Island Southeast Asia has been the subject of important archaeological discoveries regarding human evolution and recent human population history. Within this context, East Borneo is of special interest because of its strategic location on the edge of Sundaland facing the Wallace line. Relatively little is known about the prehistory of Eastern Borneo, mainly due to exploration difficulties in this karstic region.
Since 2003, an archaeological research project coordinated by Puslitbang Arkeologi Nasional (Indonesia) and CNRS (University of Provence and University of Toulouse, France) has been developed on the karstic region of East Kalimantan (Mangkalihat peninsula, Indonesia). Since 2010, a new multidisciplinary project was initiated involving archaeological, anthropobiological and ethno-linguistic approaches, essential for uncovering the human occupation process during human history.
Previous surveys have led to the unexpected discovery of more than 150 caves with unique rock art paintings (mostly hand stencils), dating back to at least the early Holocene (9900 years BP) and presenting some similarities to those from Eastern Indonesian Islands, West Papua and Australia. These discoveries attested for the first time of an early human occupation in Eastern Borneo.
Additional surveys in 2010-2012 have selected caves or shelters presenting a strong excavation potential to answer our research problematic.
The Liang Abu rock shelter
Liang Abu is located 130km north-west from the shore of Makassar Strait within the rainforest of a mountainous karstic area. Hundreds of cliff caves and shelters are present, where human activities occurred on three levels: human settlements at the base, burials in the middle and rock art at the top.
The Liang Abu site is a vast and dry rock shelter facing east. Its dimensions are around 25m in maximum length and a width of between 5 and 8m. The site is located 6km from the remote Lebbo’ village of Merabu. The Lebbo’ are the only ethnic group which have lived in this inner region for a long time. Ethno-linguistic studies of their oral traditions and cultural practices are on-going to underpin the former uses of the caves in relation to the proto-historic and pre-historical periods in the region. Some of their representations can be related to the prehistoric rock art found in nearby caves.
All these characteristics have made Liang Abu a good site to investigate the link between late Pleistocene human occupation, rock art and their contemporary populations and their potential descendants.
To test the archaeological potential of the site, four test-pits were carried out in 2009. They have been opened up to a depth of 1m, but the bedrock has not yet been reached. Seven levels have been identified; all of them have provided archaeological material.
Among the 480 earthenware sherds that have been recorded, 113 present specific typological features — rims, rim/body juncture or carination — and 59% are decorated. The majority of sherds were found in an undisturbed layer 20 cm from the surface. Radiocarbon dating of this layer will supply useful information regarding the spread of earthenware technology in this region.
Perhaps the most striking results are from the techno-typological analysis of the lithic assemblages. The tools types consist mainly of a wide range of retouched flakes and small points on flake, which has never been described before through all the stratigraphy. Based on a morphological study, it may be assumed that these points were used on smooth materials like rattan, wood or bones. Microwear analysis will precise their functions.
Almost 10 000 animal bone fragments were recovered, the majority (~70%) were indeterminate. The faunal remains were highly fragmented and 40% of the assemblages were burnt. Mammals and reptiles were the main taxonomic groups, whereas birds and fishes remains were rare. Among the mammals, the bearded pig (Sus barbatus) was the principal hunted prey.
The presence of a bone industry was also documented by 18 modified small bone fragments. A detailed analysis will identify the manufacture processes and their potential function.
The surveys conducted at Liang Abu in 2009 have documented the presence of important past human occupations in this rock shelter and confirmed the lasting presence of a peculiar lithic industry. Excavations in 2012-2014 will precise the nature and chrono-stratigraphy of these occupations, and a pluridisciplinary approach will provide an exceptional opportunity to bring new archaeological data on a poorly studied key area for human evolution and history in Southeast Asia.
Citation: Ricaut F.-X., Grenet M., Plutniak S. and the MAFBO team. “Liang Abu rock shelter presentation”. Published online 12 june 2015. http://kaltim.hypotheses.org/793