As the new adaptation took hold, the adaptive value of teeth decreased.

随着新适应的发生，牙齿的适应 值下降。

This is probably because, before brood parasitism appeared, responding would have likely had no adaptive value.

这可能是因为，在巢寄生现象出现之前，反应可能没有适应性价值。

There's all sorts of things a body will do that have no adaptive value, rather just accidents.

身体会做各种各样的事情，这些事情没有适应性价值，而只是偶然的。