Scientists build stone age canoe to solve ancient mystery

By Stephen Beech

Researchers built a dugout canoe using only stone tools and paddled it 140 miles across treacherous seas to show how people migrated 30,000 years ago.

Inspired by Norwegian explorer Thor Heyerdahl's 1947 Kon-Tiki expedition, scientists retraced the routes of early modern humans in East Asia using just the technology available at the time.

They explained that when and where the earliest modern human populations migrated and settled in East Asia are relatively well known.

But how those people moved between islands across "dangerous" stretches of sea had remained a mystery.

Researchers from Japan and Taiwan, led by Professor Yousuke Kaifu from the University of Tokyo, simulated methods ancient peoples would have needed to accomplish such journeys.

The team used period-accurate tools to create the canoes to make the journey themselves.

Evidence suggests that around 30,000 years ago, humans made a sea crossing - without maps, metal tools or modern ships - from what is now Taiwan to some of the islands in southern Japan, including Okinawa.

To find out exactly how this crossing was made, Kaifu's team first used numerical simulations to cross one of the strongest currents in the world, called the Kuroshio.

The simulation showed that a boat made using tools of the time, and the right know-how, could have navigated the Kuroshio.

The team built a 24-foot (7.5-metre) dugout canoe, called Sugime, from a single Japanese cedar trunk, using replicas of 30,000-year-old stone tools.

They then paddled it 140 miles (225 km) from eastern Taiwan to Yonaguni Island in the Ryukyu group, navigating by only the sun, stars, swells and their instincts.

The team paddled for over 45 hours across the open sea, mostly without any visibility of the island they were targeting.

Now, six years later, the researchers are still unpicking some of the data from the daring experiment.

Kaifu said: “We initiated this project with simple questions: ‘How did Palaeolithic people arrive at such remote islands as Okinawa?’ ‘How difficult was their journey?’ 'And what tools and strategies did they use?’

“Archaeological evidence, such as remains and artefacts, can’t paint a full picture as the nature of the sea is that it washes such things away.

"So, we turned to the idea of experimental archaeology, in a similar vein to the Kon-Tiki expedition of 1947 by Norwegian explorer Thor Heyerdahl.”

He added: “A dugout canoe was our last candidate among the possible Palaeolithic seagoing crafts for the region.

"We first hypothesised that Palaeolithic people used rafts, but after a series of experiments, we learned that these rafts are too slow to cross the Kuroshio and are not durable enough.

“We now know that these canoes are fast and durable enough to make the crossing, but that’s only half the story.

"Those male and female pioneers must have all been experienced paddlers with effective strategies and a strong will to explore the unknown.

"We do not think a return journey was possible. If you have a map and know the flow pattern of the Kuroshio, you can plan a return journey, but such things probably did not take place until much later in history.”

To understand whether such a journey could have been made in different circumstances, the researchers also used advanced ocean models to simulate hundreds of virtual voyages.

The simulations tested varying starting points, seasons and paddling methods under both modern and ancient ocean conditions.

Dr. Yu-Lin Chang, lead author of one of two papers from the study published in the journal Science Advances, said: “I major in oceanography and use numerical methods and particle tracking techniques to research things like eel and salmon migrations, pumice drift after volcanic eruptions, and oil spills in the Gulf of Mexico.

“The Kuroshio Current is generally considered dangerous to navigate.

"I thought if you entered it, you could only drift aimlessly.

"But the results of our simulations went far beyond what I had imagined.

"I’m pleased this work helped illuminate how ocean voyages may have occurred 30,000 years ago.”

The research team said the simulations helped fill gaps that a one-time experiment could not.

They revealed that launching from northern Taiwan offered a better chance of success than from further south, and that paddling slightly south-east rather than directly at the destination was "essential" for compensating against the powerful current.

The researchers say the findings suggest a "high level" of strategic seafaring knowledge among early modern humans.

Kaifu said, “Scientists try to reconstruct the processes of past human migrations, but it is often difficult to examine how challenging they really were.

"One important message from the whole project was that our Palaeolithic ancestors were real challengers.

"Like us today, they had to undertake strategic challenges to advance. For example, the ancient Polynesian people had no maps, but they could travel almost the entire Pacific."

He added: "There are a variety of signs on the ocean to know the right direction, such as visible land masses, heavenly bodies, swells and winds.

"We learned parts of such techniques ourselves along the way.”