I just finished watching an episode of PBS's Nova about animal intelligence. Unfortunately, the episode is not available to stream for free but here is a transcript. I can't see how someone would watch/read this and argue animals do not have a prolepsis of justice/fairness. And if a Prolepsis of that, what else? And I feel (it brings me pleasure) that I'm justified in making this observation since Epicurus himself looked to animals and infants to formulate parts of his Philosophy.
Transcript selection (emphasis added):
NARRATOR: Frans believes that primates, as they negotiate their social lives, are very aware of the competition. And so he's come up with another experiment, this one to test their sense of justice.
Do they realize if they're being treated fairly or not, compared to others?
FRANS DE WAAL: Normally, you would think the only thing an animal should care about is, “What do I get for my task? I work, I get rewards,” but, no, they're comparing with what the other one is getting.
NARRATOR: Frans begins the fairness test with the capuchin monkey. These small, clever animals are kept in large enclosures, but for the short duration of the test, they're in a lab area. Each monkey carries out a simple task: they have to give a small stone to the experimenter, in exchange for a reward.
When both get a reward of cucumber, everyone's happy. But watch what happens when the one on the right receives a grape reward, instead.
FRANS DE WAAL: If you start giving one of them grapes, which are far better than cucumber, then the one who gets cucumber becomes very upset and becomes agitated, emotionally agitated.
NARRATOR: It turns out, quite a few creatures, including ravens and dogs, will protest if they get the short end of the stick, as if they know that they're being treated unfairly. But what about a concern for injustice for the other guy?
Research with one of our closest relatives, a highly social chimp, called a bonobo, is revealing some surprises.
At the Lola ya Bonobo orphanage in the Congo, animals spend most of their days in the forest, but come inside for short periods of time for experiments like this.
One bonobo is inside an enclosure. The door is locked and can only be opened from the other side. Here, another bonobo, a stranger, is given a delicious pile of fruit.
So, what will she do?
BRIAN HARE: We recently discovered that bonobos can share with strangers, that they actually will sacrifice their own food for the opportunity to interact with another bonobo they've never met before. That's not something that we thought another species would do. When we think about nature as “red in tooth and claw,” that you would share with somebody you don't share any genes with, it's not in your family, they're not even in your group, I thought that was something that humans did. So the fact that a bonobo does that is remarkable.
It's the closest you can think of to doing charity in animals.