A recent squib by Mark Donohue in Oceanic Linguistics on the naturalness of the sound change t > k. Includes data from Australian languages.
Robert Blust raises the issue of the *t > k change that is widely attested in Austronesian languages, but infrequently in other language families. He offers both structural and perceptual explanations for the “naturalness” of this change, but admits that the data raise more questions than can be answered. I offer support for the view that this change is not unnatural, based on the distribution of stop types cross-linguistically, and the patterns that are found. I introduce another kind of argumentation, that of typologically determined systemic naturalness, in the spirit of Evolutionary Phonology