We’re the only primates who really share

If we are social animals to our core, a position I’ve often supported here, social impulses — social cognitions — should be evident early in development, before socialization has had time to completely muddy the hard-wired waters.

A recent study comparing sharing in young children to sharing in chimpanzees supports the idea that the sharing impulse is far stronger in young children than it is in chimpanzees, and that some of the criteria for sharing are unique to us.

In “Collaboration encourages equal sharing in children but not in chimpanzees,” published online by Nature on July 20th, Katharina Hamman et al. performed a series of behavioural tests on three and four year old children.

The key distinction — and it’s a tricky one — is how much of children’s sharing behaviour is socially conditioned. As the authors note, children typically begin to share windfall resources sometime between five and seven years of age.

But if collaborative impulses are built into human nature, the authors argue, it should be possible to elicit sharing behaviours under certain conditions favourable to collaboration at an earlier age, before social sharing has been learned.

The authors posit that “the primordial situation for human sharing of resources is that which follows cooperative activities such as collaborative foraging, when several individuals must share the spoils of their joint efforts.” Three and four year old children in many cultures have been observed acting selfishly when presented with a “windfall resource,” but since we are the only great ape that forages in a truly collaborative way, they reason, by setting up conditions in which even very young children must act together to acquire a desired resource, it may be possible to test collaborative sharing in other than “windfall” circumstances.

Given that humans generate many or most of their resources collaboratively, a plausible hypothesis is that children would share a resource more equitably at an earlier age if it was not provided by adults as a windfall, but if instead they had to work together to produce it. Furthermore, we might expect this positive effect of collaboration on sharing to be confined to humans, among great apes, as only they have an evolutionary history of obligate collaborative foraging.

The authors created situations in which pairs of participants (two children or two chimpanzees) were presented with resource-sharing opportunities in circumstances where one member of the pair had control over more than half the resources and thus was in a position to act selfishly or unselfishly.

The key variable in different trial conditions was whether the unevenly-distributed resource had been acquired collaboratively or non-collaboratively (as a “windfall,” or as the result of individual work).

In a variety of tests with two and three year old children, collaboration (e.g., having to work together to remove a barrier) triggered sharing behaviours. Non-collaborative conditions produced selfish behaviours much more often. (If you’re interested in the details of the tests, and in how replications were varied to eliminate extraneous factors, that’s all in the source article.)

Under similar conditions, with the test apparatus adapted for their use, chimpanzees did not exhibit a greater tendency to sharing in collaborative versus non-collaborative conditions.

The trials support the authors’ hypothesis that humans share in situations where collaboration is necessary, and that chimpanzees don’t share because, unlike chimpanzees, we are true social sharers who were (and continue to be) collaborative foragers.

The authors conclude that” the ontogenetically first sense of distributive justice may be that participation in a collaborative effort demands an equal division of spoils.”

In a speculation typical of evolutionary psychology, but one that seems reasonable given the evidence in this study, the authors suggest:

A possible evolutionary picture is thus that this ‘social selection’ of a tendency to share the fruits of collaboration equally among participants became ever stronger as the need to work together jointly in subsistence activities became ever more obligate.

This conclusion rather blithely ignores the dramatic inequality of resources in our late capitalist society, but I guess I have to concede that that’s a slightly different topic — although I suspect that I see it as less different a topic than would many people.

More directly to the point, this study adds a few more twigs to the growing pile of evidence that we are irredeemably social creatures — not just in our behaviour, but in the cognitive wiring that produces our actions.


One thought on “We’re the only primates who really share

  1. The London rioters think so.. Doesn’t this belong with a lot of primary impulses we appear to be hardwired for, some of which fit with our present state and need to be cultivated and some of which need to be suppressed because of their harmful nature. Knowing we are social animals still leaves the devil in the details of how the socialization plays out.

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