In the past, tohunga (learned experts) were a special group of people. They were selected at birth, usually from the rangatira class, although particularly talented individuals might be selected from lower ranks. The most revered were the tohunga ahurewa who were trained in a whare wānanga (school of learning) and whare tātai (school of genealogy). They understood genealogy, oral history, astronomy, natural lore and a large repertoire of chants and karakia (prayers and incantations) for planting, felling trees, building houses and canoes, making war, healing the sick, and farewelling the dead. Tohunga mākutu, trained in the whare-maire (house of learning), was believed to have the ability to mākutu, that is, cast spells to make people sick or to kill them. Other kinds of tohunga included tohunga whakairo (carvers), tohunga tārai waka (canoe builders), tohunga tāura (apprentice tohunga), tohunga tohiora (experts in birthing) and tohunga tā moko (tattoo artists).