 Penghu 1 on display | |
| Common name | Penghu 1 |
|---|---|
| Species | Homo, species uncertain |
| Age | c. 100,000 years[1] |
| Place discovered | Taiwan Strait, Pacific Ocean |
| Date discovered | before 2008 |
Penghu 1 is a fossil jaw (mandible) belonging to an extincthominin species of the genusHomo. It was collected from seafloor sediments of thePenghu Channel off the coast ofTaiwan, dating to sometime in theMiddle Pleistocene orLate Pleistocene. The precise classification of the mandible is disputed. Some believe it to be the fossil of aH. erectus, an archaicHuman or possibly aDenisovan.
The fossil was recovered sometime before 2008 by fishermen working in thePenghu Channel between thePenghu Islands and mainlandTaiwan and acquired byTainan citizen Kun-Yu Tsai.[1] The fossil was found 60–120 meters below the water's surface and about 25 kilometers off the western coast of Taiwan in an area which was once part of the mainland. Sea levels have risen since the last ice age and in consequence have submerged the area where the fossil was recovered.[2] After Tsai donated the fossil to theNational Museum of Natural Science, it was described in 2015 by an international team of Japanese, Taiwanese, and Australian scientists.[1]
Penghu 1 is currently housed at theNational Museum of Natural Science inTaichung.[1][3]
The fossil is stratigraphically dated to younger than 450kya, based on prehistoric sea-level lowering to either between 190 and 130 kya, or to between 70 and 10 kya.[1]
The fossil consists of a nearly complete right lower jaw with four teeth, including wornmolars andpremolars.[1] Themandible has a high index of robustness, a robust lateral torus, large molars, and with the help of3D reconstruction it was revealed to have a large bicondylar breadth.[4] These features help confirm that the fossil was from the middle-late Pleistocene era.[4] The alveoli of its four incisors and right canine have been preserved as well showing their great length. The specimen was assigned to the genusHomo based on its jaw and tooth morphology. The mandible shows a receding anterior surface and lacks a pronounced chin which has helped distinguish it from the speciesHomo sapiens. However, the fossil exhibited derived traits similar to earlyHomo habilis including the shortness and width of its jaw. These and other characteristics such as the agenesis of the M3 molar have been sufficient evidence to classify the specimen of the genusHomo.[1]
Although the genus of the Penghu 1 has been widely accepted, there is much discussion on the potential species of the specimen. The Penghu 1 mandible has been described as most similar toHexian fossils ofHomo erectus. Both Penghu 1 and the Hexian mandible share a similar crown size, mandibular prominence, and general robustness.[5] As a result of these similarities and their late presence in Eastern Asia, the authors of "The first Archaic Homo of Taiwan"[1] proposed several models for their existence. The features the mandibles' shared could be explained by either the retention of primitive characteristics of early AsianHomo erectus, a migration ofHomo with robust jaws from Africa, inclusion in the speciesHomo heidelbergensis, or they could have been an adapted form ofHomo erectus.[1] However, the species identity or taxonomic relationships lack consensus due to limited material.[1] Co-author Yousuke Kaifu cautioned that additional skeletal parts are needed before species evaluation.[2] In 2015, paleontologistMark McMenamin argued that unique dental characteristics of the jaw were sufficient to establish a separate species, which he dubbedHomo tsaichangensis.[6] In a 2015 paper,Lelo Suvad accepted the validity of the new speciesH. tsaichangensis.[7] Chinese anthropologistsXinzhi Wu and Haowen Tong did not agree with the naming of a new species, tentatively assigning the mandible toarchaicHomo sapiens, leaving open the possibility of elevating it to a distinct species should more fossils be discovered.[4]
In 2019,Chen Fahu along with a group of co-authors presented a piece suspecting the Penghu 1 mandible to belong to aDenisovan.[8] This conclusion has been supported through its comparison with the DenisovanXiahe mandible. The Xiahe mandible was discovered on theTibetan Plateau and is dated to be around 160,000 years old. The Xiahe specimen has similar dental morphology compared to Penghu 1. They share 4 distinct characteristics: their M2's are close in mesiodistal width, they both show the agenesis of the M3 molar, they have a similar unique M2 root structure which relates to modern Asian populations, and the P3 displays Tomes' root, which is rarely found in other fossil hominins.[8]
Wu & Bae (2024) assigned Penghu 1 to the new speciesHomo juluensis, as Xujiayao hominin, Xiahe mandible and Denisovans.[9]
Older low-sea-level events, 225, 240–280, ?300, 335–360 and 425–450 ka cannot be completely excluded as the age for Penghu 1, but such a situation requires explanation for preservation through repeated sedimentary events and the unusual distribution ofCrocuta crocuta ultima. Therefore, Penghu 1 is younger than 450 ka, and most likely 10–70 ka or 130–190 ka.
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