This commentary on a Nature paper by Katharina Hamann and collaborators was first published in The Conversation on 21 July 2011.
One glance at our species can give the impression that we’re conniving, selfish and pretty greedy.
But look at other species and you’ll get a broader perspective: compared to other animals, people are superbly cooperative, and able to collaborate on a breathtaking scale. And we share a strong sense of how to fairly share the spoils.
As a parent I know that there are few more acute forms of embarrassment than when a young child refuses to share with another. By school age, children usually know how to share and do so freely – especially with close friends and family.
The rules that shape how we collaborate with one another and how we divide the spoils are critical to the functioning of human societies. But we still don’t know much about these rules, and how we acquire our knowledge of them.
New research out of Germany (and published electronically Nature.com) shows that even before they turn two, children have adopted sophisticated rules regarding sharing.
When one child is lucky enough to be given several toys, he or she only shares those toys around a quarter of the time.
If two children have to work together, but one child gets more toys than the other, the lucky child tends to share the spoils evenly three times out of four.
It seems that collaborative effort in winning the reward makes for an equitable division of the spoils, and even very young children know this.
It’s tempting to ask whether children all develop this knowledge innately or whether they acquire this knowledge from their environment. But attempts to polarise “nature” from “nurture” are almost inevitably doomed, and usually pointless.
The more interesting form of the question is how genetic and experiential factors guide the development of children’s knowledge about collaboration and sharing.
Interestingly, the Nature report’s lead author Katharina Hamann and her collaborators did a similar test on chimpanzees.
Chimps share occasionally, and they also collaborate, but they were no more likely to share the spoils of collaborative effort than of random lucky windfalls.
The researchers interpret the difference between their experiments on children and chimpanzees as evidence that humans’ inclination to share fairly comes from our tendency to collaborate to gather food.
For most of the last two million years, our ancestors were hunters and gatherers who worked in teams to find fruits, roots and seeds and to capture animals to eat. Among contemporary hunter-gatherers, folks who don’t collaborate or share well are either shunned as foraging partners or ridiculed.
Two weeks ago, Natalie Angier, writing in the New York Times, drew attention to this tendency in hunter-gatherer societies. She wrote that among the Hadza of northern Tanzania “people confronted by a stingy sharer do not simply accept what’s offered. They hold out their hand, encouraging the giver to keep giving until the giver finally draws the line.”
I must say, showing human children do something that chimpanzees do not doesn’t tell me much about the origin of a behaviour, and certainly it doesn’t tie that behaviour to our ancestral foraging mode.
But I’m willing to entertain the idea that even our youngest children have an instinctive tendency to share when they’ve worked together.
Now if only somebody could figure out how to encourage them to share their own toys, parents everywhere would be happier.