EH.R: Is Trade Unique to Humans?

[McCully, Michael J.]

Female brown capuchin monkeys apparently have the ability to assess the value of objects and express their relative preferences, and can be taught to trade objects formally. 


This was reported here:

Brosnan, S.F., and F.B.M. de Waal. 2003. Monkeys reject unequal pay. Nature 425(Sept. 18):297-299. Abstract available at http://dx.doi.org/10.1038/nature01963 <http://dx.doi.org/10.1038/nature01963> .


and summarized here:

 
http://www.sciencenews.org/articles/20030920/fob5.asp <http://www.sciencenews.org/articles/20030920/fob5.asp> 


Sarah Brosnan and Frans de Waal did a study in which monkeys were given rock tokens and trained to give them back in exchange for food. 95% of the time, monkeys immediately gave back (low-valued) rocks for higher-valued food such as cucumber slices, if cucumber slices were what was available in the room. 


However, if a monkey saw an unrelated partner receiving a grape, when she herself was offered a cucumber slice, she would often refuse the trade. 

In individualized experiments without partners, the summary indicates when she could see both types of food and was offered cucumber slices instead of grapes, the monkey also tended to refuse the trade.

Of course this took place in a lab setting and involved training with respect to exchange. However, the monkeys were not trained with respect to which objects were more desirable. This seems to indicate at least a capacity for valuation and trade, in non-humans. Does the list agree?

 
Mike McCully

High Point University


 




Visit www.highpoint.edu ... At High Point University, every student receives an extraordinary education in a fun environment with caring people.