A 4000 Year-Old Introduction of Domestic Pigs into the Philippine Archipelago: Implications for Understanding Routes of Human Migration through Island Southeast Asia and Wallacea

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Introduction

Bellwood (1997, 2006) proposed that migrating farming communities from mainland China entered the Philippines via Taiwan between 4000 and 4500 years ago (Ka), bringing with them ground-stone technologies and pottery. Archaeological, bacterial and linguistic evidence suggest that these Austronesian-speaking peoples travelled onwards from the Philippines through Borneo in the west and Sulawesi to the south, eventually occupying the whole of Island Southeast Asia (ISEA), Melanesia and Oceania (Gray et al. 2009; Moodley et al. 2009). This hypothesis has been challenged by a number of archaeologists and geneticists who have argued that connections with mainland Southeast Asia, as opposed to Taiwan, are responsible for the Austronesian languages and agriculture in ISEA (Oppenheimer 1999; Solheim 2006). Solheim (2006), in particular, has argued for a strong similarity in Neolithic material culture between Vietnam and ISEA. Three domestic animals, the pig, dog and chicken, along with rats (commensals), all originated on the Asian mainland and are traditionally associated with the early farming communities of ISEA. They are commonly used as a proxy for identifying origins and routes of human migration in the past (Larson et al. 2005, 2007a, b & c; Liu et al. 2006; Matisoo-Smith 2007; Dobney et al. 2008). Reconstruction of human migration routes through ISEA using domestic pigs is based primarily on genetics, and relies almost exclusively on interpretation from modern population distributions. Based on these results, the earliest and most widespread domestic pigs introduced to ISEA are known as the 'Pacific Clade', and are believed to be the only lineage to have reached the Pacific islands in the company of colonising human populations. They appear to have originated somewhere in peninsular Southeast Asia and were transported through Malaysia, Sumatra, Java and islands in Wallacea (Flores, Timor, Moluccas) (Larson et al. 2005, 2007a & b; Dobney et al. 2008), thus adding some support to Solheim's claims for a Vietnam/ISEA connection.

There are difficulties in differentiating domesticated Sus scrofa from the wild progenitor and other close relatives such as the S. verrucosis/scrofa groups in the ISEA archaeological record. The only securely dated domesticated suid bones come from islands outside the natural range of these taxa, such as Flores, where they were possibly introduced between 3500 and 4000 years ago (Dobney et al. 2008; van den Bergh et al. in press), in the northern Moluccas at 3500 cal BP (Kayoa Island: Bellwood & White 2005), and in Lapita sites in Melanesia from around 3300 cal BP (Summerhayes 2007). A second lineage of modern domestic pigs identified in the Philippines appear to have a very different origin in East Asia (China), and were transported via Taiwan into the Philippine Archipelago, and then on to Micronesia (Larson et al. 2007a & b; Dobney et al. 2008). In the absence of any archaeological evidence to indicate the timing of domestic pig introduction to the Philippines, Dobney et al. (2008) suggested that this human-mediated dispersal was probably later than the translocation of the 'Pacific Clade' of pigs from the mainland to Australasia and the Pacific.

Recent excavations at the site of Nagsabaran on the northern Philippine island of Luzon have produced a small but significant bone assemblage dating to the Neolithic and Metal Age. The human-derived bone accumulations contained the native brown deer Cervus mariannus along with fish, mostly Sparidae, turtle and two different species of pig (Piper et al. 2009). One species was identified as a domesticate Sus scrofalverrucosus and directly radiocarbon dated using a single fourth premolar to 4500-4200 cal BP. This new evidence from Nagsabaran suggests that domestic pigs were possibly introduced from Taiwan to the northern Philippines prior to the translocation of the 'Pacific Clade' from the mainland through ISEA, Wallacea and on to Australasia and the Pacific. …