Dears,

Ross Emmett hits the nail on the head.  Trade is not mere reciprocity 
or coevolution, as important as these are in animals and plants (each 
fig tree has its own evolved wasp to be frutiful, etc.).  It's an 
economics of physical movement that would call such things "trade." 
As is argued in the book by the anthropologist Alan Page Fiske, 
Structures of Social Life: The Four Elementary Forms of Human 
Relations (1991, 1993), paralleled by Aro Klamer's insights into the 
four spheres (oikos, polis, agora, and the common good), trade is a 
"high" stage of interaction that involve unequal items.  Your frog 
for my jacknife, and 25 cents in coin.

And Ross also gets right what Smith said and we then forgot: language 
matters.  I just wrote a crazy draft paper on just this, trying to 
think through all the ways that the speakingness of human beings 
matters for the economy.  It's not prudence that is the key, Ross. 
Animals plan.  Grass is prudent.  It's talking, an adjunct of 
imagination that makes us traders.  Some people argue that evidence 
of the coming of high art and trade point to an invention of language 
in Africa perhaps as late as 60 BC (all such dates are under heated 
dispute: and you thought economics was a field of controversy), with 
Homo sapiens, better named Homo loquens, dominating Africa and 
bursting out of it with such a tool of cooperation. 

As Marvell said ("The Garden"):

The mind, that ocean where each kind
Does straight its own resemblance find ;
Yet it creates, transcending these,
Far other worlds, and other seas ;
Annihilating all that's made
To a green thought in a green shade.


Regards,


Deirdre McCloskey