African origin for Madagascan dogs revealed by mtDNA analysis

Abstract

Madagascar was one of the last major land masses to be inhabited by humans. It was initially colonized by Austronesian speaking Indonesians 1500-2000 years ago, but subsequent migration from Africa has resulted in approximately equal genetic contributions from Indonesia and Africa, and the material culture has mainly African influences. The dog, along with the pig and the chicken, was part of the Austronesian Neolithic culture, and was furthermore the only domestic animal to accompany humans to every continent in ancient times. To illuminate Madagascan cultural origins and track the initial worldwide dispersal of dogs, we here investigated the ancestry of Madagascan dogs. We analysed mtDNA control region sequences in dogs from Madagascar (n=145) and compared it with that from potential ancestral populations in Island Southeast Asia (n=219) and sub-Saharan Africa (n=493). We found that 90% of the Madagascan dogs carried a haplotype that was also present in sub-Saharan Africa and that the remaining lineages could all be attributed to a likely origin in Africa. By contrast, only 26% of Madagascan dogs shared haplotypes with Indonesian dogs, and one haplotype typical for Austronesian dogs, carried by more than 40% of Indonesian and Polynesian dogs, was absent among the Madagascan dogs. Thus, in contrast to the human population, Madagascan dogs seem to trace their origin entirely from Africa. These results suggest that dogs were not brought to Madagascar by the initial Austronesian speaking colonizers on their transoceanic voyage, but were introduced at a later stage, together with human migration and cultural influence from Africa.

Keywords: Austronesian expansion; Canis familiaris; Indian Ocean exchange; Madagascar; cultural diffusion; mtDNA.

Figure 1.

Map showing major sampling regions in Madagascar, Africa and Indonesia. Light green circles represent sampling regions. The number of samples is given for the major sampling regions; minor regions with 6–33 samples are represented by small circles. The sample from Southeast Borneo, the region suggested as the origin for the Austronesian language spoken on Madagascar, is indicated by a red circle. The regions designated as West, upper East and lower East sub-Saharan Africa are separated by green lines.

Figure 2.

Minimum-spanning networks showing relationships between the haplotypes in the major mtDNA haplogroups A, B and C, and representation of the haplotypes in Madagascar, Indonesia, and East and West sub-Saharan Africa. Circles represent mtDNA haplotypes, lines connecting haplotypes represent a single substitution step, and black dots represent hypothetical haplotypes. The 17 universal haplotypes (UTs) are indicated with black bold outlining. Circles with red bold outlining represent haplotypes corresponding to the ‘Austronesian signature’ 263 bp haplotype Arc2. For Madagascar, pink circles represent haplotypes unique to Madagascar compared with the other three regions, purple represents haplotypes shared with both sub-Saharan Africa and Indonesia, and green represents haplotypes shared only with sub-Saharan Africa. Importantly, no haplotypes were shared exclusively between Indonesia and Madagascar. For Indonesia and East/West sub-Saharan Africa, yellow circles indicate haplotypes shared with Madagascar, and blue circles haplotypes not shared with Madagascar. For clarity of the picture, nine haplotypes are not shown (see the electronic supplementary material, figure S1).

Figure 3.

Indigenous dogs from Ranomafana (left) and Antananarivo (right), central east Madagascar. Photos by Lars-Göran Dahlgren.