Mortars and Pestles Make the Mid-Holocene Occupation of New Guinea and the Bismarck Archipelago Visible
Stone mortars and pestles are distributed across New Guinea, but few have been found in West Papua. As they are now securely dated to the Mid-Holocene, their distribution can be used as the basis for modelling Mid-Holocene population concentrations. Artefacts with elaborate morphologies also allow the modelling of social interaction. The declining availability of the Castanopsis nut following land clearance would have played a major role in the abandonment of mortars and pestles in the highlands. Decreasing coastal connectivity due to the infilling of the Sepik-Ramu inland sea may have also played a role in this abandonment. The continued availability of canarium and coconuts in coastal areas allowed the making of nut and starch puddings to continue. However, the pottery bought by Austronesian speakers (Lapita) would have allowed tubers to be steam-cooked, and the softer result probably led to stone versions of mortars and pestles being abandoned and replaced with wooden versions.