Penghu 1

Penghu 1 is a fossil lower jaw from an extinct member of the genus *Homo*. It was pulled from seafloor sediments in the Penghu Channel, off Taiwan’s coast, and dates to the Middle or Late Pleistocene. For years, scientists disagreed on its classification, but a 2019 proteomic study identified Penghu 1 as likely Denisovan, though not specifically as male.

The jaw was recovered before 2008 by fishermen working between the Penghu Islands and mainland Taiwan, about 25 kilometers offshore and 60–120 meters underwater. The area, once dry land, was submerged after the last ice age. A Tainan resident named Kun-Yu Tsai acquired the fossil and later donated it to the National Museum of Natural Science in Taichung. An international team of Japanese and Taiwanese scientists described it in 2015. Based on prehistoric sea levels, the fossil is stratigraphically dated to younger than 450,000 years ago, with possible age ranges of 190,000–130,000 or 70,000–10,000 years ago.

In a 2015 paper, Mark McMenamin proposed the species name *Homo tsaichangensis*, but this name is considered unpublished and unavailable as of 2025. Although the work was registered with ZooBank, the paper itself lacks evidence of that registration, violating ICZN articles 8.5.3.1 and 8.5.3.2. It is also unclear whether multiple identical, durable copies (such as print versions) were ever widely distributed, as required by ICZN article 8.1.3.1.

The fossil is a nearly complete right lower jaw with four teeth—worn molars and premolars. It has a high robustness index, a strong lateral torus, large molars, and, based on 3D reconstruction, a large bicondylar breadth. These traits place it in the middle-late Pleistocene. The alveoli of its four incisors and right canine are preserved, showing their great length. The jaw was assigned to *Homo* based on its shape and teeth. It has a receding front surface and lacks a pronounced chin, distinguishing it from *Homo sapiens*. However, it also shows derived traits similar to early *Homo habilis*, such as a short, wide jaw. Other features, including the absence of the M3 molar, support its classification in the genus *Homo*.

While the genus is widely accepted, the species has been debated. The Penghu 1 jaw is most similar to the Hexian *Homo erectus* fossils, sharing crown size, mandibular prominence, and overall robustness.