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     http://www.sciencedaily.com/releases/2008/01/
     080130092136.htm   
Why Don't Chimpanzees Like To Barter Food?

Researchers examined the circumstances under which chimpanzees, our
closest relatives, will exchange one inherently valuable commodity (an
apple slice) for another (a grape), which is what early humans must
have somehow learned to do. (Credit: iStockphoto/Nicola Stratford)

ScienceDaily (Feb. 5, 2008) — For thousands of years, human beings
have relied on commodity barter as an essential aspect of their lives.
It is the behavior that allows specialized professions, as one
individual gives up some of what he has reaped to exchange with
another for something different. In this way, both individuals end up
better off. Despite the importance of this behavior, little is known
about how barter evolved and developed.

This study is the first to examine the circumstances under which
chimpanzees, our closest relatives, will exchange one inherently
valuable commodity (an apple slice) for another (a grape), which is
what early humans must have somehow learned to do. Economists believe
that commodity barter is one of the most basic precursors to economic
specialization, which we observe in humans but not in other primate
species. First of all, the researchers found that chimpanzees often
did not spontaneously barter food items, but needed to be trained to
engage in commodity barter. Moreover, even after the chimpanzees had
been trained to do barters with reliable human trading partners, they
were reluctant to engage in extreme deals in which a very good
commodity (apple slices) had to be sacrificed in order to get an even
more preferred commodity (grapes).

Prior animal behavior studies have largely examined chimpanzees'
willingness to trade tokens for valuable commodities. Tokens do not
exist in nature, and lack inherent value, so a chimpanzee's
willingness to trade a token for a valuable commodity, such as a
grape, may say little about chimpanzee behavior outside the laboratory.

In a series of experiments, chimpanzees at two different facilities
were given items of food and then offered the chance to exchange them
for other food items. A collaboration of researchers from Georgia
State University, the University of California, Los Angeles, and the
U.T. M.D. Anderson Cancer Center found that the chimpanzees, once they
were trained, were willing to barter food with humans, but if they
could gain something significantly better -- say, giving up carrots
for much preferred grapes. Otherwise, they preferred to keep what they
had.

The observed chimpanzee behavior could be reasonable because
chimpanzees lack social systems to enforce deals and, as a society,
punish an individual that cheats its trading partner by running off
with both commodities. Also because of their lack of property
ownership norms, chimpanzees in nature do not store property and thus
would have little opportunity to trade commodities.

Nevertheless, as prior research has demonstrated, they do possess
highly active service economies. In their natural environment, only
current possessions are "owned," and the threat of losing what one has
is very high, so chimpanzees frequently possess nothing to trade.

"This reluctance to trade appears to be deeply ingrained in the
chimpanzee psyche," said one of the lead authors, Sarah Brosnan, an
assistant professor of psychology at Georgia State University.
"They're perfectly capable of barter, but they don't do so in a way
which will maximize their outcomes."

The other lead author, Professor Mark F. Grady, Director of UCLA's
Center for Law and Economics, commented: "I believe that chimpanzees
are reluctant to barter commodities mainly because they lack effective
ownership norms. These norms are especially costly to enforce, and for
this species the game has evidently not been worth the candle.
Fortunately, services can be protected without ownership norms, so
chimpanzees can and do trade services with each other. As chimpanzee
societies demonstrate, however, a service economy does not lead to the
same degree of economic specialization that we observe among humans."

The research could additionally shed light on the instances in which
humans also don't maximize their gains, Brosnan said.

The laboratory experiments for this study was conducted at Georgia
State's Language Research Center and the University of Texas M.D.
Anderson Cancer Center, and the much of the conceptual work was done
at UCLA's Center for Law and Economics.

Citation: Brosnan SF, Grady MF, Lambeth SP, Schapiro SJ, Beran MJ
(2008) Chimpanzee Autarky. PLoS One 3(1): e1518.
doi:10.1371/journal.pone.0001518 http://www.plosone.org/doi/pone.0001518


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