Aka ahu bu mkpagara-ahu adiji enwere he. Ndi mmadu ma ndi anumanu nke ana-kpo primates nwere aka abuo, aka nke aka-nri ma aka-ikpa. Aka anyi kwesiri nwe mkpisi-aka ru ise. Mgbe ufodu, onye mmadu nwere ike inwe aka nke gbajiri n'eweghi mkpuru-aka ruru ise. Mgbe ufodi, anumanu nke enweghi aka ne nwe onu wo jide he.