The primary ways in which females reliably differ from males have to do with reproduction. In mammals the female produces an egg that is fertilized and nurtured within her body until the fetus is capable of surviving in the outside world. After birth, for periods ranging from weeks to years, young mammals continue to depend mainly on their mothers' milk for food. This chapter concerns the ways in which female mammalian reproduction affects what's eaten, as well as the ways in which what's eaten affects female mammalian reproduction. I'll focus on the female mammals of greatest concern to most of us: girls and women.

Just because this chapter focuses on females doesn't mean that there's no relationship between eating and male mammalian reproduction. It's possible, for example, that eating too little or the wrong things might affect sperm counts. However, research on such subjects appears to be essentially nonexistent. In contrast, research on the relationships between eating and female mammalian reproduction abounds.

It's not surprising that researchers have concentrated on how food and female mammalian reproduction affect each other. The female mammal is the ultimate provider of food to the young both during pregnancy and immediately after birth. This early nutritive relationship is critical to the survival of the offspring. For an infant to survive, the infant's mother must obtain adequate food for herself until the infant is old enough to be weaned.

Thus survival of the woman results in survival of her offspring as well. This means that conception shouldn't occur unless there's a high probability that there will be sufficient food to sustain the woman and her offspring throughout pregnancy and lactation. And this means that women's bodies should have evolved such that their reproductive functions and their eating

-237-