“…By exploring endemic Pandanus nuts and yams right after settlement (Summerhayes et al, ) and experiencing minimal impact of malaria (Riley, ), Highland populations gradually reached high densities surpassing those of the lowlands, and previously isolated populations would increasingly come into contact with each other (Bulmer & Bulmer, ). Although patrilocal exchange of brides among territorially adjacent clans have been reported to occur often in the Highlands (Feil, , ; Gajdusek & Alpers, ), long‐distance travel was still discouraged by the mountainous landscapes, cultural differences (e.g., language) and constant, low intensity warfare with surrounding groups (Podolefsky, ). As part of the culture, languages would also diverge and evolve through a similar process like genes in Highlands, accompanying colonization, isolation, and subsequent migration of people (Levinson & Gray, ; Nettle, ).…”