Did KoKo talk when she communicated her tooth ache by sign
language? I would say yes.
http://en.wikipedia.org/wiki/Koko_(gorilla)
Do meerkats engage in service exchange?
http://nationalzoo.si.edu/Publications/ZooGoer/2007/1/meerkats.cfm
Trickier, but I would again say yes.
It has always fascinated me that so many economists wish
desperately to see humans as non-animals. This may well
explain some failures to understand human behavior.
http://www.bushorchimp.com/pics.html
Alan Isaac
PS None of this is meant to deny that the human ability to
handle abstraction (a *quantitative* difference, which
varies substantially among humans) has had qualitative
implications.