"PROVIDING for relatives comes more naturally than reaching out to strangers. Nevertheless, it may be worth being kind to people outside the family as the favour might be reciprocated in future. But when it comes to anonymous benevolence, directed to causes that, unlike people, can give nothing in return, what could motivate a donor? The answer, according to neuroscience, is that it feels good."..more there

ed: this might also explain why FOSS advocates can get so passionate about it, it feels good and is addictive, as well as being quite practical.