Narrative cave art in Indonesia by 51,200 years ago

Prehistoric rock art offers crucial insights into past human cultures but presents significant challenges in accurate and reliable dating. Solution-based uranium-series (U-series) methods have yielded early dates for rock art globally, including Europe, Island Southeast Asia, and Russia. However, these methods, while producing early dates, also present limitations, particularly when dating thin calcite layers with complex growth histories, like the coralloid speleothems often found associated with Indonesian rock art. These complexities include the possibility of mixing carbonate materials of different ages during sampling. The earliest evidence for figurative art before this study was a Sulawesi warty pig painting dated to a minimum of 45.5 ka. This paper aimed to overcome the limitations of previous dating methods by utilizing a novel laser-ablation U-series (LA-U-series) approach. This technique offers enhanced spatial accuracy and precision by analyzing polished cross-sections without the need for chemical preparation. The smaller sample size and high spatial resolution allow for more accurate dating by identifying and avoiding areas affected by diagenesis (alteration of the original material). The researchers hypothesized that the LA-U-series method would reveal older minimum ages for previously dated artwork due to its ability to target specific areas of carbonate growth near the pigment layer, thus avoiding potential age averaging issues encountered with the solution-based method.

The paper reviews existing literature on dating prehistoric rock art, highlighting the use of solution-based U-series methods in various regions, including Spain (where dates for Neanderthal art have been questioned), and Island Southeast Asia (including previous work on Sulawesi's rock art). It acknowledges the limitations of the solution-based approach, particularly concerning the complex morphologies of coralloid speleothems and the potential for mixing carbonate materials of different ages during the sampling process which leads to less accurate dating. The review underscores the significance of accurate dating in understanding the development of human artistic expression and its geographical distribution. The discussion of earlier dating work on Sulawesi's rock art provides a crucial context for the new findings, contrasting the older solution-based U-series results with the more precise and potentially older results from the LA-U-series method.

The researchers employed a novel laser-ablation uranium-series (LA-U-series) dating method to analyze calcite accretions overlying rock art in the Maros-Pangkep karst area of Sulawesi, Indonesia. This method uses a laser to target a specific area on a polished cross-section of the speleothem, allowing for the precise analysis of the oldest carbonate layer closest to the pigment. The high spatial resolution of the LA-U-series method (44 µm spot size) provides several advantages over the previous solution-based method: it is faster and more cost-effective; requires a much smaller and less destructive sample; offers improved spatial resolution to reveal the growth history of the speleothem; and easily identifies and avoids areas exhibiting uranium remobilization, which could affect the accuracy of the dating. The researchers re-dated previously analyzed rock art samples from Leang Bulu' Sipong 4 and conducted new analyses on samples from Leang Karampuang. In contrast to the physical microexcavation and chemical preparation required in the solution-based method, the LA-U-series method employs a laser to map uranium-series isotopes across sample cross-sections, improving the accuracy and precision of age determination. While LA-U-series generally has larger error margins, it can result in older minimum ages by focusing on the carbonate material nearest the pigment, thereby minimizing the influence of later growth stages. The researchers optimized parameters (laser speed and integration time) to balance accuracy and analysis time.

The LA-U-series dating yielded significantly older minimum ages for several rock art panels in Sulawesi. The hunting scene at Leang Bulu' Sipong 4, previously dated to a minimum of 43,900 years ago (ka), was re-dated to a minimum age of 50.2 ± 2.2 ka, representing a difference of 4,040 years. A new rock art scene at Leang Karampuang, depicting human-like figures interacting with a pig, was dated to a minimum age of 53.5 ± 2.3 ka. This scene, painted at least 51,200 years ago, is now considered the oldest known example of representational art and visual storytelling globally. The researchers compared the new LA-U-series dates with previous solution-based U-series dates from the same samples. In most cases, the LA-U-series method provided either similar ages within the margin of error or significantly older minimum ages, highlighting the improved precision and accuracy of the novel method. The exception was one sample from Leang Bulu' Sipong 4 which revealed a younger minimum age, likely due to alteration and diagenesis that could be avoided by the LA-U-series method's selective analysis. The significantly older ages obtained for the rock art at Leang Bulu' Sipong 4 and the newly dated artwork at Leang Karampuang confirm that representational art and narrative scenes existed in Sulawesi much earlier than previously recognized. The analysis of the Leang Karampuang artwork further demonstrates the artistic sophistication of this prehistoric culture, with the depiction of human-like figures interacting dynamically with an animal in a single composed scene.

The findings dramatically revise our understanding of the early history of art, pushing back the timeline for figurative representation and narrative storytelling by at least 51,200 years. The new dates challenge established views that the depiction of anthropomorphs and the creation of narrative compositions were rare in early cave art. The Sulawesi rock art now suggests that figurative art and the ability to tell visual stories developed much earlier than previously believed, potentially arising in Southeast Asia rather than solely in Africa, or later in Europe. The frequency and complexity of the Sulawesi rock art, particularly the recurring theme of human-animal interaction, highlight the rich cultural and artistic traditions of the region's early inhabitants. The improved dating methodology emphasizes the importance of accurate and precise dating techniques in interpreting the archaeological record and understanding the origins of human behavior. The discovery at Leang Karampuang particularly adds significant context by providing clear evidence of narrative representation, adding to the complexity of interpretation of this artistic cultural development.

This study presents compelling evidence that figurative art and narrative storytelling in cave art are far older than previously thought, with the earliest examples in Sulawesi dating back to at least 51,200 years ago. The novel LA-U-series dating method has provided significantly more precise and reliable age estimates for these prehistoric artworks, challenging existing assumptions about the development of human artistic expression and potentially altering our understanding of the origins of art and storytelling. Future research should focus on further application of this refined dating technique to other rock art sites across the globe, seeking to identify additional examples of early figurative art and uncover more details about the development of artistic expression in different parts of the world.

While the LA-U-series method offers significant advantages over previous dating techniques, it is not without limitations. The method does have larger error margins compared to the solution-based U-series methods, although integration of larger areas of data can reduce this error, there is a trade-off in analysis time. Furthermore, the preservation state of the rock art and associated calcite deposits can influence the accuracy of dating. The interpretation of the artwork’s meaning remains open to debate, although the authors provided a plausible interpretation.