Wallacea = group of mainly Indonesian islands separated by deep-water straits from the Asian and Australian continental shelves. Wallacea includes Sulawesi, the largest island in the group, as well as Lombok, Sumbawa, Flores, Sumba, Timor, Halmahera, Buru, Seram, and many smaller islands. The islands of Wallacea lie between the Sunda Shelf (the Malay Peninsula, Sumatra, Borneo, Java, and Bali) to the west, and the Sahul Shelf including Australia and New Guinea to the south and east.
Ancient genomes from the last three millennia support multiple human dispersals into Wallacea 🧬🇮🇩🌏 Cool paper - well worth a thread.
16 genomes were sampled in Wallacea, spanning a temporal range of ~2600 to ~250 years before present (YBP). The oldest sample is from Liang Bua on Flores, the same cave where H. floresiensis was discovered. Samples came from NTT, Sulawesi and the North Moluccas.
The Austronesian admixture in Wallacea is estimated to have begun ~3,000 YBP, consistent w/ archaeology, though the data suggest successive waves of migration & admixture that complicates estimates from newer samples. Perhaps older samples might yield even earlier dates…?
The authors suggest most of the Denisovan admixture in Wallacea arrived via back-migration from New Guinea, and show that it’s correlated with the level of Papuan ancestry. Very interesting, and more evidence to support the notion that PNG was the Denisovans’ final refuge.
Finally - this was especially fascinating - even the earliest sample from NTT (the 2,600 YBP Liang Bua individual) had substantial admixture with mainland Southeast Asia, suggesting a very old migration from the mainland to the Sundas, but not to the Moluccas.
The oldest evidence of contact between these regions prior to this was was from the Dong Son drums (like the ones at the Mataram museum earlier this week), dating from nearly a millennium later than the Liang Bua sample. One final interesting finding is that the individuals studied were genetically more similar to present-day Papuans than to the mid-Holocene Wallacean genome published in August, despite being from the same region. The identity of these more ancient Wallaceans remains an enigma.