Although Madagascar is geographically closer to the southeast coast of Africa, this large island nation has stronger genetic and cultural ties to island peoples thousands of miles away in Southeast Asia. There, the people speak a family of languages known as Austronesian, which includes Malagasy, the language spoken in Madagascar. Archaeologists have struggled, however, to find on-the-ground evidence connecting Madagascar’s mysterious settlers directly to Southeast Asia.
To search for such evidence, an international team of archaeologists led by Alison Crowther of the University of Queensland, Australia, took a novel approach by investigating domesticated plants, which settlers often bring with them. The researchers excavated eighteen sites across Madagascar, nearby islands, and coastal East Africa, sifting through sediments for signs of ancient crops. Previous archaeological evidence indicates that human settlements had been established at these sites between 650 and 1200 CE, and geneticists and linguists estimate that Southeast Asians arrived on Madagascar around that time. The team dated and identified the remains of almost 2,500 crop plants, which were preserved by charring during such activities as cooking and burning garbage.
After examining these crops’ origins, the team found a distinct geographic split. On eastern mainland Africa and nearshore islands, African crops such as millet and sorghum were much more common than Asian crops, which likely arrived later with commercial trade. On Madagascar and the small neighboring islands of the Comoros, however, Asian crops—namely rice and mung bean—dominated even the early archaeological record, in the eighth to tenth centuries CE.
The ancient remains of rice and mung bean add archaeological support for the idea that Southeast Asian islanders colonized Madagascar and, unexpectedly, the Comoros, whose people speak an African language. “The finding of mainly Asian cultivars in sites on the Comoros took us by surprise,” says Crowther, “because, unlike Madagascar, which has very clear linguistic, biological, and cultural affinities with Southeast Asia, such links are not as clear in the Comoros today.” Additional studies will be needed to determine how the Comoros fi gures into the Southeast Asian migration westward. (Proceedings of the National Academy of Sciences)