a woman or women who is not his spouse. But does that constitute mental cheating? I don't know that it does. If I read a story about a child molester and think to myself he should be put to death for his crime did I murder mentally? I think thinking is just that - thinking. It is not actually acting and so while all men might sooner or later think sexually about someone other than a mate I don't think it is a big deal; it just seems to be something we do. It seems to be a part of "maleness".

It might be said that true lusting in one's mind is somethign a little deeper and might be indicative of something akin to cheating mentally. By lusting I mean the constant repeat focused attention on sexually thinking about another person other than a man's spouse.

However all of that works out I want to say this about evolution. Evolution and (my field) psychology may tell us how we often appear to act but it does not tell us how we must act. Probably the most essential part of being human is our ability to change our mind and thus our course of action. While certain sexual practices such as cheating may have evolved in a psychological paradigm that increases our (males' chances of passing on genes it is also safe to say that we are continuing to evolve and that falling back on the old "evolution made me do it" excuse is pretty lame.

So, men might have some kind of evolutionary urge to cheat but it doesn't mean we have to and it doesn't mean we should.