Oldest plant artefact found outside Africa reveals Pacific's role in early human migration

Moses Dailom, team member and study co-author, sorts archaeological material at Mololo Cave. Photo credit: Tristan Russell (The Raja Ampat Archaeological Project).

Despite the Pacific’s critical importance for global population movements, scientists have not yet been able to pin down exactly when and where early humans travelled on their journey into the region. At this time, the Earth was in an Ice Age, meaning that sea levels were lower: the large continental shelves around Asia (called Sunda) and Australia (called Sahul) were exposed as dry land, but many of the islands of Southeast Asia remained islands.

Our species — Homo sapiens — may have moved along a “northern route” from what is now Borneo into Sulawesi, Maluku, and then West Papua, or a “southern route” from present-day Java and Bali to Flores, Timor, and then Australia (see map below). Previous research has hinted that seafarers arrived to Sahul perhaps as early as 65,000 years ago, while other archaeologists insist that these maritime crossings did not take place until after 50,000 years ago.

This new study, carried out on Waigeo Island¹ in West Papua, off the coast of Ice Age Sahul, provides the first detailed evidence for the earliest stage of human arrival along the northern route into the Pacific. The findings demonstrate that Waigeo was an important stepping stone visited by the first seafarers. At this time Waigeo was part of a larger “palaeo-island” which the research team have named Waitanta². This palaeo-island split into a series of smaller islands including Waigeo at the end of the Ice Age, when sea levels rose. Computer modelling and chemical isotope studies carried out by the researchers show that Waitanta contained patches of rainforest and a large valley system, and it was separated from Sahul by a deep-sea strait only a few kilometres wide.

Ancient migration routes from Asia to the Pacific region. Image credit: Dylan Gaffney (The Raja Ampat Archaeological Project).

The team’s excavations at a large cave site called Mololo³, in the interior of ancient Waitanta, uncovered rare evidence for human settlement and behaviour, including animal bones and a small rectangular tree resin artefact. The latter was directly dated at the University of Oxford’s radiocarbon accelerator to show it is 55,000–50,000 years old and the oldest plant artefact made by our species outside of Africa.

The researchers believe the artefact was produced in a multistep process by cutting the bark of a resin-producing tree, allowing it to harden, and then snapping it into shape, possibly to use it as a fuel source for fires inside Mololo cave (see image below). ‘The use of complex plant processing indicates these humans were sophisticated, highly mobile, and able to devise creative solutions to living on small tropical islands’ concluded Professor Daud Tanudirjo of Universitas Gadjah Mada, the co-director of the study.

Modern tree resin artefact used to make fire on Waigeo Island, 2018. Photo credit: Dylan Gaffney (The Raja Ampat Archaeological Project).

The research team are continuing their archaeological research in West Papua, in the form of a large project funded by National Geographic that seeks to understand how early people adapted to the Pacific region and changed their behaviours in response to past climate change. For updates, see raja-ampat-arch.com or follow @DylanGaffneyNZ on Twitter/X.

The study ‘Human dispersal and plant processing in the Pacific 55,000–50,000 years ago’ has been published in Antiquity.

Explanation of place names:

1. Waigeo, meaning the sea inside or the water inside, named for its inland bay.

2. Waitanta, from Wai = water and Tanta = that stretches before your eyes. This is based on the islands of Waigeo and Batanta which were connected during the last Ice Age.

3. Mololo, meaning the place where the currents come together, since it is an area of choppy water and whirlpools.

Tree resin artefact excavated from Mololo Cave, dated to 50,000–55,000 years old. Image credit: Dylan Gaffney (The Raja Ampat Archaeological Project).