Our unique sociability among the apes arises from our gift for mutual understanding, or intersubjectivity. Hrdy argues that we are ‘wired’ to cooperate. She grounds her analysis of how this came to be in evolutionary psychology and sociobiology; Charles Darwin’s theory of evolution by natural selection was her guiding principle. Her main evidence comes from forager societies, primates, and, sometimes, other animals.

Since Darwin, there have been three main attempts to apply his theory to human societies. The first, framed in terms of eugenics, reached its high watermark between the 1910s and 1930s, and collapsed in the wake of Nazi Germany’s ‘Final Solution’. Sociobiology originated in the 1970s – at the same time as second-wave feminism – and aroused immense controversy within the academy during the 1980s, not least for the attempts of some proponents to demonstrate ‘the inevitability of patriarchy’.

During the 1990s sociobiology morphed into evolutionary psychology, whereupon some proponents generated controversy by making a case for the evolutionary foundations of rape. More generally, evolutionary psychology emphasised the biological drivers of human behaviour, mediated through selected psychological mechanisms. Eventually it expected to overturn the existing superstructure of the social and behavioural sciences, or what it called the ‘Standard Social Science Model’. Not surprisingly, evolutionary psychology was not a hit among feminists, or most social scientists. Yet evolutionary psychology has gone from strength to strength, in the United States especially. It draws its support from psychologists, anthropologists, and biologists, and has institutionalised its paradigm through academic programs, specialist journals, and textbooks. It has also successfully promoted its cause to a popular audience, through bestsellers (such as Jared Diamond’s The Third Chimpanzee: The Evolution and Future of the Human Animal [1992] and Steven Pinker’s The Blank Slate: The Modern Denial of Human Nature [2002]) and adroit use of the media.

Hrdy is an anthropologist, immersed in the sociobiology and evolutionary psychology paradigms from their beginnings. Yet she is not your common evolutionary psychologist. She is an independent thinker who is willing and able to take on key platforms in the evolutionary psychology orthodoxy. In Mothers and Others, she challenges the orthodoxy in two main ways.

First, Hrdy argues that evolutionary psychology routinely overemphasises our aggression and ‘killer instincts’ at the expense of our sociability. She argues that this bias arises partly because the common chimpanzees (Pan troglodytes) have been studied intensively for much longer than bonobos (Pan paniscus). Chimpanzees are dominance-oriented and aggressive, sometimes murderously so. Bonobos are playful and tolerant. Hrdy observes that because chimpanzees conform more closely to ‘widely accepted stereotypes about human nature’, there is a bias towards viewing them as the template for the genus, while dismissing bonobos as ‘some eccentric offshoot’. Yet bonobos, she argues, make a better template for understanding human sociability and mutual understanding.

Second, Hrdy argues that evolutionary psychology devotes too much attention to mothers at the expense of others. The others include fathers and those whom she describes as alloparents – older siblings, grandmothers, aunts, uncles and so on. Again, Hrdy argues that the bias arises from skewed evidence. The !Kung of the Kalahari are among the most studied of forager societies, but their infants spend a mere twenty-five per cent of their time with alloparents – a lot more than other apes, but much less than other forager societies. The Efe of Central America – whose infants average fourteen different caretakers in their first days of life – are atypical at the other end of the scale, but they are much less studied. Most forager societies deploy fewer alloparents than the Efe, but more than the !Kung.

Hrdy argues that shared care is the foundation of our sociability and mutual understanding. It is pervasive among forager societies, and common among primates and other animals, notwithstanding exclusive maternal care with other apes. Shared care enabled humans to breed faster than other apes, and infants to survive in ‘worlds where more than half of older siblings born would starve, be murdered or eaten, or succumb to accident or disease before they matured’. It was essential for child survival – the evolutionary equivalent of a diversified portfolio in uncertain markets.

At the end of Mothers and Others, Hrdy reflects upon the modern lament of loneliness and the loss of community. From her perspective, the trouble began much further back, with the transition from forager to agricultural societies. Agriculture fundamentally changed the ways in which children were raised, as people settled in one place, built walled houses, and grew and stored food. It also changed the ways in which humans organised their communities: predation and warfare became more widespread, and male kinship groups became more important for security. In this context, patriarchal ideologies and institutions flourished, and child survival became increasingly decoupled from the need to be surrounded by responsive, protective caretakers.

In contemporary times, the decoupling of child survival and shared care is virtually complete. The best quality day-care centres successfully simulate the nurture provided to infants in forager societies, but most arrangements – whether isolated maternal care in the suburbs or inadequately staffed day-care centres – do not. ‘And perhaps for the first time in human history,’ Hrdy writes, ‘exceedingly high rates of child survival coincide with sobering statistics about the emotional well-being of children.’ In particular, she notes increasing evidence of ‘disorganized attachment’ among children across socio-economic groups, ‘paralyzed by their own contradictory emotions of fear and need’. In the longer term, Hrdy worries that, as an ever-increasing proportion of humans survive and reproduce irrespective of care, there is no selection mechanism for sociability and mutual understanding. In turn, these qualities will fade from the species ‘as surely as sight in cave-dwelling fish’.

