The same scientist blames social pressures for the perception among many men and women that the sexes simply have different housekeeping and parenting standards, as couples often concede after living together for about 10 minutes.

To what end these labored studies?

Trying to figure out how to balance careers and family is a daunting endeavor. Couples are indeed hassled by modern stresses and those working outside the home have to be part magician to keep all the moveable parts in place. But somehow couples do work these things out without the aid of manifestos and PowerPoint presentations.

Or so one would think.

Gender theorists, meanwhile, may be saddled with a doomed task, trying to fit the square peg of reality into the round hole of hope. Sometimes things just are what they are. And wishful theory is no match for nature's stubborn ambition.

At the University of Virginia, Steven E. Rhoads -- author of "Taking Sex Differences Seriously" -- led a study of 184 tenure-track academic couples and found that even the most presumably enlightened people within our culture fall into the same patterns because, well, they just do. Women -- including university professors -- "simply like child care more than men and are reluctant to cede many child care duties to their husbands," concluded the study's authors.

Harvard zoologist E.O. Wilson wrote in his book "In Search of Nature" that "what is" in human nature -- and what may explain our rut of domestic inequity -- probably goes back to our Pleistocene hunter-gatherer forebears.

None of which means we can't change, but it might take some time. Genetic bias isn't as malleable as gender bias and is intense enough, writes Wilson, "to cause a substantial division of labor even in the most free and most egalitarian of future societies."

In the meantime, couples might toss their calculators and flowcharts and enjoy the ride. It's short -- and, on good days, messy.