Are people selfish by nature? Does the progress of human society depend on competition or reciprocity? Perhaps some will answer that people are selfish by nature, and human social progress depends on competition. According to economists, our function in the world is to consume and produce. And according to biologists, the top priority for humans is to survive and reproduce. Behind both views seems to lie a central logic of necessary competition.

However, the nature teaches us some lessons about empathy and sympathy...