Coevolution of languages and genes on the island of Sumba, eastern Indonesia

Abstract

Numerous studies indicate strong associations between languages and genes among human populations at the global scale, but all broader scale genetic and linguistic patterns must arise from processes originating at the community level. We examine linguistic and genetic variation in a contact zone on the eastern Indonesian island of Sumba, where Neolithic Austronesian farming communities settled and began interacting with aboriginal foraging societies Ϸ3,500 years ago. Phylogenetic reconstruction based on a 200-word Swadesh list sampled from 29 localities supports the hypothesis that Sumbanese languages derive from a single ancestral Austronesian language. However, the proportion of cognates (words with a common origin) traceable to Proto-Austronesian (PAn) varies among language subgroups distributed across the island. Interestingly, a positive correlation was found between the percentage of Y chromosome lineages that derive from Austronesian (as opposed to aboriginal) ancestors and the retention of PAn cognates. We also find a striking correlation between the percentage of PAn cognates and geographic distance from the site where many Sumbanese believe their ancestors arrived on the island. These language-gene-geography correlations, unprecedented at such a fine scale, imply that historical patterns of social interaction between expanding farmers and resident hunter-gatherers largely explain community-level language evolution on Sumba. We propose a model to explain linguistic and demographic coevolution at fine spatial and temporal scales.Austronesian languages ͉ cognate ͉ contact zone ͉ language evolution ͉ Y chromosome haplogroups L anguages, like populations, change over time, but the rules governing language change are still not well understood. Because lexical and structural innovation, borrowing, and loss are difficult to observe and quantify over brief periods (1) and are impossible to witness over long periods, researchers are forced to undertake indirect approaches to infer the processes of language change. One such approach is to look for associations between linguistic and genetic classifications. Many well-known studies have identified associations between the languages and genes of human populations at continental and global geographic scales (2-6).

Bringing together linguistic and genetic evidence to test the Bantu expansion

“…Such associations among genetic, linguistic and geographical distances were also found at a finer geographical scale among Austronesianspeaking populations in the eastern Indonesian island of Sumba [30] and in Northern Island Melanesia [31]. Our results thus confirm the general view of anthropological genetics that the Bantu expansion took place via a demic diffusion [1,15,18 -20], although they contrast with the results of Sikora et al [21].…”

Autosomal and X-linked single nucleotide polymorphisms reveal a steep Asian–Melanesian ancestry cline in eastern Indonesia and a sex bias in admixture rates

“…Alternatively, as pointed out in many previous studies based on both genetic (Cox 2005(Cox , 2006(Cox , 2008Karafet et al 2005;Hill et al 2007;Lansing et al 2007;Mona et al 2009) and archaeological data (Bellwood 2005(Bellwood , 2007, there is good evidence that significant Asian contact occurred in eastern Indonesia and Melanesia during the Austronesian expansion. Indeed, much of the pattern of admixture we observe in this study, especially in Wallacea and Near Oceania, may well reflect cultural processes associated with the expansion of Austronesian farmers into the territory previously occupied by Melanesian hunter-gatherers (given subsequently).…”

“…In particular, to the west of Sumba and Flores, Asian ancestry approaches 100 per cent; while east of Alor, evidence of Asian ancestry diminishes dramatically (see below). Alor is among the most westerly locations where Papuan languages are spoken, and Melanesian Y chromosome lineages are common on all of these islands (Lansing et al 2007(Lansing et al , 2008, but not further west (Karafet et al 2005). …”

“…Sample sizes varied, but averaged to 33 genotypes per SNP per population (electronic supplementary material, table S2). Sample details are available elsewhere (Karafet et al 2005;Lansing et al 2007Lansing et al , 2008, with the exception of New Britain, which is a composite sample of individuals from two inland, Papuan-speaking regions in eastern New…”

Climate Change Influenced Female Population Sizes Through Time Across the Indonesian Archipelago

“…First, individual households may actually contain multiple generations of reproductive age women. Second, BSPs assume that sampled communities form natural populations, but Indonesian communities are typically structured with evidence of frequent interpopulation migration (Lansing et al 2007).…”