Monkeys mistrust humans who are rude to fellow humans, according to a new study to find whether non-human primates base their evaluation of a person after witnessing third part interactions.

Tufted capuchin monkey
Tufted capuchin monkey

The study 'Third-party social evaluation of humans by monkeys' published in Nature Communications conducted various experiments to see whether monkeys judge a person depending on his behaviour with another person. Experiments between human beings were conducted in front of tufted capuchin monkeys (Cebus apella) to logically analyse this.

The first experiment entailed two actors performing in a 'helper' session in front of the monkey, where Actor A tried to get a toy out of a container and asked Actor B for help. The Actor B complied to help him. In this session, the monkey accepted food from both actors. In the non-helper session, Actor B refused to help Actor A. In this case, the monkey accepted more food from Actor A.

The researchers added another twist to their experiment where Actor B didn't even acknowledge Actor A's plea to help him get the toy out of the container because he was occupied in solving his own problem. Interestingly, the monkey accepted food from both actors as no one was at fault.

The other variation to the experiment was when Actor B explicitly refused to help Actor A. In this scenario, the monkey accepted little to no food from Actor B, the ruder human being of the two.

This study is on similar lines to the one done in 2010, where it was found that three-year-old babies are pro-social towards others based on their behaviours. The report Child Development published in Wiley found out that children avoid being social to people who cause, or intend to cause, harm to other people.

At AWI's Laboratory Animal Refinement and Enrichment Forum (LAREF) in 2003, four animal technicians said how important it is for veterinarians, practitioners and scientists alike to build trust with the animals they are conducting their tests. They concluded that humans cannot fool animals; they spontaneously pick up your intentions and feelings. It is only out of good gesture and dealings with third-party do they realise that they can trust humans. If not, they will be afraid and be ready to bit in self-defence.