Michael Perelman wrote:
"Trade is a particular type of exchange.  If we exchange Christmas gifts, 
another species might interpret our behavior as trade.  If monkeys groom each 
other that might be trade if each paid the other $5.  Otherwise, it is more 
likely sociability rather than trade.  Symbiotic species are not trading 
anymore than the plant and animal life that make up a coral reef are trading.
Admittedly, trade can expand beyond market relations.  Kids can trade baseball
cards.  But the examples proposed here do not appear to be trade -- an activity 
in which both parties are aware of a mutual advantage."
 
How about adding cooperation and a measure of altruism to the motivational mix of
sentient beings? We are more or less familiar with the chimp-human connection. The
link is for an article that describes it in some detail.
 
http://select.nytimes.com/search/restricted/article?res=F60715FB3A5B0C748DDDAD0894DF404482
 
An excerpt: "Chimps display a remarkable range of behavior and talent. They make and
use simple tools, hunt in groups and engage in aggressive, violent acts. They are
social creatures that appear to be capable of empathy, altruism, self-awareness,
cooperation in problem solving and learning through example and experience. Chimps
even outperform humans in some memory tasks. "
 
And smart as we are as a species, we have managed with our trading prowess to create
havoc for others, including the chimps as the article mentions at the end. I would
be glad to post the text of the article if it is not accessible on other computers
due to restrictions by the newspaper.
 
Cheers,
 
Sumitra Shah