It has long been known that infants, long before they can talk, are sensitive to issues of fairness and some have probed to see if that is true for other animal species as well. A recent study looked at capuchin monkeys and dogs and found that they too seem to make what looks to us like moral judgments.

Their main conclusions are stated as:

• Capuchin monkeys negatively evaluate people who refuse to help a third party.
• Capuchin monkeys negatively evaluate people who exchange unfairly with others.
• Dogs negatively evaluate people who refuse to help their owners.
• Nonhuman species can engage in third-party based social evaluations.

The text of the paper of the paper says:

Our cautious interpretation of the overall pattern of results was that not only do capuchin monkeys show less willingness to take food from individuals who consistently explicitly reject another individual’s request for help, but that they take the intentionality behind failures to help into account. If refusals to help appear explicit, then that actor will be negatively evaluated; however, if failures to help appear inadvertent due to the potential helper already focusing on another task, then there is no negative evaluation of the non-helper.
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For example, dogs approached a person who won a tug-of-war game with another dog in preference to a person who lost the game (Rooney and Bradshaw, 2006). Dogs also more frequently approached a person whom they saw giving food to a “beggar” compared to a “mean” person who did not give food to the beggar (Kundey et al., 2010). When two people were equally generous towards a beggar, dogs showed a preference for the donor who received a positive response from the beggar (Freidin et al., 2013).
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Our studies with capuchin monkeys and dogs revealed no preference for helpful actors, but clear avoidance of non-helpful actors, and capuchins also avoided reciprocity violators.
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The studies reviewed here have shown that, like young human children, monkeys and pet dogs are not merely passive observers of other individuals’ interactions. Instead, in some circumstances at least, they pay attention to the outcome of the interaction, evaluate how the actors behave, and make use of that information in reaching a decision about which individuals to interact with or to avoid. Furthermore, in capuchin monkeys, it is not only the outcome that is monitored; the intentionality of an act (or of a failure to act) may be taken into account in the monkeys’ social evaluations of the actors; this aspect of social evaluation should also be investigated in dogs and other species.

You can read a popular article about it that appeared in the New Scientist here. The article quotes other researchers about this behavior.

Monkeys in the wild are likely to use similar processes to decide which members of their group they can cooperate with, says primatologist Frans de Waal of Emory University, Georgia, who has written about the origins of morality.

“Chances are that if these animals can detect cooperative tendencies in human actors, they also can in their fellow primates,” he says.

Dogs’ long relationship with humans means they’ve evolved to be extremely sensitive to our behaviour – not just to the dog, but also to other humans.

And our own sense of morality may even have its roots in these sorts of primitive evaluations of others.

“I think that in humans there may be this basic sensitivity towards antisocial behaviour in others. Then through growing up, inculturation and teaching, it develops into a full-blown sense of morality,” says Anderson.

The capacity to make evaluations of others could help to stabilise complex social systems by enabling individuals to exclude bad social partners, says Kiley Hamlin at the University of British Columbia, Canada. “This exclusion not only means that individuals who make social evaluations can themselves avoid harmful social interactions, but it also could serve to discourage individuals from behaving badly in the first place, as presumably they do not wish to be excluded from the social system,” she says.

De Waal sees a strong link between morality and reputation. “Human morality is very much based on reputation building, because why would you try to be good if no one cares?” he says. “I don’t think you can conclude that it makes the monkeys moral beings, but ‘image scoring’, as reputation building is sometimes called, provides an important key mechanism.”

Here is a video of the dog part of the experiment. What also caught my eye was that the first dog was a Blenheim Cavalier King Charles Spaniel, just like our very own Baxter the Wonder Dog. Baxter is so friendly towards everybody that I had not realized that he might be making moral discriminations.