Evolution of altruism: kin selection or affect hunger?

bridgecoverWalter Goldschmidt, Emeritus Professor of Anthropology from the University of California Los Angeles got in touch with us here at Neuroanthropology.net to give us a bit of a (friendly) hard time about unfortunate neologisms (touché) and to ask if we were familiar with his work. With my repeated posts on evolutionary psychology, he thought it might be of interest, especially his discussion of affect hunger.

What Prof. Goldschmidt did not realize is that I have an autographed copy of his book, Bridge to Humanity: How Affect Hunger Trumps the Selfish Gene (Oxford U Press listing, Amazon), and I’ve long thought it was both an excellent counter-argument to the ‘selfish gene’ hypothesis as well as a much more persuasive account of the possible evolutionary origins of altruism than the typical explanation: kin selection.

So, as a bit of a ‘thank you’ to Prof. Goldschmidt for providing such a compelling work, I’m going to post a bit of a book discussion here, focusing especially on Prof. Goldschmidt’s account of ‘affect hunger,’ which I find a much more neuroanthropologically plausible account of altruism than the usual account provided by evolutionary psychology discussions of ‘kin selection.’

Bridge Toward Humanity

From the book’s promotional material, we have this description:

In Bridge to Humanity, renowned scholar Walter Goldschmidt directs his attention to the way in which learning (that is, culture) has trounced genetic determinism as the force driving human behavior. In doing so, he reexamines what goes into being human, so the resulting book is an essay both on human origins and on human nature. Crucial to his thesis is the distinction between sexual love and nurturant love, which have separate evolutionary origins and make opposite psychological demands. Demonstrating that the desire for the affection of others is biologically based, Goldscmidt introduces the concept of affect hunger, the biological tool for nurturant love. Goldschmidt explains how affect hunger drives infants to obey directives from their parents in order to learn their language and rules. He further analyzes how affect hunger not only provides a reward system for learning language and other cultural institutions, but also remains a motive for social behavior throughout life.

Overall, the book is a passionately written, articulate discussion of human evolution and its implications for theory about human being. It’s a relatively slim, streamlined read, with less elaboration of supporting data, but far to many ideas for the space Goldschmidt has to explain between the two covers. He throws out numerous tangential thoughts that probably warrant their own more complete discussions; for these, you’ll have to look elsewhere.

For example, Goldschmidt provides a brief account of recent theoretical changes in anthropology, especially internal debates in the field, that have made it harder to talk about the biological consequences of human evolution. It’s so fast moving that even the least patient non-anthropological reader is likely to be able to sit through it, and the reader will be left with a much better sense of how current debates are shaped by old arguments.

Affect Hunger

Goldschmidt finds long-standing recognition among scientists that humans, like all mammals, have emotional as well as physical needs. He points out (2006:13), for example, that Abraham Maslow designated ‘love and affection and belongingness needs’ less important only than survival and physiological needs. With the importance of mutuality to human survival and well-being, Goldschmidt argues that the evolutionary pressures on humans are not just competitive: human infants need to convince their mothers to care about them. No wonder they’re so damn cute…

In one of the strongest chapters in The Bridge to Humanity, Goldschmidt lays out the diverse evidence that infants, especially, ‘hunger for’ affection, bodily contact, and emotion. For example, Prof. Jim McKenna’s research on co-sleeping suggests that bodily contact and the proximity of the mother affects sleep patterns in infants, perhaps even protecting them by helping them to regulate their own bodies (see Cosleeping and Biological Imperatives: Why Human Babies Do Not and Should Not Sleep Alone). Goldschmidt points to the neurological effects of mothers’ grooming on infant rats and Harlow’s classic studies of rhesus monkeys’ need for tactile stimulation. The monkeys deprived of contact in Harlow’s experiments ‘were dramatic evidence of the effect of affect starvation’ (ibid.:48).

Because they need this contact, human infants have ‘sociophilic traits,’ according to Goldschmidt, behavioural traits that seem to have no other purpose but to encourage, facilitate and reward social interaction, almost as an end in itself. Smiling, nuzzling, laughter, imitation, our facial structure — many of our distinctive traits can be traced to these neonatal ploys to get and keep a mother’s attention.

