I participated to a very nice ECCO seminar last week from Chris Exton (University of Limerick). He is investigating recent internet phenomena such as crowdsourcing and open-source, and tries to explain it from an evolutionary psychology perspective. He is linking it to altruism, a characteristic that, from an evolution point of view, is seen as positive for human society.
Altruism is usually for kin-members (we will sacrifice ourselves for the survival of our descendants), or at least there is a reward to it. When somebody is recognised as altruist, people tend to give to him, better than to somebody that never gives back. This interaction gives him notoriety, and he goes up in the society hierarchy.
But these new internet phenomena are asking people to give anonymously… and it works! Human nature is amazing, isn’t it? )