"Well, that's really nice. Everybody benefits,"

这很好所有蝙蝠都能受益
but this raises a puzzle

但是从进化论角度
from the evolutionary point of view.

这产生了一个问题
Remember, animals benefit more,

记住这样动物获益更多
and to this situation,

在这种情形下
animals benefit more by working together than by working alone.

动物们共同工作比单独工作获益更多
The benefits outweigh the costs.

益处超过代价
This is known as "Reciprocal altruism"

这被称作互惠利他主义
meaning my behavior to you,

指我对你的行为
my good behavior to you, my altruism for you,

我对你的帮助对你的利他主义
is predicated on the idea of reciprocation,

是建立在互惠的基础上
"I'll benefit from you."

我也会受惠于你