By Belinda Smith and Erin Parke, ABC Science, February 22, 2021Traditional owner Ian Waina inspecting a painting of a kangaroo that is at least 12,300 years old, based on the age of wasp nests over the paint.
As far as Australian icons go, it's hard to look past the kangaroo. Now it turns out the quintessential macropod is also the subject of Australia's oldest-known rock painting.
The 17,300-year-old roo, portrayed in dark mulberry paint on the ceiling of a rock shelter in the Kimberley, is one of a suite of animal depictions — and the odd human-like figure — unveiled in Nature Human Behaviour today.
Traditional owners and archaeologists worked together to calculate the age of "naturalistic" rock art, in Drysdale River National Park, painted by ancestors of the Balanggarra people.
To do this, the researchers dated not the artwork itself, but fossilised mud nests built by industrious wasps all those years ago.
And while traditional owners have known about these paintings, no-one knew how old they were.
Ian Waina, traditional owner and Kwini man, said visitors and locals alike are keen to hear how old the paintings are.
"It's something that all tribes want to know — how old are our paintings?" Mr Waina said.
"And tourists always ask too, but many Aboriginal people have had no idea.
"What we've done now with the scientists is open up the gate to find out."
A rich tradition of rock art
The Kimberley is renowned for its rich rock art galleries.
The naturalistic style analysed in this paper is one of the oldest of at least six distinct phases of paintings documented in the region.
It is older than dynamic figures with elaborate headdresses known as Gwion figures, examples of which were recently dated to be about 12,000 years old.
Peter Veth, an archaeologist at the University of Western Australia who was part of the rock art dating project, said the style shift reflected social changes in the region, at what is now the very top tip of Western Australia, in the face of a changing climate.
"That art, those pigments, those markings are fixed in the sandstone, they're surviving from the Pleistocene, from before 12,000 years ago," Professor Veth said.
Supplied: Pauline Heaney And Damien Finch
)Why wasps?
Dating rock art is notoriously difficult. Archaeologists can piece together a rough order of different styles in shelters where artists have painted over existing art, but nailing precise ages is a challenge researchers have grappled with for decades.
The paint, while rich in iron — and which imparts that distinctive wine-red hue — doesn't contain enough chemical elements, like carbon, to analyse with current dating techniques.
So scientists had to look elsewhere. But not too far.
Those rock shelters weren't only used by humans over the millennia. The cool, protected areas were ideal wasp nurseries. Rock walls and ceilings could be studded with hundreds — or even thousands — of mud wasp nests.
As time wore on, some of the hardy little mud pods fossilised. Sometimes, they were painted over.
Other times, wasps constructed fresh nests on artworks, which fossilised on top of the paint.
Damien Finch, a PhD student at the University of Melbourne and lead author of the new paper, and colleagues believed if you could calculate the age of mud wasp nests lying over and under a painting, you could feasibly calculate an age range for that artwork.
Mr Finch's team was not the first to enlist the help of mud wasp nests to date rock art in Australia.
In the late 1990s, a different Australian team dated wasp nests atop a Kimberley painting to 16,400 years old.
The technique, called optically stimulated luminescence, measured the time since quartz grains in the nest were last exposed to sunlight.
But it had its limits. For instance, it needed large nests to ensure quartz grains were completely shielded from light.
Supplied: Sven Ouzman, Balanggarra Aboriginal Corporation
)To find out if mud wasp nests contained carbon for radiocarbon dating, Mr Finch and his crew visited the Kimberley in the wet season, where they watched mother wasps collecting balls of mud, flying it to a shelter and diligently packing it on rock surface into a nest.
Mr Finch found carbon was, indeed, present in the mud: some in pollen and other bits of plants, but most was contained in little chunks of charcoal.
"Of all the carbon-bearing sources that are in the nest when it's built, the thing that's likely to survive the longest is basically charcoal," Mr Finch said.
"There's so much charcoal in the Kimberley environment and across northern Australia, because about a third of the Kimberley burns each year."
Ancient charcoal extracted from the nests
As the nests age, they become incredibly hard, sealing the precious charcoal inside.
Collecting them, Mr Finch said, is like chipping off a piece of rock.
During the three sample-collection trips in 2015, 2016 and 2017, as part of the Rock Art Australia project, the team used small chisels like dentists might use to knock off small amounts of wasp nest material.
Working with the traditional owners, the archaeologists carefully selected which areas to take samples from, making sure there was as little disruption to the artwork as possible.
