Hrdy’s book cannot resolve questions concerning the mental health of children not cared for by their mothers, but it provides a relevant cross-cultural and evolutionary perspective on such care. First, the ethnological record shows that the nuclear family, although not rare, has not been common either, and it has always occurred within a broader social setting. Polygynous families (with two or more wives), polyandrous families (with two or more husbands), extended families under a single roof, mother-child households in a compound comprising several wives of a powerful man, and other arrangements have long shown that isolated nuclear households—mom, dad, kids—are not necessarily the human norm.
Likewise, the working mother has always been a central part of the human scene, and the classic stay-at-home mom of 1950s television may have been limited to Western cultures in that era. Women gathered, gardened, farmed, fished, built huts, made clothing and other necessities, even hunted in some cultures, in addition to caring for children and performing other domestic duties. Mothers often could not discharge these duties without help. Our species is not unique in caring for offspring cooperatively, but our great ape cousins don’t do it, and we take it to extraordinary levels.