People struggle to name odors [1-4]. This has been attributed to a diminution of olfaction in trade-off to vision [5-10]. This presumption has been challenged recently by data from the hunter-gatherer Jahai who, unlike English speakers, find odors as easy to name as colors [4]. Is the superior olfactory performance among the Jahai because of their ecology (tropical rainforest), their language family (Aslian), or because of their subsistence (they are hunter-gatherers)? We provide novel evidence from the hunter-gatherer Semaq Beri and the non-hunter-gatherer (swidden-horticulturalist) Semelai that subsistence is the critical factor. Semaq Beri and Semelai speakers-who speak closely related languages and live in the tropical rainforest of the Malay Peninsula-took part in a controlled odor- and color-naming experiment. The swidden-horticulturalist Semelai found odors much more difficult to name than colors, replicating the typical Western finding. But for the hunter-gatherer Semaq Beri odor naming was as easy as color naming, suggesting that hunter-gatherer olfactory cognition is special.
The Aslian language family, located in the Malay Peninsula and southern Thai Isthmus, consists of four distinct branches comprising some 18 languages. These languages predate the now dominant Malay and Thai. The speakers of Aslian languages exhibit some of the highest degree of phylogenetic and societal diversity present in Mainland Southeast Asia today, among them a foraging tradition particularly associated with locally ancient, Pleistocene genetic lineages. Little advance has been made in our understanding of the linguistic prehistory of this region or how such complexity arose. In this article we present a Bayesian phylogeographic analysis of a large sample of Aslian languages. An explicit geographic model of diffusion is combined with a cognate birth-word death model of lexical evolution to infer the location of the major events of Aslian cladogenesis. The resultant phylogenetic trees are calibrated against dates in the historical and archaeological record to infer a detailed picture of Aslian language history, addressing a number of outstanding questions, including (1) whether the root ancestor of Aslian was spoken in the Malay Peninsula, or whether the family had already divided before entry, and (2) the dynamics of the movement of Aslian languages across the peninsula, with a particular focus on its spread to the indigenous foragers.