Amazing article... especially when I consider that I'm working on one right now, that is questioning whether altruism (in the sense people imagine it) exists ;)

So let me play devil's advocate here and say that I can't see how the experiments you described imply altruism. Given that we evolved in groups of moderate sizes, of course one would expect that people help someone in distress instead of just fleeing the situation - such dishonorable behavior would severely tarnish one's reputation, even if the person-to-be-helped was a stranger. The study is just too simplistic and doesn't factor in important things like social status and tit-for-tat expectations, which surely play a role in "altruistic" decisions as well.

I am quite prepared to believe that the person who's helping believes he or she does it for altruistic reasons, but I think more realistic is an explanation that includes some kind of concern about social status. I'm not convinced by the study you cited, but since this is a matter that interests me a lot, I'll definitely check your references and take a look what other studies Batson et al. came up with. As always, thanks for your efforts luke!