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 to Hexian fossils of Homo erectus. Both Penghu 1 and the Hexian mandible share similar crown size, mandibular prominence, and general robustness. As a result of these similarities and their late presence in Eastern Asia, the authors of "The first Archaic Homo of Taiwan" proposed several models for their existence. The features the mandibles' shared could be explained by either the retention of primitive characteristics of early Asian Homo erectus, a migration of Homo with robust jaws from Africa, inclusion in the species Homo heidelbergensis, or they could have been an adapted form of Homo erectus. However, the species identity or taxonomic relationships lack consensus due to limited material. Co-author Yousuke Kaifu cautioned that additional skeletal parts are needed before species evaluation, but paleontologist Mark McMenamin argued that unique dental characteristics of the jaw were sufficient to establish a separate species, which he dubbed Homo tsaichangensis. McMenamin compares Penghu 1 to Gigantopithecus jaw fragments found in Semedo Village in Central Java, insisting on their relationship being a case of convergent evolution. He refers to these fragments as Gigantopithecus cf. G. blacki, (in this case cf. means that the fragments probably belongs to the species Gigantopithecus blacki, but it is possible that they belong to some other, yet undescribed, Gigantopithecus species) and he explains that this genus was once deemed similar to Homo and Australopithecus until later being recognized as a giant pongid.
