Dated rock painting through wasp nests

This picture of a kangaroo was made in northwest Australia over 17,000 years ago. (Image: Illustration: Pauline Heaney)

Researchers have identified a two-meter-tall kangaroo figure in the Kimberley region as the oldest known figurative rock painting in Australia. The picture was taken over 17,000 years ago and is the result of its unusual dating method: the relics of old wasp nests above and below the layer of the image enabled indirect radiocarbon dating. Research results from other animal images in the region showed that depictions in the style of the kangaroo had been made there for over 4000 years.

Impressive traces of creativity: in many places around the world, people immortalized themselves in rock paintings in the distant past. Animal representations are a common motif. How old these works are, however, is often difficult to determine, as there is often no organic material in the color pigments that is suitable for direct radiocarbon dating. The previous record dating is the result of a uranium isotope analysis of lime deposits on rock paintings on the island of Sulawesi, which revealed an age of over 40,000 years. In Australia, studies of finds in connection with rock art also indicate an age of 28,000 years or even 40,000 years. But in both cases the findings cannot be clearly assigned to painted rock paintings.

With the clearly recognizable figurative rock paintings of the ancestors of the Australian Aborigines, researchers have so far only been able to show which forms of representation are the oldest based on the sequence of overlaying images. These were images of animals in a naturalistic style: They were shown in a characteristic way in their natural life size. How old these works are, however, has not yet been determined. The scientists working with Damien Finch from the University of Melbourne have now succeeded in using radiocarbon dating to determine the age.

Dating through wasp nests

This was possible in an indirect way: the researchers used the organic material in the traces of fossil wasp nests on the rock faces of the sites. These are the nests of so-called mud wasps – they build small, resistant nests on hard surfaces from mixtures of substances. As the researchers explain, the prehistoric artists painted over these structures and then the wasps often rebuilt nests on the works. “A picture under a wasp’s nest must therefore be older than the nest, and a painting over a nest must be younger than this structure,” said Finch. “In this way, conclusions can be drawn about the time window in which the rock painting was created,” says the scientist.

The current study focused on rock paintings from eight sites in the Kimberley region in northwest Australia. The outstanding finding comes from a picture in the area of ​​the Unghango Aborigines in the Balanggarra country above the Drysdale River. It is a two-meter-tall representation of a kangaroo in the typical style of the earliest period, the researchers explain. They were pleased to see that both above and below the figure there are remains of several mud wasp nests that are suitable for sampling for radiocarbon dating.

Painted over 17,000 years ago

“We have three wasp nests that are under the painting and three are dated on top,” says Finch. “So we came to the conclusion that the work is between 17,500 and 17,100 years old – most likely 17,300 years,” said the scientist. This dating result now makes the kangaroo the “oldest radiometrically dated in situ rock painting in Australia”, the researchers write. By dating the wasp nests of other animal representations – including a snake, a lizard-like figure and marsupials, they were also able to show that the paintings in the naturalistic style were common in Australia at least from 17,000 to 13,000 years ago.

“These are important findings as they provide clues about the world in which these early artists lived. We can’t know what people were thinking when they painted these works up to more than 600 generations ago, but we now know that the naturalistic period went back to the last Ice Age, ”says Finch. It is known that the environment was cooler and drier back then and the sea level was lower, so that today there are no land connections.

Co-author Sven Ouzman from the University of Western Australia in Crawley sees the results as an important contribution to understanding the cultural history of the indigenous people of Australia. “This iconic kangaroo image is visually similar to rock art from islands in Southeast Asia that is more than 40,000 years old, suggesting a cultural connection – and suggesting that even older rock art exist in Australia,” says Ouzman.

The scientists now want to continue using wasp nests for dating in order to gain more insight into the cultural development history of the early Australians. Among other things, they want to clarify when certain periods of art in the rock art of these people began and ended.

Source: University of Melbourne, specialist article: Nature Human Behavior, doi: 10.1038 / s41562-020-01041-0

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