One thing that makes Goldschmidt’s account unusual is that he focuses, not on the pair bond of human mating as a motivation for affective change, but on the mother-child bond of nurturing. He writes: ‘Nuturant love is a more recent animal attribute [than competition], coming with the live births that are the hallmark of the mammal class of animals’ (ibid.:35). Although I have problems with the computer metaphor (as long-time readers know), he argues that this need for nurturing is crucial to shaping human psychology:

Both child and mother are programmed to seek and give expressions of affection; this is the the biological ontogeny of affect hunger. Evolutionarily, it began as a device to assure the care and feeding of the neonate among social mammals and is built upon to motivate the neonate to learn from adults and thus to conform to the expectations of the troop, pride, or band and, finally, for human infants to undergo the lengthy curriculum necessary to become a human adult. This hunger for affection is essentially insatiable; it continues as a wish for acceptance, approval, and influence in the ever-expanding community in which every child is to live. (ibid.:37)

Goldschmidt points out that many of the physical manifestations of romantic or erotic love (and addiction) are actually quite similar to those involved in nurturing (ibid.: 54-57). This parallel processing might be interpreted as an exaptation: the neural-affective processes that were selected over evolutionary time because they raised the likelihood of an infant’s survival might subsequently become entangled in other social interactions and behaviour. Selected for ‘affect hunger’ by our helplessness as infants, we went on to seek to fill this hunger in a wide range of ways, not all of them terribly adaptive.

This focus on mother-child bonds as the root of human sociality, away from social relations among adults, is, in my opinion, one of the more interesting, plausible, and far-reaching suggestions that the book offers. So often, arguments for the evolutionary value of social traits (like altruism) are premised upon mating scenarios, which seem much less plausible because pair bonding between mothers and fathers is much less pressing than the mother-child bond. Any argument that pair bonding in humans is ‘universal,’ for example, must contend with the painfully obvious evidence that humans are not always so good at pair bonding and fathers do not inevitably stick around to help raise children. If pair-bonding is the evolutionary reason for humans’ pro-social traits, than its surprising that we’re so lousy at pair bonding, even though we’re quite adept at social life.

The book goes on to discuss the implications of this theory for a range of subjects including cultural variation in child rearing, learning processes, ritual, cultural evolution, ‘the soul,’ differences between foragers and farmers. I have some issues with the latter parts of the book that I might get a chance to comment upon (especially some of the thinking about cultural evolution and adaptation, and that stuff on the soul), but I want to focus on this discussion of affect hunger and its impact on an evolutionary account of the rise of altruism and other social traits.

Affect Hunger or Kin Selection?

Most often, evolutionary psychologists explain the presence of social behaviour like altruism in humans and other animals by reference to kin selection. For those of you who aren’t necessarily familiar with this literature, kin selection is the idea that natural selective pressures can favour a gene if it provides a trait that makes one’s relatives more likely to survive because that relative likely carries many of the same genes. As David C. Queller and Joan E. Strassmann write: ‘Selection normally favors a gene if it increases reproduction, because the offspring share copies of that gene, but a gene can also be favored if it aids other relatives, who also share copies. It is this selection via relatives that is referred to as kin selection’ (2002: R832).

At its foundation, these approaches to altruism really assume that there is a ‘selfish’ selective calculus to seemingly selfless acts, a genetic advantage to being altruistic, if only because it makes our genes likely to live on in those we save even if their copies in our own body go down the gurgler in the brave act of saving somebody else’s copies of those genes. I have no problem with arguing people are selfish, only with arguing that altruism is a good way to be selfish.

Ultimately, I tend to find arguments for kin selection unconvincing for a whole host of reasons, among them:

1) There’s seldom any consideration of the neural mechanisms that might be responsible, only the assumption that the ‘gene’ will cause altruistic behaviour if it is favourable to the gene’s transmission.

2) An inability to explain why, if natural selection cares about our close relatives so much, our ‘altruism gene’ couldn’t be much more selective about who we feel altruistic about, say, a ‘mafia family altruism’ where people don’t feel any altruism toward those to whom we’re not related. (I know some theories of kin selection try to account for our indiscriminate altruism by assuming that our ancestors were generally in the presence of only related individuals, but this certainly wouldn’t explain the way human altruism even extends to other species.)

