Mark W. Moore, University of New England

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Mysterious human form was the first in Wallacea

16.8.2025

Translation: machine translated

Early humans ventured across the sea in the Wallacea earlier than previously thought. They reached the south-east Asian island of Sulawesi at least 1.04 million years ago.

The ancestors of modern humans probably crossed the deep sea at the Wallace Line to reach the island of Sulawesi earlier than previously assumed. At least 1.04 million years ago, if not already 1.48 million years ago, they ventured onto the large island in what is now Indonesia. This was the result of an analysis of stone tools discovered on Sulawesi by Budianto Hakim from the Indonesian National Research and Innovation Agency in Jakarta, Adam Brumm from Griffith University in Brisbane and their team and presented in «Nature».

The oldest evidence to date that early humans had crossed the Wallacea - the transitional area at the faunal and floral boundary with Australia - comes from the Indonesian island of Flores. The region is known for the fossils of the small Homo floresiensis or «hobbit man», who lived on the island until around 50,000 years ago. However, the oldest stone tools from there date back around 1.02 million years. Stone artefacts from the Philippine island of Luzon, which was home to its own dwarf-like human form called Homo luzonensis, also testify to the presence of humans around 777,000 years ago. In contrast, only much younger artefacts have been found from Sulawesi: The earliest tools show an age of 194,000 years.

Hakim, Brumm and their colleagues have now discovered seven stone tools in a sediment layer at the Calio site in the south of Sulawesi, which they date to between 1.04 and 1.48 million years ago using palaeomagnetics and uranium-thorium dating of fossilised animal teeth. This means they could be older than all artefacts from Flores and Luzon - or at least just as old as the earliest finds from Flores.

The hominins who once used their tools by a river in Calio may therefore have been among the very first members of their species to leave the deep sea trench of Wallacea behind and venture into terra incognita. However, the researchers do not know how they did this.

What form of human they were is also still unknown. Around 700,000 years ago, the ancestors of the «hobbit people» most certainly roamed Flores, as the fossil discovery by a research team including Brumm 2024 proved. No fossils of human bones have yet been recovered in Calio. The exact identity of the presumed pioneers is therefore still unclear. However, it is plausible that in this phase of the Pleistocene they were members of the human form Homo erectus.

The Wallace Line runs as a deep sea trench between the islands of Sulawesi and Borneo as well as Lombok and Bali. Even during the ice age when sea levels fell, no land bridges formed there. This is why the animal world is divided along the Wallace Line. Typical Australian species such as kangaroos and koalas live south-east of this line, but are never found beyond it, i.e. north-west of it. On the other hand, no monkeys or elephants have become native to the wilderness on the Australian side.

Spectrum of Science

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Original article on Spektrum.de

Header image: Mark W. Moore, University of New England

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