Genome-wide evidence of Austronesian–Bantu admixture and cultural reversion in a hunter-gatherer group of Madagascar

Abstract

Linguistic and cultural evidence suggest that Madagascar was the final point of two major dispersals of Austronesian-and Bantuspeaking populations. Today, the Mikea are described as the lastknown Malagasy population reported to be still practicing a hunter-gatherer lifestyle. It is unclear, however, whether the Mikea descend from a remnant population that existed before the arrival of Austronesian and Bantu agriculturalists or whether it is only their lifestyle that separates them from the other contemporary populations of South Madagascar. To address these questions we have performed a genome-wide analysis of >700,000 SNP markers on 21 Mikea, 24 Vezo, and 24 Temoro individuals, together with 50 individuals from Bajo and Lebbo populations from Indonesia. Our analyses of these data in the context of data available from other Southeast Asian and African populations reveal that all three Malagasy populations are derived from the same admixture event involving Austronesian and Bantu sources. In contrast to the fact that most of the vocabulary of the Malagasy speakers is derived from the Barito group of the Austronesian language family, we observe that only one-third of their genetic ancestry is related to the populations of the Java-Kalimantan-Sulawesi area. Because no additional ancestry components distinctive for the Mikea were found, it is likely that they have adopted their hunter-gatherer way of life through cultural reversion, and selection signals suggest a genetic adaptation to their new lifestyle.

Natural selection for the Duffy-null allele in the recently admixed people of Madagascar

“…We obtained similar results from simulations based on the sub-Saharan ancestry proportion (67%) and Duffy-null allele frequency (0.92) that have been estimated for southern coastal populations [9,24]. Only three demographic scenarios produced more than 5% of simulations finishing with Duffynull allele frequencies of at least 0.92, the least extreme of which had an initial N e of 100 individuals, 2% population growth and 33 generations of drift (electronic supplementary material, figure S5).…”

“…¼ 20.2%) than the southern coastal populations (s.d. ¼ 3.23%) [24]. We offer three nonmutually exclusive hypotheses that might explain this observed difference: (i) East Asian/sub-Saharan African admixture may have occurred more recently in the Merina, (ii) the Merina may have mated assortatively with respect to ancestry to a greater extent than the coastal populations, or (iii) some Malagasy from other ethnic groups with different ancestry proportions may have recently adopted the Merina ethnic affiliation, a plausible scenario given that the Merina are the dominant ethnic group and historic rulers of the island.…”

“…A recent analysis of nuclear genomic SNP data from three southern coastal groups estimated the proportion of African ancestry to be 67% [24]. There was also some Near Eastern Islamic cultural influence on the Northwest coast of the island [25], though little evidence of a genetic legacy has yet been described [21,22].…”

Genetic Admixture and Flavor Preferences: Androstenone Sensitivity in Malagasy Populations

“…We tested androstenone perception in four different Malagasy populations who present high genetic and cultural diversity inherited from an ancient admixture between African and Indonesian populations (Razafindrazaka et al 2010, Pierron et al 2014). …”

Forging Ahead By Land and By Sea: Archaeology and Paleoclimate Reconstruction in Madagascar

“…The growing body of archaeological (Boivin et al 2013;Dewar and Wright 1993;Mitchell 2005;Vérin andWright 1999), historical (D'Escamps 1884;De Flacourt 2007;Grandidier 1901;Leitão 1970;Mariano 1904), linguistic (Adelaar 2010;Dahl 1977;Larson 2009;Serva et al 2012), and genetic evidence (Cox et al 2012;Hurles et al 2005;Pierron et al 2014) suggests that waves of migration from all corners of the Indian Ocean-as nearby as the African mainland and as far away as Indonesiacreated Madagascar's complex cultural geography. Each migration brought to Madagascar its own distinctive colonization package (Beaujard 2003(Beaujard , 2011Blench 2007;Fuller et al 2011;Kull et al 2011).…”