Mr Waina, who accompanied the archaeologists on their trips to the rock art sites, said the traditional owners were happy to give permission for Mr Finch and his team to study these sites.
Wasp nests in hand, the next step was to extract that ancient charcoal and date it.
The team first used the technique to date the Gwion figures in a rock shelter on Balanggarra country.
The latest paper shows the naturalistic style paintings were painted around 17,000 and 13,000 years ago — maybe even earlier.
And one — the kangaroo daubed on a rock shelter ceiling — had wasp nests above and below the paint.
It was dated to between 17,500 and 17,100 years ago, making it the oldest-known painted figure in Australia.
Supplied: Photos: Damien Finch Illustration: Pauline Heaney
)Similar style to older art elsewhere
Adam Brumm, an archaeologist at Griffith University who was not involved in the study, said finally putting dates on Kimberley naturalistic paintings was "really exciting".
"This particular style of animal paintings has been known about for quite a while, but it's the dating of it that has been pretty uncertain," he said.
Earlier this year, Professor Brumm was part of a team that dated rock art of a similar style from the Indonesian island of Sulawesi.
But instead of carbon-dating mud wasp nests, they used uranium dating techniques on "cave popcorn" — hardened layers of minerals that formed when water dribbled down the rock face and over the paintings.
From these, they calculated that one animal, a warty pig, was at least 45,500 years old.
The Sulawesi style is similar to the naturalistic Kimberley art: animals, often shown in profile, with a rounded body filled with lines and solid-coloured limbs.
But the Sulawesi paintings and those analysed in Mr Finch's paper are separated by about 30,000 years. So how can that be?
Supplied: Damien Finch
)While these examples of rock art in Indonesia and Australia may look, at first glance, very similar, new research suggests there are subtle but important variations within that style.
"It could be that this is not one single style that only lasted a few thousand years, but a conglomeration of many different styles that have artificially been grouped by us into a single one," Professor Brumm said.
"I think a lot more work needs to be done to figure out what the connections are with what seem to be superficially similar styles of rock art and other parts of the world, including in Sulawesi. It's too hard to say yet if there's a direct connection between them."
Mr Finch agreed more research is needed to uncover any links — if they existed — between similar art sites.
But he also pointed out that some styles of art are seen the world over in many different periods of human habitation.
Take hand stencils, for instance: "We see hand stencils everywhere. It's a basic sort of art form: to put your hand up on the wall, and with your mouth full of pigment, spray a hand outline.
"I guess if a particular animal is really important to you, because maybe it's a food source, then perhaps it is something that you choose to paint."
Upheaval at the time
Estimating an age range for the naturalistic style of rock art "is an amazing window" into how Kimberley cultures formed, Professor Veth said.
"Art is a window into what they thought was important about their own groups, about each other, about presumably their totemic geography, about their religious frameworks."
The sites where the paintings reside today are less than 100 kilometres from the coast. But it wasn't always this way.
When the kangaroo was painted 17,000 years ago, the planet was in the grip of the Last Glacial Period.
At the time, huge volumes of seawater were locked away in giant ice sheets, and sea levels were more than 100 metres lower than they are today.
"[During] the Last Glacial Period in Australia, the coast would have been three to 400 kilometres from these dated sites, conditions would have been much more arid," Professor Veth said.
When the ice sheets melted, sea levels rose. Weather conditions such as monsoon patterns shifted and huge swathes of the area's coastal plain — perhaps a million square kilometres — were lost.
Supplied: Damien Finch And Pauline Heaney
)That's also when Kimberley art shifted from the naturalistic style (during what archaeologists call the "irregular infill animal period"), which focused on the natural world, to the people-centred Gwion style, Professor Veth said.
"Gwion figures show social groups, ceremonial groups, incredibly elaborate human figures.
"And so the gaze is almost shifting from the environment and the landscape in a big open social networking sense, to a much closer focus on new territories, social groupings and people's performances."
Climate upheaval is reflected in ancient art around the world, he added.
"I find it fascinating that that is part of a global trend … where global populations are responding and reconfiguring in response to a changing world."
Mr Finch said dating more paintings in the naturalistic style is sure to yield ones older than the kangaroo.
"These are the first dates on paintings in that style that have been published. There haven't been any others," he said.
He's not alone. Mr Waina suspects older rock art is out there too, just waiting to be dated.
"I just want to try find out more, and see if we can find the real oldest, because I know for a fact that animal infill [style] is very old, it's more old than … the Gwion.
"So I just hope we find more paintings like that too."
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