.
Approximately 800,000 square miles (2.12 million square kilometers) of land was lost from Australia within a 17,000-year timespan between 35,000 and 8,000 years ago. During that time, coastlines moved 86 miles or so (139 kilometers) in land at rates of up to 23.7 meters per year, according to a study published in Quaternary Science Reviews.
This caused severe disruptions to the people who lived there, despite the relatively sparse populations that inhabited Australia at the time.
"As the plant warmed after the Last Glacial Maximum, ocean levels rose, inundating land and forcing people to move inland," said Ouzman. "This inland may have been populated by other groups, causing social dislocation."
The bulk of land lost—approximately 90 percent, said Ouzman—occurred within a relatively tight timeframe between 14,600 and 8,000 years ago. This forced people to abandon homes and their way of life.
The period was so disruptive that tales of sea level rise has passed from generation to generation of indigenous communities for 7,000 plus years—a display of "extraordinary longevity" in terms of oral storytelling that is unparalleled elsewhere on the planet. This is not just a one-off. Thousands-year old stories have been presented from 21 locations.
"Rock art is not a passive reflection of the world but an active means to manage it," said Ouzman
"Gwions appear to be very anthropocentric, with a lot of rich material culture and accoutrements that may be linked to ceremony," he added. "But also to allow people to mark and make a place their own—a home."
"Linking dated rock art to ocean level changes, palaeoenvironmental data and excavated archaeology helps us to begin to understand how this incredibly adaptable group of people survived—and thrived—in one of the world's most environmentally dynamic regions."
"In sum, people were severely disrupted, but reconfigured themselves with rock art playing a key role in signaling this new identity and, at times, solidarity."