Experimental archaeology reveals how Paleolithic humans may have crossed deadly ocean currents—without maps, metal tools, or even sight of their destination.
A new study led by researchers from the University of Tokyo and their Taiwanese collaborators is providing unprecedented insight into how early humans may have migrated across open seas tens of thousands of years ago. Through a combination of cutting-edge ocean simulations and hands-on experimental archaeology, the team reconstructed what could have been one of the most dangerous sea crossings in human prehistory—navigating from Taiwan to the Ryukyu Islands of Japan some 30,000 years ago.
Their findings, published in Science Advances, offer compelling evidence that ancient people possessed not only the tools, but the seafaring skills and strategic knowledge needed to cross one of the world's strongest ocean currents: the Kuroshio Current.
How Did Paleolithic Humans Reach Okinawa?
Archaeological evidence suggests humans made the journey from Taiwan to Japan’s southern islands—such as Yonaguni and Okinawa—during the late Paleolithic. But exactly how they did it remained a mystery. Unlike migrations over land, open-water crossings erase the physical evidence: no footprints, no trail of tools, and no sunken boats to study.
That’s why Professor Yousuke Kaifu and his team turned to experimental archaeology—a research approach that involves recreating and testing ancient tools, techniques, and voyages to answer questions traditional archaeology can’t.
Building a 30,000-Year-Old Boat by Hand
In 2019, the researchers constructed a 7.5-meter-long dugout canoe using only replica stone tools consistent with those used by Paleolithic people. The canoe, named Sugime, was carved from a single Japanese cedar trunk and built using labor-intensive, period-accurate methods.
Armed with nothing but paddles, their instincts, and celestial navigation, the team paddled Sugime 225 kilometers from eastern Taiwan to Yonaguni Island—across open sea and without sight of land for most of the 45-hour journey.
"We wanted to understand how difficult this journey was, and what tools and strategies ancient humans might have used," said Kaifu. "The sea doesn’t preserve clues, so we recreated the experience ourselves."
Simulating Ancient Sea Crossings
In tandem with the real-life voyage, a second part of the study focused on numerical ocean simulations. Researchers used particle-tracking models to simulate hundreds of hypothetical voyages under both modern and ancient ocean conditions. Variables such as launch location, season, and paddling direction were tested to determine which strategies would give early humans the best chance of survival.
Their simulations revealed that launching from northern Taiwan gave a much higher success rate, and that paddling slightly southeast, rather than directly toward the islands, helped compensate for the pull of the Kuroshio Current.
"The Kuroshio is a powerful, often dangerous current," said Yu-Lin Chang, oceanographer and lead author of the modeling paper. "But our results showed that with the right approach, even Paleolithic voyagers could use it to their advantage."
What This Says About Our Ancestors
These findings reshape the way we think about early humans—not as aimless wanderers, but as skilled seafarers and strategic explorers.
"They didn’t just drift across the sea by accident," Kaifu emphasized. "They likely had paddling expertise, deep environmental knowledge, and the courage to venture into the unknown—without knowing if they'd ever return."
In fact, the researchers believe return trips were unlikely, as the necessary navigation techniques and understanding of ocean patterns likely developed much later in history.
Challengers of the Paleolithic Sea
This research echoes the spirit of other pioneering maritime cultures, such as the ancient Polynesians, who also used stars, swells, and natural signs to cross vast distances without maps or compasses.
“Humans have always been challengers,” Kaifu said. “Even 30,000 years ago, people were willing to brave the sea and seek out new lands.”
Why It Matters Today
The combination of experimental archaeology and computational oceanography creates a powerful toolkit for uncovering human history. It bridges the gap between what we know from artifacts and what we can only imagine from logic.
"This kind of interdisciplinary work helps us understand migration as more than just movement—it's a story of innovation, adaptability, and endurance," said Chang.
And perhaps, it’s a reminder that even tens of thousands of years ago, humanity's instinct to explore the unknown was already alive and well.
