Track of the logboat colored by day (red) and night (light blue). The circle indicates the area from where the Yonaguni Island is visible from a boat when the weather is clear. (Base map by Google Earth, Phtograph by Yousuke Kaifu.)
Four male and one female paddlers put out to sea of Taiwan with a 7.5 m-long logboat (dug-out canoe) made by stone axes. This was an experimental voyage to uncover the challenges Palaeolithic seafarers met when they migrated to the Ryukyu Islands, southwestern Japan, about 35,000 years ago. The team crossed the Kuroshio, one of the strongest ocean currents in the world, and finally found the Yonaguni Island which had been below the horizon and invisible for most of their journey. After the 45 hours of paddling, they successfully reached to this westernmost island of the Japanese Archipelago. See ref. 1 for more information.
Fig. 1. Major Palaeolithic sites of the Ryukyu Islands. The numerals indicate ages (years ago). (Base map by Hironobu Kan based on Gebco 08 Grid)
Fig. 2. Inferred palaeogeography around the Ryukyu Islands about 35000 years ago. The gray areas were lands due to the sea-level lowering. The course of the present-day Kuroshio is indicated. (Base map created by GeoMapApp)
Fig. 3. Test voyages we made in 2016 (reed-bundle raft) and 2017 (bamboo raft). These watercrafts failed to reach their goals (Iriomote Is and Green Is, respectively). (Base map by Hironobu Kan based on Gebco 08 Grid; Photography by Yousuke Kaifu)
The development of seafaring around 50,000 years ago opened up new environments for Homo sapiens beyond the continental landmasses (ref. 2). New evidence now indicates that Homo sapiens had crossed challenging straits with strong ocean current and reached to remote islands that were invisible from their departure points by ~35,000 years ago in the seas of the Ryukyu Islands, southwestern Japan (Figs. 1 and 2) (refs. 3-5).
However, maritime technology used for these voyages remain a matter of conjecture, not least because of the lack of physical evidence of earliest watercrafts. Furthermore, we still do not know the actual challenges of these Palaeolithic voyages, and how people overcame such difficulties with Palaeolithic technology. With the aim to approach these mysteries, this experimental project was planned in 2013 by Dr. Yousuke Kaif, an anthropologist at the National Museum of Nature and Science in Tokyo, and formally initiated in 2016 by a succeed in crowdfunding (refs. 6,7).
The project is run by more than 60 researchers from various fields of science, marine explorers, and management staffs from Japan, Taiwan, and New Zealand. The team plan to build and to test three candidates of the Palaeolithic seagoing crafts, a reed-bundle raft, a bamboo raft, and a logboat. After a series of experiments and tests on the sea (Fig. 3), we choose one of them and carry out the “final experimental voyage” departing Taiwan and head for the Yonaguni Island of Japan.
We also examine various related issues including the palaeogeography, ocean current of that time, population size required for successful migration, and presence or absence of sailing technology, in order to make the project “holistic re-enactment” as far as possible.
Fig. 4. Reed-bundle rafts we made in 2016 with the male and female paddlers. (Photography by Danee Hazama)
We build two reed-bundle rafts by tying reed-mace (Typha domingensis Pers.) using cane (Flagellaria indica L.) (Fig. 4). Both species grow naturally on the Yonaguni Island. In July of 2016, we tested them in the ocean, but the two rafts were drifted by the ocean current and we failed to reach the Iriomote Island (Fig. 3).
Under a collaboration between Japan and Taiwan, we constructed and tested two different designs of bamboo-raft boats (Fig. 5). Although they showed excellent stability, their speed was not enough to cross the Kuroshio current (Fig. 3). The bamboo culms were susceptible to cracking and lacked durability. See ref. 8 for more information.
Fig. 6. Experimental test to cut down a big tree by replicated Palaeolithic tools. (Photography by Yousuke Kaifu)
Our experiment of replicated Palaeolithic edge-ground stone axes, which are known from Japan as old as 38,000 years ago, showed that these tools are useful to cut down a one-meter thick tree and hew a logboat (Fig. 6). We tested the logboat in the seas of Japan and found that it is faster and more durable compared to the reed rafts and bamboo rafts we tested previously.
The above tests and other evidence (ref. 8) strongly suggest that logboats were used as seagoing vessels by the first Ryukyu islanders. We decided to use this model, and paddle our logboat from Taiwan to the Yonaguni Island with the aim to reenact one of the earliest voyages to enter the Japanese archipelago (Fig. 7). This is a big challenge because we have to cross the Kuroshio, and the target island is invisible until the end of the journey. We would have to depart from the south considering the effect of the Kuroshio. In order to experience the challenges the Palaeolithic voyagers confronted, the male and female paddlers do not bring modern navigation tools such as compasses, maps, GPS, smartphones, watches, etc. They have to complete the voyage without replacement, and would be allowed for only a short sleep during navigation.
Organizer：National Museum of Nature and Science, Japan
Co-Organizer：National Museum of Prehistory, Taiwan
Cooperation：Yonaguni Town, Yonaguni Town Board of Education, Ishigaki City, Ishigaki City Board of Education, Taketomi Town, Taketomi Town Board of Education, Okinawa Prefectural Museum & Art Museum, Tokyo University of Marine Science and Technology, Tokyo Metropolitan University
Supporters：Okinawa Prefecture, Okinawa Prefectural Board of Education, Japan-Taiwan Exchange Association