Archaeologists have uncovered the oldest known evidence of human presence on the Indonesian island of Sulawesi, raising new questions about who these early people were and how they got there.
The discovery was made by researchers from Griffith University and Indonesia’s National Research and Innovation Agency (BRIN), who found stone tools dating back at least 1.04 million years.
The stone tools were excavated at a site called Calio in southern Sulawesi.
Today, it’s a quiet cornfield, but during the Early Pleistocene—or Ice Age—it would have been part of a river valley where early humans made tools, possibly hunted, and carried out other daily tasks.
The tools are sharp-edged stone flakes, likely chipped from river pebbles nearby.
To confirm the age of the site, the team used a combination of paleomagnetic dating (which analyzes changes in Earth’s magnetic field stored in rocks) and direct dating of a pig fossil found near the tools.
This confirmed that early humans were active in Sulawesi at least 1.04 million years ago—earlier than previously believed.
Until now, the oldest known signs of human activity in this part of the world, a region called Wallacea, came from a site on the island of Flores, where similar tools were dated to 1.02 million years ago.
Other evidence from Sulawesi showed human presence around 194,000 years ago, and even farther north in the Philippines, on Luzon island, fossils date to about 700,000 years ago.
This new discovery pushes back the timeline for human arrival in Sulawesi and strengthens the theory that ancient humans made long-distance sea crossings to settle in the islands beyond the Wallace Line.
This invisible boundary separates Asian and Australian wildlife regions and marks a major biogeographical divide. Crossing it would have required significant seafaring ability, even by early human standards.
However, no human bones have been found at the Calio site, so the identity of these tool-makers remains unknown.
Were they Homo erectus, the early human species thought to have crossed into other Wallacean islands like Flores? Or did an entirely different hominin group arrive and evolve in isolation?
The discovery echoes the famous case of Homo floresiensis, or the “hobbit,” a small-bodied ancient human species found on Flores.
Some scientists believe these hobbits were descended from Homo erectus who became smaller over time due to island isolation.
But Sulawesi is much larger than Flores—over 12 times the size—and far more ecologically diverse. This raises new questions: If early humans lived in isolation there for over a million years, did they also evolve into something unique? Or did their story unfold in an entirely different way?
For now, the answers remain buried. But with every new find, scientists come closer to understanding the mysterious early humans who once called Sulawesi home.
