It’s a miracle that any prehistoric rock art has survived the millennia, especially when the images aren’t in the depths of a cave but exposed to the elements. Many of these enigmatic images may not survive much longer, though. The increasingly wild weather due to climate change is accelerating the deterioration of some of the oldest images in the world, archaeologists warn.
“The equatorial tropics house some of the earliest rock art yet known, and it is weathering at an alarming rate,” wrote J. Huntley of Griffith University, Australia, with colleagues in Nature last week. More to the point, the deterioration of the images is accelerating with the advance of climate change.
Though this particular paper addresses the specific conditions in 11 archaeological sites in Sulawesi, Indonesia – home of the oldest-known art yet discovered – it bears adding that archaeologists have been sounding the alarm pretty much everywhere, including in Israel’s Negev Desert.
The oldest figurative painting found so far is a picture of a warty pig, which was found in the Leang Tedongnge cave, on the Indonesian island of Sulawesi. It has been dated to at least 45,500 years old. There are hundreds of other caves housing prehistoric art in the area, including the earliest images of therianthropes (human/animal hybrids). These discoveries debunked the assumption that prehistory figurative art had originated in Europe.
Future generations may have to take our word for it, because the art in the 11 sites checked by Huntley and the team are suffering from haloclasty, which is jargon for “salt encrustation.” The change in climatic conditions is catalyzing, encouraging salt deposit on the walls, which is causing blistering and exfoliation, i.e., the limestone surface peels off.
Why? Because these earliest works of art – and they’re so good they can’t have been the first ever – are located in the most atmospherically dynamic region in the world: the Australasian monsoon domain, the authors explain.
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The extreme weather in Australia and horrific results have been making headlines in recent years. In fact, Southeast Asia and Indonesia are not spared. In April, 44 people on the famed Flores Island, where another species of human lived until about 70,000 years ago, were killed in flash flooding.
But for the rock art specifically, the problem is the combination of rising heat, increasingly frequent and prolonged droughts caused by El Niño (which has different effects in different places), interspersed with moister monsoon seasons that create standing water. That may be a boon for rice and fish farmers, but it provides the “ideal conditions for evaporation and haloclasty, accelerating rock art deterioration” on rock shelter and cave surfaces, the team writes.
And thus, the limestone cave surfaces on which pigs, hunters, deer and so much more were painted thousands and tens of thousands of years ago are peeling off – and the pace is evidently accelerating, the researchers say.
We note that the ancient Indonesian art is believed to have been done in two phases: one starting at least 45,000 years ago (but probably earlier), until 20,000 years, in which pigs were a popular motif; and “modern” ones painted, it seems, by Neolithic people who colonized the island of Sulawesi about 4,000 to 2,000 years ago.
Some of the “young” art was painted over “old” art, and in some cases the “young” art was done on cave walls that had largely exfoliated long before – but on which archaeologists can discern some truly ancient artwork. Such as the incredible earliest depiction of a hunt narrative 44,000 years ago.
It also bears saying that some prehistoric art was done deep inside – sometimes very deep inside – caves. (Recently, Israeli archaeologists posited that such deep-cave art was likely done in a state of hypoxic ecstasy.) It may not be exposed to rain, but such art is also vulnerable to changing conditions.
Because climate change is not being mitigated, since emissions continue apace with nary a sign of easing, since temperatures keep climbing, and since the El Niño events are expected to grow ever more severe, the researchers warn that the trend is set to accelerate.
Another major threat to these enigmatic whispers from the dimmest reaches of human history is limestone quarrying. And then there are other threats to prehistoric petroglyphs and art wherever they may be – such as pollution and bacteria.
Archaeology has often put perspective on past climate and environmental change: “Such studies shed light on how we arrived at the present day and help us search for sustainable trajectories toward the future,” Torben Rick and Daniel Sandweiss wrote in 2020.
Archaeology, with the help of anthropology, has helped prove that humankind has been changing the planet not since the start of the industrial age, not just since the advent of settlement (and deforestation for that purpose), but for at least 100,000 years. Much of the interpretation of prehistoric art remains controversial, but one thing that’s not arguable is that some prehistoric panels show now-extinct animals, such as giant sloths and mammoths. These pictures have much to teach us, but now they’re deteriorating at an ever-faster rate.
So are the pyramids in ancient Egypt, by the way, thanks to the mounting heat and weather extremes; ditto the Western Wall, which this February underwent its periodic face-lift to halt deterioration from pollution and acidic rain – it’s also peeling.
And never mind coastal archaeological sites in danger of being flooded. At least the case of the flooded putative village that may or not be Bethsaida, by the Sea of Galilee, is reversible: the lake rose and inundated the site after heavy winter rains, and the water level will presumably fall back again. But sites where the sea is rising can expect no succor.
Can anything be done to preserve these precious artifacts of yore, at least the rock art? A collaboration between Israeli and Austrian scientists is studying the bacteria currently afflicting prehistoric petroglyphs in the Negev and the Alps, to understand their contribution to the rocks’ decay. But even they admit that their work isn’t likely to save the thousands of petroglyphs in the Israeli desert, or the Alps. At best, any understandings they gain may serve to preserve a select number, or more recent monuments.
And it certainly won’t do a thing for paintings disappearing, after all these thousands of years, because of climate change.