Contact or Inheritance? New Evidence on the Proto-Philippines Hypothesis

Abstract: A central issue in Austronesian higher-order subgrouping concerns the position of the Philippine languages. Despite considerable debate, it remains unsettled whether these languages represent multiple intersecting Malayo-Polynesian primary branches forming a linkage, or whether they descend from a single shared ancestor distinct from Proto-Malayo-Polynesian. We present three new lines of evidence supporting the former view. First, the absence of a genuine *d/*z merger in Central Luzon and Minahasan languages undermines the sole phonological argument for a Proto-Philippine branch. Second, the geographical distribution of the purported Proto-Philippine-defining lexicon favors a diffusion-based explanation. Third, the distribution of an under-explored morphological innovation across Philippine languages suggests frequent contact among major island groups, excluding interior and peripheral areas. These findings not only highlight the absence of defining innovations for a cohesive Proto-Philippine but also point to extensive horizontal transmission across the archipelago, extending beyond lexical exchange. We further propose that the *d/*z merger is better understood as an areal drift rather than a diagnostic innovation. We conclude that Philippine languages are best analyzed as intersecting Malayo-Polynesian primary branches, in line with recent perspectives. Moreover, the high number of proposed lexical innovations attributed to Proto-Philippine likely reflects contact-driven processes—diffusion, borrowing, and linkage histories—rather than retention from a unified ancestor.