Friday 5 July 2024

Re-dating the oldest known figurative cave art.

The rock-art left behind by prehistoric cultures has the potential to provide us with insights into the lives of these long-vanished peoples. Dating this art is notoriously difficult. In the past few decades the predominant approach has been the analysis of uranium and its decay products within flowstone layers partially covering ancient art. Flowstone is formed by the deposition of calcium carbonate onto surfaces by evaporating water; typically water that has flowed through limestone deposits then run out onto a surface such as a cave wall or cliff face before evaporating. The most obvious examples of this are stalagmites and stalactites, though many caves have an interior surfaces covered by flowstone. Where these flowstone deposits occur in caves with paintings they will often overlay the artwork, which means that if the flowstone can be dated, then a minimum age for the art can be established (as the art cannot be younger than the flowstone that overlays it).

This method has been used to date ancient art in many parts of the world, including Western Europe, Island Southeast Asia, and Russia. Notably, a hand-stencil in Spain has been dated to 64 800 years before the present, which implies that it must have been made by a Neanderthal artist, although the reliability of the data used in this study has been questioned. The oldest date we currently have for figurative cave art comes from Sulawesi, Indonesia, where an image of a Warty Pig, Sus celebensis, at Leang Tedongnge in the Maros-Pangkep karst has been given a minimum age of 45 500 years.

The methods used to date flowstone samples to date have relied upon dissolving a sample to form a solution, something which will tend to homogenise the sample, averaging the age of multiple layers overlaying a piece of art, and therefore producing a younger age estimation for the art than if the oldest of these layers could be isolated. 

In a paper published in the journal Nature on 3 July 2024, a team of scientists led by Adhi Agus Oktaviana of the School of Humanities, Languages and Social Science at Griffith University, the Pusat Riset Arkeometri of the Badan Riset dan Inovasi Nasional, the Griffith Centre for Social and Cultural Research, and the Center for Prehistory and Austronesian Studies, and Renaud Joannes-Boyau of the Geoarchaeology and Archaeometry Research Group at Southern Cross University, present the results of a study which used laser-ablation uranium-series dating to provide more accurate dates for the Leang Tedongnge image, as well as other examples of cave art in the same region. 

The laser-ablation method enables the targeting of an area 44 μm in diameter, within a laboratory environment. This enables far smaller samples to be collected than with previous methods, which typically involved grinding a sample from the rockface with a rotary tool. With the laser ablation method it is possible to take a polished thin section of rock, and target points upon that, which is both cheaper and less destructive than traditional methods, as well as far more accurate, as it enables specifically targeting the layer of rock directly overlaying the pigment.

Map of the study area. (a) The Indonesian island of Sulawesi, showing the location of the southwestern peninsula (area inside rectangle). (b) South Sulawesi, with the limestone karst area of Maros-Pangkep indicated by blue shading. The locations of cave sites with dated Late Pleistocene rock art were as follows: 1, Leang Bulu’ Sipong 4; 2, Leang Karampuang; 3, Leang Tedongnge; 4, Leang Timpuseng. Oktaviana & Joannes-Boyau et al. (2024).

At the Leang Bulu’ Sipong 4 site in the Maros-Pangkep karst, a 4.5 m wide panel on the rear wall of a cave depicts a number of Human, or Therianthrope (Human-Animal hybrid) figures, interacting with Warty Pigs and Anoas (Dwarf Buffalo), Bubalus sp.. The figures are holding some form of objects, possibly spears or ropes. The artwork may depict a hunting scene, or possibly a visual representation of a myth.

Dated rock art panel at Leang Bulu’ Sipong 4. (a) Photostitched panorama of the rock art panel. Ther, Therianthrope. (b) Tracing of the dated rock art panel showing the results of laser-ablation uranium-series dating. (c) Transect view of the rock art sample BSP4.5 after removal from the artwork, highlighting the paint layer and the three integration zones (ROIs) and associated age calculations. (d) Laser-ablation-multicollector inductively coupled plasma mass spectrometry imaging of the BSP4.5 thorium²³²/uranium²³⁸ isotopic activity ratio. Oktaviana & Joannes-Boyau et al. (2024).

The imigary at Leang Bulu’ Sipong 4 is covered by four distinct speleothems (flowstone deposits), which have previously been dated to minimum ages of 35 100 years, 43 900 years, 40 900 years, and 41 000 years. The new data obtained by Oktaviana & Joannes-Boyau et al. revises these dates to minimums of 27 600 years, 39 600 years, 39 500 years, and 48 000 years. Most of these ages are similar or older to the previously obtained ages, though one younger date was obtained, possibly because Oktaviana & Joannes-Boyau et al. were careful to avoid areas showing clear signs of post-depositional alteration. 

