The bone fragments were previously believed to be among the oldest human fossils discovered in Japan.
The 20,000-year-old fossilized remains known as “Ushikawa Man,” once considered among Japan’s oldest human fossils, have now been reidentified, with new research revealing they belong to an ancient bear instead.
The fossils were discovered in the late 1950s in Toyohashi, approximately 140 miles (225 kilometers) southwest of Tokyo. However, Gen Suwa, an anthropologist at the University of Tokyo who led the new study, told that skepticism about the Ushikawa fossils first emerged in the late 1980s and has persisted ever since. The study, published on December 1, 2024, in Anthropological Science, conclusively demonstrates that the bones are from an ancient brown bear, Suwa confirmed in an email.
Suwa explained that bear bones from this period are rarely found in Japanese archaeological sites, leading early researchers, including the paleontologists who unearthed the fossils, to have a limited understanding of what bear bones looked like. Nevertheless, these scientists had made “detailed and very accurate” observations, collecting extensive fossilized skeletal remains over several decades.
The fossils, named after the Ushikawa district in Toyohashi where they were excavated between 1957 and 1959, were initially thought to be human remains. At the time, Japanese scientists believed another fossil, “Akashi Man,” to be the earliest human remains from mainland Japan, dating back more than 780,000 years. However, this fossil was destroyed in an Allied air raid during World War II. In the 1980s, an analysis of a plaster cast of the lost Akashi fossil suggested that it might have been a fragment of a more recent human arm bone, mineralized after being washed into a different archaeological layer. This led to renewed attention on the Ushikawa fossils, Suwa noted.
The initial description of the Ushikawa fossils included a humerus bone from the upper arm and the head of a femur from the leg of a human who lived more than 20,000 years ago. However, the new study, using visual inspection and CT scans, found that the humerus was likely the radius from the forearm of a brown bear (Ursus arctos), and the femur head also came from a bear.
With this reidentification, the oldest confirmed human fossils on the Japanese mainland are now fragments of a human leg bone, arm bone, collar bone, and skull found in a limestone quarry near Hamakita, about 25 miles (40 kilometers) east of Ushikawa. These remains, believed to belong to two individuals, date to roughly 14,000 and 17,000 years ago.
Additionally, human fossils have been discovered on Japan’s Ryukyu Islands (Nansei Islands), situated between Japan and Taiwan. Scientists estimate that the youngest of these fossils are about 18,000 years old, with some of the oldest potentially dating back as far as 32,000 years.
This recent finding is not the first case of confusion between human and bear bones. In the 1990s, a bone discovered in an Alaskan cave was initially thought to be from a bear, but later research revealed it to be from a Native American woman who lived around 3,000 years ago.
