The fossilized bones of the so-called Ushikawa Man, once believed to be among the oldest human fossils in Japan, have been identified as the remains of an ancient brown bear. Gen Suwa, an anthropologist at the University of Tokyo who led the new research, confirmed the findings. "The new research shows beyond a doubt that the bones are from an ancient brown bear," Suwa said, according to Live Science.

The Ushikawa fossils were discovered between 1957 and 1959 in Toyohashi, Japan, approximately 225 kilometers southwest of Tokyo. Initially, these bones were identified as a human arm bone (humerus) and the head of a human femur, thought to belong to an individual who lived more than 20,000 years ago. Despite the initial excitement, doubts about the Ushikawa fossils were first raised in the late 1980s and continued since then, leading to the recent confirmation of their true identity.

The misidentification has implications for the understanding of Japanese prehistory. The discovery that the Ushikawa fossils are not human means that the oldest human fossils found on the Japanese mainland come from a limestone quarry near the city of Hamakita, about 40 kilometers east of Ushikawa. These fossils include fragments of human leg bone, arm bone, collarbone, and skull believed to come from two different individuals—one who lived about 14,000 years ago and another who lived about 17,000 years ago.

Japanese paleontologists at the time had limited knowledge of how bear bones appeared, as they were rarely found in archaeological sites of that period. "The confusion may have been caused by the fact that, at the time of the discovery, bear bones were not common in Japanese archaeological sites of that period," reported Scienze Notizie. This lack of familiarity likely contributed to the initial misclassification of the bear bones as human remains.

Despite this, scientists in the 1950s provided "detailed and very accurate" descriptions of the bones and collected large numbers of fossilized skeletal remains over several decades, according to Live Science. However, advancements in technology and methodology now allowed for a more precise identification of such fossils.

This was not the first time that human bones and bear bones were confused. A similar case occurred in Alaska in the 1990s, when a bone thought to belong to a bear was subsequently identified as part of a human bone, dating back about 3,000 years. Such misidentifications underscore the challenges faced in the field of paleoanthropology, especially when dealing with fragmentary or incomplete remains.

The revelation about the Ushikawa fossils also brings renewed attention to other ancient fossils in Japan. Japanese scientists had previously believed that a different bone fragment known as Akashi Man was the oldest human fossil from mainland Japan, possibly over 780,000 years old. However, in the 1980s, an anatomical analysis of a plaster cast of the lost Akashi fossil showed that it was probably a fragment of a recent human arm bone that washed into an older archaeological layer and then mineralized, as reported by Live Science.

Human fossil remains have also been found on Japan's Ryukyu Islands—situated about midway between Japan and Taiwan—with the youngest fossils dating from about 18,000 years ago and the oldest possibly from up to 32,000 years ago. These findings provide valuable insights into the migration and habitation patterns of early humans in the region.

The article was written with the assistance of a news analysis system.