September 20, 2011

The biological basis for justice and altruism-part 2

(An expanded version of a talk given at CWRU's Share the Vision program, Severance Hall, Friday, August 26, 2011 1:00 pm. This program is to welcome all incoming first year students. My comments centered on the ideas in the common reading book selection Justice: What's the right thing to do? by Michael Sandel. See part 1 here.)

The primatologist Frans de Waal in his excellent book The Age of Empathy (2009) provides case study after case study of animals displaying a keen sense of justice and fairness, providing convincing evidence that these impulses are innate in us and arise from our common evolutionary history with other animals. In a newspaper article titled Morals Without God? he writes about his observations:

Chimpanzees and bonobos will voluntarily open a door to offer a companion access to food, even if they lose part of it in the process. And capuchin monkeys are prepared to seek rewards for others, such as when we place two of them side by side, while one of them barters with us with differently colored tokens. One token is "selfish," and the other "prosocial." If the bartering monkey selects the selfish token, it receives a small piece of apple for returning it, but its partner gets nothing. The prosocial token, on the other hand, rewards both monkeys. Most monkeys develop an overwhelming preference for the prosocial token, which preference is not due to fear of repercussions, because dominant monkeys (who have least to fear) are the most generous.

It is not only humans who are capable of genuine altruism; other animals are, too. I see it every day. An old female, Peony, spends her days outdoors with other chimpanzees at the Yerkes Primate Center's Field Station. On bad days, when her arthritis is flaring up, she has trouble walking and climbing, but other females help her out. For example, Peony is huffing and puffing to get up into the climbing frame in which several apes have gathered for a grooming session. An unrelated younger female moves behind her, placing both hands on her ample behind and pushes her up with quite a bit of effort, until Peony has joined the rest.

We have also seen Peony getting up and slowly move towards the water spigot, which is at quite a distance. Younger females sometimes run ahead of her, take in some water, then return to Peony and give it to her. At first, we had no idea what was going on, since all we saw was one female placing her mouth close to Peony's, but after a while the pattern became clear: Peony would open her mouth wide, and the younger female would spit a jet of water into it.

Such observations fit the emerging field of animal empathy, which deals not only with primates, but also with canines, elephants, even rodents. A typical example is how chimpanzees console distressed parties, hugging and kissing them, which behavior is so predictable that scientists have analyzed thousands of cases. Mammals are sensitive to each other's emotions, and react to others in need.

A few years ago Sarah Brosnan and I demonstrated that primates will happily perform a task for cucumber slices until they see others getting grapes, which taste so much better. The cucumber-eaters become agitated, throw down their measly veggies and go on strike. A perfectly fine food has become unpalatable as a result of seeing a companion with something better.

We called it inequity aversion, a topic since investigated in other animals, including dogs. A dog will repeatedly perform a trick without rewards, but refuse as soon as another dog gets pieces of sausage for the same trick. Recently, Sarah reported an unexpected twist to the inequity issue, however. While testing pairs of chimps, she found that also the one who gets the better deal occasionally refuses. It is as if they are satisfied only if both get the same. We seem to be getting close to a sense of fairness.

Can we assume that the human species has also inherited this biological predisposition to justice? Yes, because we are all linked by the great tree of life to all other species. If we go back far enough in our lineages, we will find a common ancestor for all of use, which makes us all effectively cousins, and so you can treat this occasion, where all of us have gathered together in this magnificent concert hall, as a family reunion where you are meeting long-lost relatives. In fact, if you and your pet dog or cat trace your lineages back about a hundred million years, you will find that you have a common ancestor, which is a nice thing to realize.

So given that the desire for justice is so widespread among so many different species, it is very likely that we have inherited the desire for justice from deep evolutionary times. In his book, de Waal concludes that studies in the fields of anthropology, psychology, biology, and neuroscience reveal that we are essentially group animals: "highly cooperative, sensitive to injustice, sometimes warmongering, but mostly peace-loving. A society that ignores these tendencies cannot be optimal." (p. 5)

But is there any direct evidence that humans have a biological predisposition that makes them favor justice and fairness? Yes there is, and I will explore that in the next (and last) post of this series.


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I have noticed the necessity of fairness and justice between the animals in my own home. They tend to always seek this from each other.

Posted by Sophie on September 24, 2011 01:11 PM