This second chimpanzee is not a relative of the first chimpanzee and they've never seen each other before.

这只黑猩猩跟第一只黑猩猩,没有血缘关系,它们以前也从来没见过面。

耶鲁公开课 - 心理学导论课程节选

Even if animals are unrelated, they are nice to one another.

即使没有血缘关系的动物，它们也会友善地对待对方。

耶鲁公开课 - 心理学导论课程节选