Since the speleothems overlie the rock art, the oldest speleothem must still be younger than the art, giving a minimum age. The art was previously dated to a minimum of 43 900 years old, but Oktaviana & Joannes-Boyau et al.'s data raises that minimum age to 48 000 years, an increase of over 4000 years, older than the previous oldest dated art at Leang Tedongnge.

At the Leang Karampuang site, again in the Maros-Pangkep karst, a ceiling panel depicts three Human or Therianthrope figures interacting with an Animal, probably another Warty Pig, although the preservation here is poor due to surface exfoliation (flakes breaking off the surface of the limestone), and extensive overlying coralloid growths (small nodes of calcite, aragonite or gypsum that form on surfaces in caves). The image executed in red, and comprises the large, Pig-like Animal, 92 x 38 cm, in side view, with an infill pattern of stripes or lines, consistent with depictions of Pigs and other Animals elsewhere in South Sulawesi. There are other Pig depictions within the Leang Karampuang cave, although it is uncertain if they are the same age as the dated example. The Pig is surrounded by three Humanoid figures. The largest of these is 42 v 27 cm and lacks legs; it has both arms extended and appears to have a rod-shaped object in its left hand.  The second figure measures 28 x 25 cm and is located directly in front of the Pig, with its head in front of the Pig's snout. The final figure, measuring 35 x 5 cm, is upside-down relative to the other figures, with its legs splayed out away from the Pig and one hand reaching towards the Pig's head. A possible fourth figure may have once been present between the first and third figures. There are also at least three hand stencils on the same panel, two which appear to be contemporary with the Pig, plus one darker one which is partially overlain by the Pig, and presumably, therefore, pre-dates it.

Oktaviana & Joannes-Boyau et al. collected samples from four coralloid growths, one overlying each of the figures, plus one from the Pig. The oldest date came from the coralloid overlying the second figure, with a minimum age of 51 200 years. The minimum dates from the first and third figures were 18 700 years and 44 000 years respectively, while the coralloid growth from the Pig yielded a minimum age of 31 900 years. Thus, if the figures and Pig do represent a single piece of artwork, as seems likely, then the whole scene can be assumed to have a minimum age of 51 200 years, making it the oldest known piece of figurative art in the world. 

Dated rock art panel at Leang Karampuang. (a) Photostitched panorama of the rock art panel. (b) Tracing of the rock art panel showing the results of laser-ablation uranium-series dating. (c) Tracing of the painted scene showing the Human-like figures (H1, H2 and H3) interacting with the pig. (d) Transect view of the coralloid speleothem, sample LK1, removed from the rock art panel, showing the paint layer and the three integration zones (ROIs), as well as the associated age calculations. (e) Laser-ablation-multicollector inductively coupled plasma mass spectrometry imaging of the LK1 thorium²³²/uranium²³⁸ isotopic activity ratio. Oktaviana & Joannes-Boyau et al. (2024).

Oktaviana & Joannes-Boyau et al.'s method shows that the Leang Bulu’ Sipong 4 art is over 4000 years older than the previously determined age, with a minimum age of 48 000 years, while the Leang Karampuang art is at least 51 200 years old. These dates significantly increase the maximum known age of figurative art. The oldest known art dates from the Middle Stone Age of southern Africa, between 75 000 and 100 000 years ago, but this comprises geometric marks carved into ochre nodules. Figurative art is presumed to have arisen within Africa, and from there to have been carried around the world by migrating Humans, but there is currently no evidence for this, and it cannot be excluded that this form of expression arose in another region and then spread back to Africa.

The South Sulawesi art also challenges to long-standing preconceptions about cave art, which have come about largely from studies based upon the extensive European rock-art record. These are that Humans and/or Human-like figures did not appear in rock art until the very end of the Pleistocene, and the other is that narrative compositions were absent from early rock art. 

Three of the oldest dated rock art panels in the world come from South Sulawesi, Leang Karampuang, at least 51 200 years old, Leang Bulu’ Sipong, at least 48 000 years old, and Leang Tedongnge, at least 45 500 years old, all include figures, and all appear to involve interactions between the figures and one-another and/or Animals which imply a narrative context. Another piece of cave art, at Leang Timpuseng, dated to at least 35 300 years before the present, depicts a Pig standing in a painted line, presumably representing a ground surface. This depiction of composed scenes presumably had some communicative function, allowing the telling of a story through a narrative interpretation of the art, probably in conjunction with oral storytelling. Thus, this cave-art can also be interpreted as evidence of the emergence of a consistent form of mythology, many thousands of years before any such evidence appears in Europe.

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