Early Holocene wild boar remains from Tsudupisuki-abu Cave on Miyako Island of the Southern Ryukyus, Japan

Abstract

A large number of Sus remains were recently collected from early Holocene sediments of Tsudupisuki-abu Cave on Miyako Island of the Southern Ryukyus, Japan, during excavations. Wild boar (Sus) are now absent from the island, where Sus remains were also uncommon in Quaternary fossil localities before the excavations. Taxonomic analyses of the Sus remains, especially metrical analysis of third molars, have revealed that the remains are divided into two clusters (A and B) of different size. Cluster A consists of larger specimens and cluster B of smaller specimens and are referred, respectively, to Sus scrofa and Sus sp. On the basis of the information of Sus remains from this cave and another locality (Pinza-abu Cave), we reconstruct a late Quaternary history of Sus on Miyako Island. It is inferred that large-sized Sus scrofa was introduced by humans onto the island in the late Late Pleistocene, and then reduced in size to be Sus scrofa of Tsudupisuki-abu Cave by a mechanism of insular dwarfism until the early Holocene. On the other hand, the second human introduction of a miniature Sus form (= Sus sp.) seems to have taken place in the earliest Holocene.