Crops growing in Madagascar. Credit: Nicole BoivinIn 2005, a study published in the American Journal of Human Genetics found the human inhabitants of Madagascar can trace their genetic lineages back to two regions, the relatively nearby Eastern Africa and the Southeast Asian island Borneo, around 4,500 miles away.

At the time, the researchers noted that while the Malagasy people’s lineage is roughly a 50-50 split between the two regions, they speak a language derived exclusively from Indonesia.

Now, researchers believe they’ve found archaeological evidence of settlers from Southeast Asia. The study was published in Proceedings of the National Academy of Sciences.

After excavating 18 ancient settlement sites from Madagascar, neighboring islands, and the East African coast, the researchers found remains from nearly 2,500 plant species. Among the plant remains, researchers noticed that on Madagascar, the distribution favored Asian plants, including rice and mung beans. Additionally, the crops from the nearby Comoros Islands were also heavily Asian in origin. The Comoros Islands lie between Madagascar and the Eastern African coast.

“This took us by surprise,” said study author Alison Crowther, of the University of Queensland, in a statement. “After all, people in the Comoros speak African languages and they don’t look like they have Southeast Asian ancestry in the way that populations on Madagascar do. What was amazing to us was the stark contrast that emerged between the crops on the Eastern African coast and those on Madagascar.”

On the coast, and on islands such as Mafia and Zanzibar, the plants included African species, such as sorghum, pearl millet, and baobab.

The researchers postulated the Asian crops were brought to Madagascar and the Comoros Islands by the eighth and tenth century.

“We’ve been able to not only … show for the first time an archaeological signature of Austronesians, we’ve also shown that it seems to extend beyond Madagascar,” said study author Nicole Boivin, of the University of Oxford, in a statement.

Crowther noted that the arrival of inhabitants from Southeast Asia may have coincided with the extinction of Madagascar’s megafauna.