For a variety of reasons, breastfeeding is just not possible for everyone. Formula was a lifesaving development when it was first created. Before formula, a lot of babies who did not have access to adequate breast milk starved to death.
Sometimes wet nurses provided babies with nourishment, if their mothers could not, or did not want, to breastfeed. These were usually women who earned an income by breastfeeding other women’s babies. In some cultures around the world, even today, milk sharing is a socially accepted practice among sisters and close friends who support each other by feeding a baby if the mother cannot produce enough milk.