Until the 1700s in Europe, and more recently in some countries, there was a custom to castrate young male slaves and boys. Young slaves were castrated so that they could be used as guards over the wives of rich men. It meant that the wives would not fall in love with their guards. Sometimes young boys who had beautiful singing voices were castrated before puberty. This meant that their voices would stay high all their lives. These singing men were called castrati. 