How costly altruism survives? The rescue of both cooperation and voluntary sharing

Living in the environment full of competition and risk, individuals are supposed to pursue private interests. Defectors avoid the cost of cooperation and usually earn more. So defection seems to prevail in the population under natural selection. However, the costly cooperation abounds both in biological systems and human society, which attracts the interest of scholars in many fields. Income sharing is a simple and effective means of promoting cooperation. But most sharing mechanisms at present highly rely on enforcement. Sharing is always costly for the sharers, as same as cooperating. So voluntary sharing hardly survives without a reasonable evolution mechanism. In this work, we studied the coevolution of sharing and cooperation and found the failure of traditional sharing mechanisms on maintaining voluntary sharing. To rescue the voluntary sharing and cooperation, we proposed a fresh form of sharing mechanism, Temporary Interest Community (TIC) mechanism. According to our simulations, TIC mechanism successful rescues both voluntary sharing and cooperation to some extent, but it never eliminates the defection completely. Sharing is conductive to cooperation, while the development of cooperation inhibits sharing among population instead. In addition, we have also observed that sharing in a visionary population is more frequent and stable. So strengthening the memory of the group may stimulate more cooperation.