Cave of Lubang Jeriji Saleh,
Prehistoric art, Borneo: 38,000 BC
This collection of prehistoric art remains largely untouched and undated, but the sites examined so far - such as Lubang Jeriji Saléh cave on the Sangkulirang-Mangkalihat Peninsula - have produced examples of parietal art dating back as far as 38,000 BC.
This is only slightly younger than the Sulawesi Cave paintings recovered from the caves and shelters of Maros-Pangkep across the Makassar Strait.
The finds in Kalimantan and Sulawesi have already rewritten the narrative of cave painting, and established SE Asia as an independent centre of paleolithic art, several thousand years before Europe.
In addition, they raise hopes that aboriginal rock art in Australia will prove to be much older than results so far suggest.
It's worth noting that Java - Kalimantan's immediate neighbour to the south - is the site of the world's oldest art - the Trinil Shell Engravings, dating to between 540,000 BC and 430,000 BC.
Local inhabitants have known about East Kalimantan's cave paintings for years.
But it was only in the 1990s, when Indonesian and French archaeologists investigated the decorated cavities in the densely forested peaks of the Sangkulirang-Mangkalihat Peninsula, that some of the murals were documented and dated.
Interestingly, archaeologists found no traces of human occupation in the painted caves, a situation similar to several sites in Europe, such as Chauvet Cave in France.
It seems the caves were used only to create art - viewed later perhaps at ceremonial gatherings.
Following the initial series of investigations, a French-Indonesian team led by Maxime Aubert returned to the caves to obtain new test samples, and to retest the paintings by using the same dating method on different patches of paintwork.
The dating method used by Aubert and his team to fix the minimum age of the cave paintings in East Kalimantan, was to date the calcium carbonate overlying the paintings, using the uranium-thorium (U-Th) method.
The U-Th method is based on the isotope activity ratios of the parent (Uranium) and daughter (Thorium). Put simply, the more thorium, the older the calcite.
Over the past fifteen years, there has been a lot of debate among archaeologists over which method is best to date ancient cave art: radiocarbon or U-Th dating.
Radiocarbon dating can only be used on organic (as opposed to mineral) pigments, and at the moment can't be used to date samples more than 50,000 years old.
In contrast, U-Th can be used to date any type of colouring material, and is effective up to 450,000 years.
Researchers dated samples of calcium carbonate overlying paintings at six caves on the Sangkulirang-Mangkalihat Peninsula in East Kalimantan.
They included the caves of: Lubang Jeriji Saleh, Lubang Ham, Liang Karim and Liang Tewet, as well as the more easterly Liang Sara and Liang Banteng.
Kalimantan's oldest parietal art was discovered in the Cave of Lubang Jeriji Saleh. It consisted of an animal painting dated to 38,000 BC, during the early Aurignacian in Europe.
The Cave of Lubang Jeriji Saleh contained three particularly ancient items of cave art.
Based on their investigations, the researchers propose a chronological outline with three phases and styles of art, which indicate a shift from painting animals to depicting the human world.
It captures the changing values of Kalimantan hunter-gatherer culture, from a narrow focus on survival to a wider focus on themselves and the environment around them.
For more about the type of pigments used by cave painters in East Kalimantan and elsewhere, see Stone Age Colour Palette.
Because it sheds light on Stone Age culture during the out-of-Africa dispersal of modern humans, thus helping scientists to form a picture of how prehistoric humans began to develop patterns of modern behaviour.
Humans who paint, show that they possess a sense of abstract thinking, because art typically involves the use of symbols.
Also, SE Asia was an important crossroads in the network of migratory pathways taken by African Homo sapiens as they dispersed across the world.
But up until recently, comparatively little paleoart had been recovered from SE Asia and dated.
This led many scientists to believe that the region of Franco-Cantabrian art, in France and Spain, was the centre of Stone Age art.
However, with new discoveries of cave painting in Sulawesi and now Borneo, and perhaps in the Karawari rock shelters of Papua New Guinea, the narrative of the Stone Age is changing.
Futhermore, the islands of SE Asia are full of caves and the area as a whole remains relatively unexplored.
So there could be many other ancient cave paintings and rock engravings, just waiting to be discovered.
And we haven't even mentioned Australia.
Note: To understand how the cave paintings in Borneo fit into the evolution of Stone Age painting as a whole, see our article on the Timeline of Prehistoric Art (from 540,000 BC).
(1)"Cross dating (Th/U-14C) of calcite covering prehistoric paintings in Borneo." Valérie Plagnes, ChristianeCausse, Michel Fontugne, Hélène Valladas, Jean-Michel Chazine, Luc-Henri Fage. Quaternary Research - Volume 60, Issue 2, September 2003, Pages 172-179.
(2) "Palaeolithic cave art in Borneo." Aubert, M., Setiawan, P., Oktaviana, A.A. et al. Nature 564, 254–257 (2018).