X-celling Over Men
By MAUREEN DOWD

Published: March 20, 2005

Men are always telling me not to generalize about them.

But a startling new study shows that science is backing me up here.

Research published last week in the journal Nature reveals that women are genetically more complex than scientists ever imagined, while men remain the simple creatures they appear.

"Alas," said one of the authors of the study, the Duke University genome expert Huntington Willard, "genetically speaking, if you've met one man, you've met them all. We are, I hate to say it, predictable. You can't say that about women. Men and women are farther apart than we ever knew. It's not Mars or Venus. It's Mars or Venus, Pluto, Jupiter and who knows what other planets."

Women are not only more different from men than we knew. Women are more different from each other than we knew - creatures of "infinite variety," as Shakespeare wrote.

"We poor men only have 45 chromosomes to do our work with because our 46th is the pathetic Y that has only a few genes which operate below the waist and above the knees," Dr. Willard observed. "In contrast, we now know that women have the full 46 chromosomes that they're getting work from and the 46th is a second X that is working at levels greater than we knew."

Dr. Willard and his co-author, Laura Carrel, a molecular biologist at the Pennsylvania State University College of Medicine, think that their discovery may help explain why the behavior and traits of men and women are so different; they may be hard-wired in the brain, in addition to being hormonal or cultural.

So is Lawrence Summers right after all? "Only time will tell," Dr. Willard laughs.

The researchers learned that a whopping 15 percent - 200 to 300 - of the genes on the second X chromosome in women, thought to be submissive and inert, lolling about on an evolutionary Victorian fainting couch, are active, giving women a significant increase in gene expression over men.

As the Times science reporter Nicholas Wade, who is writing a book about human evolution and genetics, explained it to me: "Women are mosaics, one could even say chimeras, in the sense that they are made up of two different kinds of cell. Whereas men are pure and uncomplicated, being made of just a single kind of cell throughout."

This means men's generalizations about women are correct, too. Women are inscrutable, changeable, crafty, idiosyncratic, a different species.

"Women's chromosomes have more complexity, which men view as unpredictability," said David Page, a molecular biologist and expert on sex evolution at the Whitehead Institute for Biomedical Research in Cambridge, Mass.

Known as Mr. Y, Dr. P calls himself "the defender of the rotting Y chromosome." He's referring to studies showing that the Y chromosome has been shedding genes willy-nilly for millions of years and is now a fraction of the size of its partner, the X chromosome. "The Y married up," he notes. "The X married down."

Size matters, so some experts have suggested that in 10 million years or even much sooner - 100,000 years - men could disappear, taking Maxim magazine, March Madness and cold pizza in the morning with them.

Dr. Page drolly conjures up a picture of the Y chromosome as "a slovenly beast," sitting in his favorite armchair, surrounded by the litter of old fast food takeout boxes.

"The Y wants to maintain himself but doesn't know how," he said. "He's falling apart, like the guy who can't manage to get a doctor's appointment or can't clean up the house or apartment unless his wife does it.

"I prefer to think of the Y as persevering and noble, not as the Rodney Dangerfield of the human genome."

Dr. Page says the Y - a refuge throughout evolution for any gene that is good for males and/or bad for females - has become "a mirror, a metaphor, a blank slate on which you can write anything you want to think about males." It has inspired cartoon gene maps that show the belching gene, the inability-to-remember-birthdays-and-anniversaries gene, the fascination-with-spiders-and-reptiles gene, the selective-hearing-loss-"Huh" gene, the inability-to-express-affection-on-the-phone gene.

The discovery about women's superior gene expression may answer the age-old question about why men have trouble expressing themselves: because their genes do.