Not that I've read the whole thread, but just want to make sure it's noted that economies based on generosity can certainly work on a small scale (ie, maybe a few hundred individuals) where each member more or less has some level of direct interaction with a non-trivial percentage of the total number of members. Extend beyond that size, and some basics of human nature (self-interest, devaluing the lives and rights of those who aren't close to you versus those who are, family allegiance, etc) take over that make such systems break down.
This makes a lot of sense to me.
It also reinforces that different aspects of humans take precedence in different situations. For example, there are different relationships within a family than there are in a local community and again in a global marketplace.
I guess what interests me, in the context of this thread, is whether we've evolved socially and technologically to scale that generosity aspect to a larger economy. I think Marx talked about a progression of revolutions from primitive communism -> feudalism -> capitalism -> advanced communism. Perhaps he had a similar idea in mind.
(Coincidently, I just came across the following quote: "Self-interest is but the survival of the animal in us. Humanity only begins for man with self-surrender." — Henri-Frédéric Amiel)