From a psychological point then, animals have evolved to be nice to their kin, particularly their children, and particularly in birds and mammals.

从心理学角度看，动物进化趋向于对自己的亲人有益，特别是自己的孩子，以鸟类和哺乳类为代表。

耶鲁公开课 - 心理学导论课程节选