3) The kin selection perspective tends to take an adaptationist view of natural selection, assuming that organic variation can easily produce candidate ‘adaptations’ to suit any environment and that all traits of an organism are necessarily adaptive (when, in fact, it’s a whole organism that is selected, not each individual trait, and traits are often connected genetically so that selection might be acting on another trait produced by the same gene).

4) The problem of how closely related we need to be to kin for our altruism to really be a selective advantage if we are in competition with each other is daunting. Haldane (1955) famously suggested that, following strictly on the mathematics of ‘comparative advantage’ and selfish promotion of our own genes in someone else’s body, we should be more careful about our altruism, laying down our own life only if we could save two brothers or eight cousins because of the shrinking likelihood that our relatives carry our genes the more distant the relation. That’s a hell of a lot of people to be saving at once, so a rational, ‘selfish’ gene would likely exhibit altruism only rarely, when the risk was offset by danger to a large number of relatives.

In many ways, Goldschmidt’s account of affect hunger in the infant, and the many sociophilic traits that infants have in order to attract the attention and affection of helpful adults, makes a lot more neuroanthropological sense. Rather than a calculation of advantage, we have a developmental trait that’s well documented in infants and a plausible account of how it would carry through in adult traits.

The kin selection account explains a widespread trait of humans by reference to an event that might not have been too common; the sacrifice of one life for a number of related individuals. In contrast, affect hunger is a universal trait structured to seek satisfaction for a universal survival need among helpless infants for a bit of assistance, nurturing, and parental care.

Although some neo-Darwinists might only want to see the role of natural selection in evolution, Walter Goldschmidt’s account of affect hunger is consistent with a broader evolutionary model that considers, not only the driving pressures of selection, but also the material and developmental needs of each individual organism. That is, survival may demand not just a willingness to compete, but also a lot of tricks to wheedle the resources we need out of those around us, even when we’re just a cute, toothless, slobbering little monkey. That’s why, even before we can do most anything except eat and poop, we’re already really good at manipulating each other.


Goldschmidt, Walter. 2006. The Bridge to Humanity: How Affect Hunger Trumps the Selfish Gene. Oxford U Press; New York.

Haldane, J. B. S. 1955. ‘Population Genetics.’ New Biology 18: 34–51.

Queller, David C., and Joan E. Strassman. 2002. ‘Quick Guide: Kin Selection.’ Current Biology 12:R832. (download pdf)

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Trained as a cultural anthropologist at the University of Chicago, I have gone on to do fieldwork in Brazil and the United States. I have written one book, Learning Capoeira: Lessons in Cunning from an Afro-Brazilian Art (Oxford, 2005). I have also co-authored and co-edited several, including, with Dr. Daniel Lende, The Encultured Brain: An Introduction to Neuroanthropology (MIT, 2012), and with Dr. Melissa Fisher, Frontiers of Capital: Ethnographic Reflections on the New Economy (Duke, 2006). My research interests include neuroanthropology, psychological anthropology, sport, dance, human rights, neuroscience, phenomenology, economic anthropology, and just about anything else that catches my attention.

8 thoughts on “Evolution of altruism: kin selection or affect hunger?

  1. Not so fast with the rejection of kin selection! Kin selection doesn’t require you to sacrifice your life for relatives. Just for you to sacrifice something for relatives.

    Evolution would predict that people would be extremely unlikely to sacrifice their lives for non-close relatives. I think that the statistics probably bear this out.

    Kin selection is not the only evolutionary cause of altruism – co-operative breeders would also display altruism (https://mywebspace.wisc.edu/kacronin/web/Snowdon%20&%20Cronin%202007.pdf)

    Also, there’s a difference between co-operative and altruistic. I suspect that Mafia brotherhoods are more of the latter than the former.

    Religions commonly trigger motifs of family (http://www.sciencedaily.com/releases/2008/09/080909122749.htm). Non-genetic altruism may be an example of cultural evolution, facilitated by religion.

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