What if everything we've come to believe about the male brain is wrong? What it men are not, as conventional/casual wisdom suggests, genetically predisposed to dip their sex-obsessed pen in every well they can find?
Don't worry, your understanding of the world isn't totally blown: The male brain's "area for sexual pursuit" is still 2.5 times greater than that of the female brain. But according to neuropsychiatrist Dr. Louann Brizendine, author of The Male Brain, men are still naturally inclined to search for a partner and effectively mate for life. Well, some men are, anyhow — it depends on their vasopressin receptor gene.
Take the vole, if you will. The prairie vole is monogamous and mates for life, even when tempted by hot female voles later in life. The montane vole, however, is a fuck-and-run kind of vole — he mates and is gone before morning (and really, doesn't the montane vole just look like a cad?). Worth noting: The monogamous prairie vole has a "long version" of the aforementioned vasopressin receptor gene, whereas the montane vole has a "short version." And when the brain of the promiscuous montane vole was injected with the long-version gene from his prairie cousin, the montane vole became monogamous. Just like that!
In humans they've identified around 17 different lengths of the vasopressin receptor gene, and studies echo the vole experiment's findings: Men with longer versions of the gene in question tend to be in happy, successful marriages, whereas the guys with the shorter gene are more likely to be bachelors.
My personal experience has been that some guys are simply the nesting type. I always found these men a little suspect; if he's so ready to settle down from the get-go, isn't it inevitable that he'll want to sow some wild, sex-fueled oats later? Sure, these are my own personal insecurities — but knowing there's some science to suggest that a guy isn't necessarily too good to be true might be a bit reassuring to anyone.
But if you sleep with a guy by the, say, third date, this information makes a pretty strong case for genetic testing by the sixth. Hell, why not have guys automatically tested before they sign up for Match.com or J-Date? Seems like a relevant stat for the "personal info" section. Or, if you two are truly smitten and will go the distance to make things work, maybe gene-replacement therapy will be a viable option. Think of the heartbreak spared, the efficiency gained!