Young girls generally started working well before boys, with many working before age seven. Although field work was traditionally considered to be "men's work," different estimates conclude that between 63-80 percent of women worked in the fields. Adult female work depended greatly upon plantation size. On small farms, women and men performed similar tasks, while on larger plantations, males were given more physically demanding work. Few of the chores performed by enslaved women took them off the plantation. Therefore they were less mobile than enslaved men, who often assisted their masters in the transportation of crops, supplies, and other materials, and were often hired out as artisans and craftsmen. Women also worked in the domestic sphere as servants, cooks, seamstresses, and nurses. Although a female slave's labor in the field superseded childrearing in importance, the responsibilities of childbearing and childcare greatly circumscribed the life of an enslaved woman. This also explains why female slaves were less likely to run away than men.