Good topic, phg. I believe in recipricol altruism because it makes perfectly good sense, but I also believe that there is pure altruism that transcends our selfish instinct and this purity is what ancient religion was rooting for constantly. Jesus (as an example) was aware of this when he taught that we should do good deeds but never do it in public or boast about it. He was teaching that, by doing this, we are eliminating our selfish desires and touching upon this purity which exists and can be embraced, giving us an opportunity to find the light within us.