The partitioning of people by language is perhaps more extreme on the Sepik coast than anywhere else on earth. Shortly before World War I, the Field Museum of Natural History in Chicago acquired ethnographic material culture collections from a number of village communities there. Computer-aided social network analysis of these collections suggests that isolation by distance, rather than by language, has patterned their cultural relationships. Furthermore, it would be difficult for archaeologists to successfully “reverse engineer” existing language boundaries along this coastline given only observed differences in historic material culture.