The Breast and Lactation

Abstract

The breast or mammary gland provides milk for the nourishment of the newborn mammal. This system of postnatal nutrition is considered to be of such evolutionary importance as to justify its taxonomic use for an entire class of animals. The structural and behavioural complexity of the mammal requires a considerable degree of postnatal development and growth, and the phenomenon of suckling enables the mother to provide extrauterine nutrition while the young are maturing sufficiently to feed themselves. This places a great burden on the mother who devotes much energy to the nurture of her young. One obvious consequence is that reproductive rates of mammals are low in comparison to other types, but the success rate is higher because parental care and feeding of the young are so well developed.