Possible Origins of Infixation in Khmer

The existence of infixation in Austroasiatic has always been treated as a given: one of such antiquity that it has been proposed as a possible index of genetic affiliation with Austronesian. Nor does the comparative method allow the reconstruction of a typologically more plausible set of prefixes from which the attested infixes could have been derived via metathesis. Yet a plausible mechanism for the infixation process can be suggested on the basis of internal reconstruction, given the following facts about Khmer: 1. A canonical iambic word structure; 2. An ongoing process of initial syllable erosion whose most consistent effect is the simplification and reduction of the rhyme of the anacrusic syllable. Both facts, although currently attested, are also of great antiquity in Austroasiatic. In Viet-Muong, the process of erosion, unchecked, led to a lexicon of monosyllabic roots. In (Mon-)Khmer, erosion created a perceived gap in the structure of the word. Infixation plugs that gap.