The Archaeological Investigation of Rock Art in the Philippines

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Austronesians are a genetically-related people, recognized by the similarities in their languages, and with a shared past evidenced by material culture. Research into the origin and migration route of Austronesians has progressed through the disciplines of Linguistics, Archaeology, and Genetics. Out of Taiwan is currently the dominant theory with strong evidence from the three disciplines involved. Consequentially, the Philippines is the first stop of the migrating Austronesians, and therefore the closest link to the homeland in Taiwan linguistically, archaeologically, and genetically. The archaeological approach to understand the Austronesian diaspora has been tracing material culture like nephrite and ceramics. However, rock art as a traceable material culture has been underutilized, especially in places like the Philippines where the rock art is relatively unknown and lacks research. The two rock art styles that have been identified in Borneo, East Timor, and Southwest Pacific and have been linked to Austronesians are the Austronesian Painting Tradition (APT) and the Austronesian Engraving Style (AES). The aim of this research has been to test the validity of APT and AES in the Philippines. An inventory of rock art of the Philippines was needed to enable descriptions and comparisons with the region. This was achieved through low-cost 3D modelling using Structure-from- Motion (SfM) photogrammetry. However, the physical and socio-economic environment in the Philippines makes rock art research a difficult undertaking. One of the challenges of studying Philippine rock art was the geological condition obfuscating the rock art at some of the sites. Remote sensing techniques were used during this research to address the issue. Specifically, an innovative method of combining SfM and GIS (Geographic Information Systems) algorithms was developed so that obscure engraved rock art was made clearly visible. Being able to properly identify the rock art allowed for a more accurate inventory, thereby increasing the reliability of the interpretations. There are 22 verified rock art sites in the Philippines and seven areas with alleged sites. Of the verified sites, four have engravings, 16 have black figures, and two have predominantly orange figures. Four of the sites (three engraving and one painting site) were completely recorded with 3D models which resulted in spatially-linked databases of the three engraving sites. All other sites were described from past publications, museum reports, and empirical observations. By compiling the rock art in an inventory and comparing the inventory to the prescribed qualities of APT and AES, it is evident that APT and AES are not descriptive of Philippine rock art. Furthermore, primary sources of Taiwanese rock art reveal that it is highly unlikely APT originated in Taiwan since there is no known painted rock art on the island. Although the Taiwanese engraved rock art matches the description of AES and could therefore originate in Taiwan, it is inconclusive because the description of AES is too generic. A systematic quantitative literature review of the rock art of Southeast Asia and Micronesia was compiled to ascertain the amount of research conducted and to compare the inventory of the Philippines with the rock art of the region. For example, parallels in anthropomorphic depictions are found within the Philippines and between the Philippines and the region. Aside from determining similarities, conspicuous absences in motifs and styles were also noted, such as hand stencils and painted boats. An example of the unique aspect of Philippine rock art is the textured vulva-forms of Alab because they are not similar to the few other examples of engraved vulva-forms in Southeast Asia. In addition, a summary of Micronesian rock art is provided which might be the first for the region. Micronesian rock art potentially has information of an Austronesian style of rock art. The first colonizers of Micronesia were Austronesians and they remained the sole inhabitants for millennia on some islands until European contact in the 16th century, making the rock art found in Micronesia very likely Austronesian. Cost-effective techniques were emphasized throughout the research, not just as an efficient way to conduct this particular research but also to encourage the continuity of the research into Philippine rock art. Beyond the Philippines, the methods are relevant to any rock art research on a limited budget, which is typical of most rock art projects. It should be noted that the methods employed, while low-cost, were still state-of-the-art for rock art recording. With a baseline of the current conditions of the rock art sites, a longitudinal study can be organised for the quantitative monitoring of change. In addition to answering archaeological questions, the inventory can be used to develop conservation plans and influence government policies.