Coats of Many Colors

Once again, I return to one of my favorite topics — cats.

I was inspired to write about cats again by a post that showed a picture of a friend’s new cat, which was all black, except for a few white hairs that appeared on the cat’s chest. I commented, “All black cats are required to have at least ten black hairs somewhere on their body. It’s a rule.” I do believe that, and nobody’s going to convince me otherwise.

Dan a never owned an all-black cat, but we have had one that was what’s called a “tuxedo cat,” all black except for a white bib and, in this case, little white feet and magnificent white whiskers.

As befits a cat wearing a tuxedo, she was very dignified and hated it when anything happened to offend her dignity. You could see that she was appalled.

(By the way, it’s not true that black cats are more likely to suffer human predation around Halloween, despite the rumors. It’s an Urban Legend. Shelters will let you adopt a black cat at any time of year, too. But I digress.)

We have owned black-and-white and gray-and-white cats, a couple of gray tabbies and a couple of orange tabbies, plus assorted calicos and tortoiseshells (calicos are actually a variety of tortoiseshell, with white added to the orange and black). I’m generally the one responsible for inviting the calicos and torties into our home, as I’ve always been attracted to their colors. Dan is partial to the orange-striped cats.

Calicos are particularly interesting because they are almost invariably females. Their tricolored fur is a result of genetics. The calico pattern is determined by two X chromosomes. An XY cat is a male and can’t have two copies of the calico gene required to express those colors of fur. Technically, a male cat can be calico if it has two X chromosomes and a Y, but this is very rare and a male calico is almost always sterile.

Another genetic trick that some cats have is heterochromia, or one eye a different color…