In 1921, the population of Bougainville was recorded at 46,832. The Australian district officer was based at Kieta and controlled a native police force of 40 constables and five officers. The civil administration "pursued pacification less ferociously than its military predecessor" and recruited Bougainvilleans as interpreters. The administration established larger "line villages" in place of the smaller hamlets, in order to simplify collection and "condition the able-bodied men to the barracks discipline on the plantations". German ethnographer Richard Thurnwald returned to Buin in 1933 following an earlier visit in 1908. He noted a number of changes over the 25-year period, including a large increase in literacy, the introduction of a cash economy (comprising both coins and shell money), the erosion of chiefly authority, a decrease in headhunting, and the introduction of feast-giving as a surrogate for war.