Personal response

This passage is about the process of studying the goodness. Charles Darwin had observed that worker bees sacrificed themselves to protect their hives. From this observation, he was confused about the animal altruism. After years, a theory was established to explain the altruism that, animals would sacrifice to save their blood relatives. Later, however, arguments flared up. Some believed that all goodness could be resulted from genetic relation, while some claimed that goodness and genetic relation are utterly segregated. In 1963, Hamilton found came up with a formula explaining the relationship of the genetic relatedness between individuals, the cost of an act of goodness, and the privilege that one gained from others. This theory claimed that, if the cost of altruism could bring enough blood relatives benefit, then altruism emanates.
There is another category of reciprocity includes altruism. Individuals are usually willing to be altruistic to those who had helped them. Bill Hamilton and Robert axelrod fomalized the models behind the evolution of reciprocity. In 1981, they even used a mathematical technique to predict the time of reciprocal altruism to evolve.
In my view, Hamilton had explained the goodness in natural science quite well. But I think when humans are helping others, it is not only for genetic relatedness or reciprocity. It is quite common to see people helping those they have never met or known. They are altruistic because there is love their heart. And their actions of kindness spread out love in the human society.