Cooties and calico cats explained, finally

Seems like there's a bunch of stuff on the internets the last couple of days about the difference between women and men. It's a perennial favorite, I guess -- or maybe I'm just paying more attention. But the whole "where are all the women bloggers" question has been coming up again for the last few days. And Deborah Tannen's article in the LA Times [subscription required] generated some discussions.

Then the BBC weighed in with this interesting article about how female mammals are genetically more varied than males. It has to do with the difference between the X chromosome and the Y chromosome. Females, of course, have two X chromosomes and males have an X and a Y. And the X, "is much larger than the relatively puny Y, containing 1,098 genes to the Y's 78." Which explains why men are such weenies. Or why boys have cooties. Well, actually, it just means that females have more genetic material to work with than males. To be fair, lots of the genes are 'switched off' in females, but not all of them. And it's sort of random which ones are switched off.

So what does it mean? Well, for one thing, it explains why certain genetic disorders are passed on from mother to son: "Diseases on the X chromosome are usually expressed in males because they don't have a compensating copy of the gene on the second chromosome," said Dr. Mark Ross, the project leader at the Wellcome Trust Sanger Institute, UK -- but less frequently from mother to daughter.

It also provides another example of the female once again making up for the inadequacies of the male: "Although nobody quite knows why the Y chromosome shrank like it did, its decline was not catastrophic thanks to the X chromosome. In a sense, it does not matter too much that a male is missing genes on his Y chromosome, because he has equivalent copies on his X chromosome."

OK, they're just chromosomes. But I thought the article was interesting. Oh, and it also accounts for the phenomenon of calico cats.