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.
Hrdy on the experience of infants among the!Kung:
From their position on the mother’s hip they have available to them her entire social world…. When the mother is standing, the infant’s face is just at the eye-level of desperately maternal 10- to 12-year-old girls who frequently approach and initiate brief, intense, face-to-face interactions, including mutual smiling and vocalization. When not in the sling they are passed from hand to hand around a fire for similar interactions with one adult or child after another. They are kissed on their faces, bellies, genitals, sung to, bounced, entertained, encouraged, even addressed at length in conversational tones long before they can understand words.Hrdy is much taken with an explanation of human evolution that focuses on cooperative child raising, and I think that is overblown. Humans do everything cooperatively, from baby care to war. Our cooperation is facilitated by our greatest invention, language, and made possible all of our achievements. I don't see why we should focus on any one type of cooperation as the evolutionary driver. Humans are also, as Konner hints in his list of family types, remarkably flexible, able to do even fundamental things like marriage and infant care in a thousand different ways. It is almost always a mistake to hold up one model of family life as the inescapable norm, because somewhere some human group has done it differently and gotten by quite well. The one thing that defines our experience across all human societies is our cooperative nature. Through language we connect to those around us, through culture and memory and writing we connect to others far away and long dead. The accumulation of shared knowledge made it possible for hunter-gatherers to survive in deserts, jungles and tundra, and it has now carried us to the moon. What is uniquely human resides, not in any individual, but in all of us together.