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Clues to the origins of social justice found in six year olds and chimps

Cooperation is one of the pillar of successful communal living, with the convention that those who break the social norms are punished. Researchers have traced evolutionary evidence for this urge for justice in six-year-old children and chimpanzees, with both showing an interest in being present when justice is meted out.


Scientific advances

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Past research has studied empathy amongst humans and animals, demonstrating how humans and some animal species display distress when witnessing others subjected to harm. These empathetic behaviours are said to safeguard social norms, while facilitating cooperation.

New research has indicated that alongside empathy, cohesive communities also rely on a sense of justice. The study evidenced chimpanzees and six-year-old children not only going out of their way to see punishment enacted on perceived wrongdoers, but seeming to enjoy the experience.

When justice must be seen to be done

The researchers, drawing on work developed under the EU-funded DEVBRAINTRAIN and SOMICS projects, wanted to know more about the origins and development of this judgmental behaviour. Writing in the journal Nature they outline how they wanted to ascertain at what age this impulse to witness punishment for perceived antisocial behaviour starts and whether it is also present in chimpanzees, our closest relatives.

In the case of children, the scientists set up a scenario with a puppet theatre using three characters. One character was kind to the children by letting them have their favourite toy, one was unsympathetic by withholding the toy, and a third pretended to hit the others with a stick. The children in the audience were aged four to six and had a choice to either pay with a coin to watch the stick hitting or use the coin to buy a sticker.

The researchers found that children chose the stickers when the ‘good’ puppet was being hit, but a significant number of the six year olds forwent the stickers and paid to see punishment meted out against the ‘bad’ puppet. The researchers even reported that the six-year-olds demonstrated pleasure at the sight, as evidenced by their facial expressions, in contrast to the four- and five-year-olds.

To look at chimpanzees, researchers set up a scenario at Leipzig Zoo whereby two zookeepers enacted cooperative and uncooperative roles, with one feeding the chimps, while the other denied food and again a third character dishing out a beating with a stick. The researchers observed that a significant number of the animals made the effort to witness the uncooperative keeper being beaten, even when it entailed opening a heavy door to get a view. On the other hand, the chimps avoided witnessing the pretend beating to the cooperative keeper and even remonstrated when it was inflicted.

A precondition for successful community living

Given the close evolutionary link between chimps and humans, it is hypothesised that the desire to see what is perceived to be just punishment delivered against wrong-doers, developed in evolution as a social strategy to maintain cooperation and cohesion, keeping communities safe.

The findings also support previous research indicating the importance of the age of six in a child’s cognitive, emotional and social development, with children starting to display an interest in fairness and associated traits such as sacrifice in the interests of others.

The contributory DEVBRAINTRAIN (Neurocognitive mechanisms of inhibitory control training and transfer effects in children) project is looking at the development of the ability to control behavioural impulses, crucial for cognitive development and for later life wellbeing. The team is particularly interested in how the brain’s plasticity could enable improved inhibitory control, especially in childhood.

The work also benefited from input from the SOMICS (Constructing Social Minds: Coordination, Communication, and Cultural Transmission) project. Researchers here are working to better understand how shared perceptions, action and communication combines with general knowledge to create common social ground. They are comparing data from infants, children, adults and primates, in addition to drawing on anthropological evidence.

For more information, please see:
DEVBRAINTRAIN project website
SOMICS project website


Hungary, United Kingdom