However, human fossils from that era have not yet been discovered because the Japanese archipelago is covered with volcanic ash and has acidic soil due to its many volcanoes, which makes fossils difficult to retain.
ただし、火山を多く持つ日本列島は火山灰に覆われており、土壌が酸性であるため化石が残りにくい事から、この時代の人類の化石は未だに発見されていない。