The origin of the character "Yu (育)" has been a long-standing and unsolved problem. In the past, it was thought that "Yu (育)" was a simplified form of the character "Yu (毓)", or that "Yu (育)" was another variant of "Yu (毓)". However, these assumptions are not appropriate. Through extensive investigations of ancient Chinese characters, it is known that before the Han Dynasty, "Yu (育)" borrowed the character "Zhou (胄)" as its graph. From the Han Dynasty onwards, "Yu (育)" gradually differentiated from the character "Zhou (胄)", and "Yu (育)" became a variant of the character "Zhou (胄)".