Adam Smith in discussing man's propensity to 'truck, barter and exchange' famously said: "Nobody ever saw a dog make a fair and deliberate exchange of one bone for another with another dog." We humans are social creatures, we talk, we haggle, we trade.
Our ability to thrive and lead flourshing lives is a by-product of the world created by individuals realizing the great gains from social cooperation under the division of labor. Figuring out what 'rules of the social game' will enable us to realize peaceful cooperation and productive specialization among individuals is one of the primary tasks of political economy. In short, as social creatures we require social rules that minimize conflict and maximize cooperation.
A caricature of economic man, however, is anything but social. Instead, homoeconomicus is depicted as an isolated creature who is able to calculate costs and benefits instaneously and accurately. But it turns out, actually that isolated creatures would have an extremely difficult time performing such calculations and thus would be unable to see the benefits of exchange, specialization, and social cooperation. They instead would when confronted with other humans behave not unlike Smith's dogs.
What can we learn from the study of the impact of orphan's lonely beginnings for the study of economics and human sociability?