What irks me is that the every time someone finds an evolutionary reason for something, it is just as easy to find an evolutionary reason to explain the opposite of it, which makes the explanation useless.

For example, "men evolved to be promiscuous because having many children gave the biggest chance at surviving offspring" makes sense until you realize "men evolved to be faithful because nurturing their children gave them the biggest chance at surviving offspring" makes just as much sense.

When your theory can explain everything, it can explain nothing.