Mothers and Others is an engaging book. It is full of fascinating information from diverse fields, imaginatively harnessed to produce a coherent account of our genetic predispositions as a species. Above all, it challenges the pervasively sexist tradition within evolutionary psychology, which routinely highlights aggression and maternal care at the expense of sociability and shared care. In doing so, the book provides a rich foundation for engagement with the social sciences, exploring the articulation between our genetic pre-dispositions and contemporary human societies. Yet I suspect that Hrdy would reject this recommendation. Her points of reference are those of sociobiology and evolutionary psychology alone. In turn, she resolutely refuses to acknowledge their ideological dimensions, the ambiguity of their scientific credentials, and the immense scope for post hoc interpretation of evidence. In particular, Hrdy sidesteps their pervasive sexism. She goes to great lengths to show how skewed evidence explains their bias towards aggression and maternal care at the expense of sociability and shared care. She gives no consideration to the influence of patriarchal ideology within sociobiology and evolutionary psychology, and the challenge of second-wave feminism.

Hrdy dismisses the social and behavioural sciences, and ignores feminism altogether. For example, her only direct reference to sociology throughout the book is a disparaging reference to ‘sociologists of the family’ who reify the nuclear family as optimal for children without reference to historical, economic, or social conditions. The sociologists to whom she refers are a tiny band of moral conservatives in the United States, no more representative of sociology than chimpanzees of primates, or the !Kung of forager societies. In fact, most contemporary sociology of the family is heavily informed by second-wave feminism, and emphasises the flexibility, contingency, and diversity of family forms, consistent with Hrdy’s analysis.

More generally, there is a deep tension throughout Mothers and Others around agricultural and industrial societies, past and present. For the most part, Hrdy ignores them, for the simple reason that, by the time these societies arose, our genetic make-up had largely taken shape. From this perspective, the institutions of agricultural and industrial societies are largely understood as expressions of our underlying genetic make-up; for example, the way mothers ‘decorate, arrange, and train their babies in ways that make them more flamboyantly attractive to other caregivers’, akin to the flamboyant natal coats of infant-sharing primates. Alternatively, social institutions are understood as violations of our underlying genetic make-up; not least the nuclear family separated from extended kin support, and budget day-care.

The distinction between institutions that ‘express’ our underlying biology and those that ‘violate’ it begs the question as to how we distinguish one from the other. Hrdy’s challenge to mainstream evolutionary psychology regarding male aggression and exclusive maternal care shows that this is not a straightforward exercise. There is plenty of room here for interpretation and ideology.

In any case, Hrdy acknowledges the near-absence of ‘fixed behaviour patterns’ among humans, compared with other mammals. The innate flexibility of our brains makes Hrdy’s routine deployment of animal evidence deeply problematic. More generally, it makes humans especially responsive to Lamarckian systems of knowledge acquisition and transfer, or culture. By implication, it creates the scope for an extraordinary array of social institutions, which do not so much ‘express’ or ‘violate’ our underlying biology as express our underlying plasticity.

Hrdy herself describes how patriarchal ideologies and institutions can assume their own dynamic. For example, ‘a fixation with chastity can take on a symbolic and institutional life of its own’, to the point where it trumps child welfare and survival. Specifically, the South Asian custom of suttee (or widow burning) ‘deprived dependent children of grandmothers and great-aunts, as well as mothers’. The fact that institutions can take a life of their own demands a level of analysis beyond sociobiology and evolutionary psychology.

Ultimately, Hrdy violates her own paradigm in making the case that sociability and mutual understanding are at risk of fading from the species. The claim flies in the face of her premise that our genetic make-up was forged over deep time; hence, the reliance upon evidence from animal studies and forager societies, and the lack of interest in agricultural and industrial societies. In this instance, Hrdy confuses the innate plasticity of our brains and genetic evolutionary selection. In fact, it is the plasticity of our brains and the creativity of our social institutions that give us the capacity to address the challenges faced by contemporary societies.

Think of it like this: Hrdy currently travels on planes where her fellow passengers are exclusively sociobiologists and evolutionary psychologists. The patriarchs of these fields sit in first class. Hrdy has no doubt that she travels in the best company. She is also keen to upgrade to first class, and takes care not to offend her fellow passengers. But perhaps Hrdy should consider travelling with other passengers more often, not least feminists and social scientists. She would not lose any appendages, and her analysis of contemporary societies would benefit. For their part, feminists and social scientists would also benefit from a more sophisticated analysis of our biological predispositions. There is scope here not just for mutual understanding, but for better science.