Humans May Have Crossed from Taiwan to Yonaguni 30,000 Years Ago; Strategically Navigated Currents Following Sun, Stars

The Yomiuri Shimbun

13:52 JST, June 29, 2025

It is possible Paleolithic humans in a rowboat were able to cross from Taiwan to Yonaguni Island, Okinawa Prefecture, 30,000 years ago, according to an analysis by a research team.

The team conducted an experimental voyage using a wooden boat. As a result, they found travel across the sea would have been possible, depending on the skill of those in the boat. The result was published in the scientific journal Science Advances.

Japanese ancestors are thought to have arrived from the continent via three routes: Hokkaido, Tsushima Island and the Ryukyu Islands. Arrival via the Ryukyu Islands route is believed to have taken place around 35,000 to 30,000 years ago during the late Paleolithic period. However, as Taiwan and Yonaguni Island are separated by the Kuroshio current, a strong ocean current with a speed of 1 to 2 meters per second, how they crossed the sea had been a mystery.

In 2019, the research team from the National Museum of Nature and Science and other institutions conducted a 225-kilometer experimental voyage in a wooden boat made from a hollowed-out cedar tree. Five paddlers departed from the east coast of Taiwan and reached Yonaguni Island in 45 hours, navigating based on the position of the sun and stars.

Later, the Japan Agency for Marine-Earth Science and Technology and others used a supercomputer to perform numerical simulations to investigate the conditions 30,000 years ago and found the Kuroshio current was 10%-20% faster than today.

Based on the results of the experimental voyage, the research team conducted a hypothetical test with the boat having a maximum speed of 1.08 meters per second, and, taking into account the flow of the current, found the probability of a successful voyage would increase if the boat was paddled at an angle slightly against the Kuroshio current.

“We have discovered our ancestors were strategic explorers who understood the effects of ocean currents and used their skillful navigation techniques to cross the sea,” said University of Tokyo Prof. Yosuke Kaifu, head of the research team.