The position has been used at least for millennia if not longer since it is also used by the great apes, as well as other primates. Robert Francoeur notes that evidence of the missionary position's use appears in ancient pottery and art in the Fertile Crescent as well as in the art of Early Greeks, Romans, Peruvians, Indians, Chinese and Japanese. The majority of the positions described in the Kama Sutra involve the woman lying on her back with her legs in a variety of positions. According to Canongate, ancient art shows missionary as being less popular than woman-on-top positions in Ur, Greece, Rome, Peru, India, China and Japan. But Francoeur states that the ancient Chinese preferred male-on-top because of their belief that males are born face down and women face up. Kagaba natives in Colombia preferred missionary because of the stability it offers; they believed that if the woman moved during intercourse, the earth would slip off the shoulders of the four giants who held it up above the waters. Some Kerala tribes believe that the male-on-top position is the only way to conceive warriors.