personal response of The Evolution of Goodness

According to the passage, the author tells us two explanations for why human beings are willing to do good to others. One is that altruism spread if there is enough genetic relatedness between you and the recipient and the cost of altruism is less than the benefit of it. The other explanation is called reciprocity, which means that individuals are willing to be altruistic to someone who will also be altruistic to them in return. However, these are only the answers can be found in evolutionary biology, there are also other explanations for altruism. I have seen someone helped people whom he did not know, this cannot be explained by the two reasons above. I think it is because every human being are born with a sympathetic heart, it is our nature to be altruistic.