I have had the pleasure of
meeting Franz de Waal on two occasions.
The first time was during an NSF Summer Institute at Dartmouth and the
second was when he graciously agreed to sit on a panel I organized. He is a very nice fellow.
Since 2003, de Waal and Dr.
Sarah Brosnan have been studying fairness behavior in monkeys. Their basic research questions, as I
understand it, is to what extent do nonhuman primates recognize and respond to
situations of fairness and unfairness and how can this be explained by
evolutionary theory? The pair have published
a paper surveying the literature and their findings in Science. I don’t have access
to the paper yet, but I have just read a
summary of it at phys.org. Here is
Brosnan’s description of their hypothesis:
"This sense
of fairness is the basis of lots of things in human society, from wage
discrimination to international politics," Brosnan said. "What we're
interested in is why humans aren't happy with what we have, even if it's good
enough, if someone else has more. What we hypothesize is that this matters
because evolution is relative. If you are cooperating with someone who takes
more of the benefits accrued, they will do better than you, at your expense.
Therefore, we began to explore whether responses to inequity were common in
other cooperative species."
Obviously, the question of the
evolution of a sense of fairness in monkeys and nonhuman apes bears of the
question of the natural history of human fairness. Human beings are extraordinarily cooperative
animals. Our capacity for cooperation is
possible in large part because we are capable of a sense of obligation toward
others and a tendency toward righteous indignation when others fail to oblige
in return.
It is not immediately obvious
how either capacity emerges in our evolutionary history. The sense of obligation means that we give
unto others when we don’t have to do so, which entails a cost in
resources. If I share what I have in my
hands, I have less for myself. The
indignation means that I may refuse to accept a share from another that I
regard as unfair, thus getting nothing (and perhaps getting into a fight)
rather than getting something. In a
situation where resources and needs are marginally related (which was our
situation for most of our time as a species on this earth) getting something rather
than nothing would seem like the obviously better choice.
It turns out that the
indignation part of the equation is easier to explain. Here is a summary of their 2003 paper in Nature.
In this study, brown capuchin monkeys became agitated and
refused to perform a task when a partner received a superior reward for that
same task. To view video footage of the study, visit http://www.youtube.com/watch?v=meiU6TxysCg.
Since then, Brosnan has tested responses to inequity in nine different species
of primates, including humans. She has found that species only respond to
inequity when they routinely cooperate with those who are not related to them.
Here I am speculating on what de
Waal and Brosnan have found and what it might mean. Animals that cooperate with non-kin face a
problem that animals who cooperate only with closely related individuals mostly
do not. Instincts for cooperation will
be selected for only if they advance the reproductive success of the
cooperator. If cooperative associations
reap benefits that are not available to conspecific non-cooperators, then the
one will outbreed the other. The species
will evolve toward greater cooperation.
However, what is true between
the cooperators and non-cooperators will be true within the population of
cooperators if some routinely exploit others.
Let us consider an over-simplified scenario in which two version of a
key gene are evenly distributed across a population of cooperators. One version (RI1) codes for righteous
indignation whenever that animal doesn’t receive a fair share of the benefits
of cooperation and the other version of the gene (RI2) does not. Assuming that RI2 results in a smaller payoff
from cooperation (and it only has to be a very small difference) then RI2 will
gradually disappear from the general population.
The really neat thing about
this is that it doesn’t matter how big the payoff is. Whether the population is small or large,
struggling or flourishing, within the population of cooperators, the indignant
will increase and the complacent will wither away. So when someone says “it’s not the money, it’s
the principle of the thing”, they are expressing something that has a long
evolutionary history. An inherited sense
of morality will maintain itself in the population only if it cares as much
about the principle as the profit.
The evolution of obligation is
rather more difficult. It is easier to
see why an animal would be offended by a smaller share than feel an obligation
to share when she has more than her partner.
Responding to getting less than a partner is not the only
aspect of fairness. For a true sense of fairness, it also matters if you get
more. Brosnan and de Waal hypothesize that individuals should be willing to
give up a benefit in order to reach equal outcomes and stabilize valuable,
long-term cooperative relationships. Thus far, this has only been found in
humans and their closest relatives, the apes.
A willingness to share
equitably with others when you could take more for yourself means that you are
(more or less consciously) concerned about maintain a reputation as a good
cooperator. That requires a more
sophisticated psychology than we see in most primates.
I close by noting that Plato
was right. The idea of justice is as
real as the idea of a triangle. The one
governs the architecture of certain animal societies as much as the other
governs the architecture of roofs.
