Mainland-coastal interactions in East Borneo: Inter-site comparison and Bayesian chronological models of two Late Pleistocene–Holocene sequences (Liang Abu and Kimanis rock shelters)

Abstract

In recent decades, East Borneo has become an increasingly important archaeological “hot-spot” in Island Southeast Asia as a result of early dates for rock art ca. 38,000 BP and the greater number of excavated sites that support a much longer period of human occupation. However, the chronology of settlement and adaptation to environmental changes during the Pleistocene–Holocene transition is still poorly known. Here we report on an excavation at the Liang Abu rock shelter which has contexts dating from the Late Pleistocene (12,660 ± 58 uncal. BP) to the present day, indicating a terminus ante quem (TAQ) for human occupation at 23,790 BP. We present the results of an attempt to systematically integrate and compare data from Liang Abu and Kimanis, a geographically close site with a previously published sequence. Particular attention is paid to post-depositional issues in tropical settings and to data compatibility, reuse, and reproducibility, relying on open-source software for data processing (R scripts) and Bayesian chronological modeling. Two Bayesian models are built and compared using the ChronoModel software, which can handle outliers and uncertainty (e.g., freshwater reservoir effect). This first inter-site comparison for Borneo results in a new chronology of human settlement and mainland–coastal interactions in East Borneo and paves the way for future regional synthesis.

Keywords:

• Island Southeast Asia
• excavation
• coastal adaptation
• post-depositional processes
• Austronesian studies

Correction Statement

This article has been republished with minor changes. These changes do not impact the academic content of the article.

Supplementary Data

1. Excavation and layers description

2. Data and R Packages

3. Figure 6: Spatial density of lithic, pottery, and shell remains, layer

4. Figure 7: Orientation and number of relationships

5. Pottery refitting: cohesion and admixture of layers

6. Figure 8: Density by class of remains

7. Figure 9: Density of stone artefacts and shells

8. Figure 10: Fauna by class

9. Figure 11: Fauna, shells

10. Figure 12: Stone artefacts

11. Stone artefacts: chi-test on classes in Liang Abu and Kimanis

12. Stone artefacts: chi-test on raw material classes in Liang Abu and Kimanis

13. Stone artefacts: lengths of flakes from Liang Abu and Kimanis

14. Figure 14: Results of the “conservative” chronological Bayesian model

15. Supplementary Figure 16: View of the shelter

16. Supplementary Figure 17: Insect holes in the north section

17. Supplementary Figure 18: Insect pupa

18. Supplementary Figure 19: Roots in sub-square 11Ed

19. Supplementary Figure 20: Comparison of the density of micro-remains

20. Supplementary Figure 21: Comparison of the density of micro-remains (2 mesh sizes)

21. Supplementary Figure 22: Fauna by order

22. Supplementary Figure 23: Fauna by family

23. Supplementary Figure 24: View of layer 2 during excavation, sub-square 12Ec

24. Supplementary Figure 25: Diagram of the “restricted” Bayesian model

25. Supplementary Figure 26: Results of the “restricted” Bayesian model

Acknowledgements

We thank former participants in the MAFBO project (https://kaltim.hypotheses.org): Jean-Georges Ferrié, Bénédicte Voeltzel, Michel Grenet, and Josette Sarel; Jean-Bernard Huchet for insect classification, Tim Thomas for his suggestions, and Philippe Lanos and Philippe Dufresne for their support on chronological modeling. We also acknowledge support from the LabEx TULIP, France and thank the Kabupaten Kutai Timur authorities, the Direktorat Pelestarian Cagar Budaya dan Permuseuman (BPCB, Samarinda), the Pusat Penelitian dan Pengembangan Arkeologi Nasional (National Research Center for Archaeology, Jakarta), the Kemenristekdikti for the Foreign Research Permit, the Balai Arkeologi Banjarmasin (Banjar Baru, Kalimantan Selatan), and the Merabu people for their help and support. Finally, we thank the reviewers and editors of The Journal of Island and Coastal Archaeology for their comments and support.

Authors’ contributions

Sébastien Plutniak: Conceptualization, Methodology, Formal analysis, Investigation, Writing—Original Draft, Writing—Review & Editing, Visualization. François-Xavier Ricaut: Investigation, Writing—Review & Editing, Supervision, Project administration, Funding acquisition. Astolfo Araujo: Investigation, Writing—Review & Editing. Jean-Michel Chazine: Writing—Review & Editing. Bambang Sugiyanto: Investigation. Adhi Agus Oktaviana: Investigation, Project administration.

Disclosure statement

No potential conflict of interest was reported by the authors.

Data and material

• The Liang Abu’s pottery data: 10.5281/zenodo.3929562

• Liang Abu lithic data: 10.5281/zenodo.6774519.

• Liang Abu fauna data: 10.5281/zenodo.6774530

• The Bayesian models and the results are available at: https://doi.org/10.5281/zenodo.3929615.

• The sea level dataset from Sathiamurthy and Voris (2006) is available at: https://doi.org/10.5281/zenodo.3929568

Ethical declaration

All samples used for dating (remains, charcoal, shell) were obtained after discussions with stakeholders and people of the Merabu community village. The study was approved by the Pusat Penelitian Arkeologi Nasional (ARKENAS), Jakarta, Indonesia (n^r 1420/P4/Kemendikbud/2013). Permission to conduct research in Indonesia was granted by the State Ministry of Research and Technology (RISTEK) to F.-X. Ricaut (Permit number: 2C13JD0571-L).

Notes

1 MAFBO: Mission Archéologique Française à Bornéo, https://kaltim.hypotheses.org.

2 The Maau formation is about 1800 m thick. Its lower part consists of interbedded breccia, conglomerate, sandstone, limestone, marl, shale, and tuff. The upper part consists of interbedded clay-stone, siltstone, sandstone, and calcite veinlets (Sukardi et al. 1995).

3 See Chazine et al. 2009, 2010; Ricaut et al. 2011, 2012, 2013, 2014.

4 In 2009, the sediments were dry sieved through a 5 mm sieve.

5 For a detailed description of the excavation procedure and layers, see Supplemental 1, Section 1.

6 Two-Dimensional Kernel Density Estimation (Venables and Ripley 2002) implemented in the MASS 7.3-45 package for R. As demonstrated by our tests, the random spatial assignation of the objects has no effect on the general features of their distribution pattern.

7 See Supplemental 1, Section 5.2.

8 We thank Jean-Bernard Huchet for his attempt to identify these insects.

9 χ² = 44.824, p-value = 1e-05.

10 For 5 mm mesh size: χ² = 28.628, p-value = 2e-05; for 2 mm mesh size: χ² = 19.512, p-value = 0.00036.

11 These identifications must be considered cautiously, since they were not made by a qualified malacologist, but by using the standard taxonomic categories used in the regional archaeological literature.

12 Wilcoxon test, W = 9050, p-value = 0.4518, see Supplemental 1, Section 13.

13 See supplementary data for the numerical results.

Additional information

Funding

This research was supported by French ANR grant number ANR-14-CE31-0013-01 (grant OceoAdapto to F.-X. R.), the French Ministry of Foreign and European Affairs (Mission archéologique française à Bornéo to F.-X. R.), and the French Embassy in Indonesia through its Cultural and Cooperation Services (Institut Français en Indonésie).