During the last ice age, when sea levels were lower, Taiwan’s Penghu Channel was part of the Asian mainland. It was in this area, about 15.5 miles off the coast of Taiwan, that an Taiwanese fisherman dredged up an unusual jawbone. That bone, say researchers, may represent a new species of hominin and indicate that a number of primitive human groups once lived in Asia.

The fisherman who originally discovered the jawbone, now called Penghu 1, to a antique dealer. The dealer sold it to a local collector who recognized the significance of it and turned it over to Taiwan’s National Museum of Natural Sciences.

Now that the fossil has undergone a more thorough examination, researchers believe it to be the first human fossil ever found in Taiwan.

Analysis of the bone, which consists of primitive looking teeth set in the lower right side of a jaw, reveals that the owner probably lived between 10 and 190,000 years ago. However, the teeth look primitive compared to what researchers would expect to find for the era.

Humans gradually evolved to have smaller teeth and jaws during the Pleistocene Epoch which started 2.6 million years ago and ended 11,700 years ago.

Penh 1, say the researchers, most closely resembles a 400,000 year old fossil found in Hexian in southern China. That location is only about 600 miles from the Penghu Channel. This suggests to the scientists that a distinct group of humans may have lived in the region for a very long time.

“We need other skeletal parts to evaluate the degree of its uniqueness. The question of species can be effectively discussed after those steps,” said Yousuke Kaifu a paleoanthropologist at Japan’s National Museum of Nature and Science in Tokyo told Live Science.

Kailua is the co-author of a paper published in Nature Communications.

Asia is known to have been home to at least four extinct species of hominids. These included of Neanderthals, Denisovans as well as Homo erectus who are likely the direct ancestors of modern Homo sapiens. The mysterious hobbit like Homo floresiensis, who lived in Indonesia.

If Pengu 1 represents a new species it would suggest that numerous groups of humans, at various stages of evolution, lived together in the region.

“I have considered the Denisovans as an Asian sister group of the Neanderthals, and like them, derived from Homo heidelbergensis, but if Penghu is indeed a long-awaited Denisovan jawbone, it looks more primitive than I would have expected. As the authors note, this enigmatic fossil is difficult to classify, but it highlights the growing and not unexpected evidence of human diversity in the Far East, with the apparent co-existence of different lineages in the region prior to, and perhaps even contemporary with, the arrival of modern humans some 55,000 years ago,” said Prof Chris Stringer of the Natural History Museum, London who was not involved in the study.

Although there are many theories, it is not definitively known what happened to all of these diverse groups of people. All of them seem to have vanished shortly after the arrival of Homo sapiens.

“This is a very different, complex and exciting story compared to what I was taught in school,” said Kaifu.