Ukusetyenziswa kwee-metals kuthiwa yinto eyenza ukuba abantu bohluke kwizilwanyana. phambi kokuba basebenzise ii-metals, abantu benza ii-tools zamatye, iinkuni, akunye namathambo ezilwanyana. Zizo ezi kungoku nje zibizwa ngokuba zii-Stone Age.