Humans appear to be pre-programmed with a sense of justice. This is perplexing from an evolutionary standpoint since you'd think we'd be predisposed to seek advantage for ourselves and our families wherever we could. Fairness, on the other hand, is critical for humans to be able to aid one another. Human cooperation is built on reciprocal altruism, which means that we help others because they have previously helped us or may do so in the future.
This type of collaboration is only possible when people can keep track of each other's efforts and rewards - something that a sense of fairness can help with. But what about animals that aren't human? Is fairness a trait that distinguishes humans from other animals, or has it evolved in non-human creatures as well?
An "inequity aversion task" can be used to test for this in animals. One test subject is rewarded for completing a task, while the other is given a "booby prize," which is something they don't enjoy. Individual animals with a strong sense of fairness, you'd think, would either stop participating in the experiment or refuse the treat.
Brown capuchin monkeys were one of the first species to be examined for inequity aversion. One person was given a slice of cucumber in exchange for a token in a task where the monkeys had to trade a token for a treat, whereas a model individual – another monkey not involved in the experiment – in an adjacent cage was given a grape for the same activity. Capuchin monkeys prefer grapes to cucumbers, and those who were given the latter began to "protest" by throwing the unappreciated vegetable back at the experimenter.
The capuchin monkeys were also acutely aware of the inequity in the amount of work required to obtain a reward. They stopped participating when they had to "earn" a reward and saw that their experimental partner received it as a "gift." Other monkey species, such as chimps, rhesus macaques, and long-tailed macaques, have been demonstrated to exhibit inequity-related behavior. Aside from primates, dogs and rats are two more highly sociable mammalian species that have been demonstrated to be sensitive to unfairness.
But what about creatures that aren't mammals? In recent years, the corvid family has emerged as one of the most important models for researching bird cognition. Corvids, which include ravens, crows, magpies, and jays, are a huge family with over 120 species. Corvids are highly sociable and have social structures that are adaptable. For example, adult ravens live in territorial pairs, whereas jackdaws reside in big community groups. The sociability of some species, such as the carrion crow, is dependent on the habitat; in some settings, they may breed in male-female pairs, while in others, they may breed in cooperative groups.
Different corvid species exhibit various sorts of spontaneously occurring cooperation. They assist one another in aggressive interactions and exchange resources such as food and predator information. We expected corvids to have a sense of justice and unfairness, considering the extent to which they have been seen cooperating in the field.
We chose to put them through the same ordeal as the primates. Four common ravens and six carrion crows were used as test subjects. The birds were rewarded with a piece of cheese (which they enjoy) and a bit of grape as a booby prize. In one trial, both birds received the same food reward for trading a token with a human experimenter, whereas in another, one bird received only grapes while the other received cheese for exchanging.
We also attempted an "effort control" experiment, in which one of the test subjects had to exchange its token for either a piece of cheese or a piece of grape, while the other bird received the identical reward as a gift and did not have to swap for it.
The subject crow – the bird who was being treated unfairly – ceased accepting the reduced reward under the "inequity" condition. They stopped trading their token for the reward under "effort control" when they witnessed the other bird collecting its prize with no effort. They saw how they were being handled unfairly in both cases and chose not to comply.
Corvids are similar to some mammals in this regard and the evolution of this understanding of what is fair and what isn't may have been aided by the tremendous complexity and flexibility of cooperative behavior. The fact that inequity aversion is found in a variety of ape species, as well as corvids, suggests that cooperative animals share a sense of fairness and collaboration, which has allowed them to evolve sociability.
About the Writers:
Maina Zaina, Writer and a Virtual Assistant at AVCreativity Studio. She enjoys media entertainment and is an avid fan of "K-Wave". She loves her job because she is exposed to different types of entertainment. She also believes in the saying "If you want to be successful, don't seek success - seek competence, empowerment; do nothing short of the best that you can do" by Jaggi Vasudev
Pamela Elizabeth, Editor-in-Chief at AVCreativity Studio. Earned a Bachelor’s Degree of Secondary Education Major in English. She loves going on little adventures alongside reading good books. She is enthusiastic about her work and ensures that her clients receive the finest service possible.