Which Sounds Change: Descent and Borrowing in the Skou Family1

The process of establishing genetic relationships in the endeavor of historical linguistics is complicated by the fact that some, if not most, languages show no inclination to “behave themselves” by re3ecting only material inherited from their protolanguage. Borrowing at many levels is rife in many languages, particularly when geographic separation is slight, and when social contact is frequent. When both language-internal change and language-external change happen during the same time frame, sorting out relations can be complicated. In this article I show that not all sounds behave equally with respect to areal spread. This is presented through a study of sound changes in the Skou languages of New Guinea, and a survey of other reports of diffusing behavior from elsewhere. Recognizing and working with these differences can allow us to sort out relative chronologies and thus historical relations in even complex scenarios of borrowing and change.