Altruism is an ethical theory, which generally refers to the life attitude and behavior principle of putting social interests first and sacrificing personal interests for social interests. It refers to those behaviors that increase the survival chances and reproductive success rate of other individuals at the expense of their own survival and reproduction. Some are altruism at the phenotypic level; Some are altruistic at the genotype level; Some are completely altruistic behaviors, that is, both phenotype and genotype are altruistic. -Excerpted from Baidu Encyclopedia