It is said that biology is not destiny ...but that may be more of a hope than a statement of fact. There are many reasons that men--and yes, women too--may seek sexual gratification outside of their primary relationship. But there is also a fundamental difference between men and women that should not be overlooked.

Biologically, a woman's investment in reproduction far exceeds that of a man. She carries the developing life within her for nine months--and during that period she may become I'll with morning sickness. She will likely be unable to do certain tasks that she previously performed without giving the matter a second thought. And she will definitely be more vulnerable.

Historically, after the child arrives, she needed to nurse him or her for the first year or so, and then continued the nurturing process for a long period afterward. Her chances of succeeding--of ensuring that her DNA survives for another generation--increased dramatically if she had a committed partner to protect her and their offspring and, quite literally, "bring home the bacon."

A man, on the other hand, was best able to disseminate his DNA by having intercourse with as many women as possible, as often as possible (And if the women that he impregnated had other men to protect and support them, that was pure bonus.)

We may consciously choose to pursue an extramarital liaison because we are bored at home, or for the pure excitement of it all ... but are those the real reasons? Or are we simply yielding to unconscious drives that we not only fail to understand--but also fail to recognize.

It obviously isn't fair, but there is good reason to say that men, collectively, have more of a propensity to seek out multiple partners than women do (and yes, I certainly grant that there are multitudes of exceptions). Admitting this, it seems that perhaps we need to question the relatively recent embrace of monogamy, and the assumption that love or commitment necessarily requires sexual fidelity.