Why only female cats are tortoiseshell or calico


Carolyn Brown’s lab at the University of British Columbia in Vancouver studies X chromosome inactivation, which prevents females (XX) from getting an overdose of the proteins produced by the X chromosome, compared to males (XY). This phenomenon explains why (with rare exceptions) only female cats are bi- or tricolor.

Go to the link to see the slideshow gallery of tortie and calico kitties. Crucially, THE CATS IN THESE PHOTOS ARE NOT LAB CATS. Brown’s lab doesn’t study cats. These are shelter cats photographed while awaiting adoption. Aren’t they beautiful?!

This doesn’t explain the “dilute” gene that makes some cats pink and blue instead of orange and black—or the white-spotting gene that turns a tortie into a tricolor calico. Lovers of science + cats, follow the links! And as a bonus, here’s Lumi, who somehow manages to be “all of the above”: tabby, Siamese, dilute (see the pale orange patches on her face and paw), and white-spotted.

The Change

(As I am experimenting with less-to-no Facebook, my cat observations and photos, including Sleep of the Day, will henceforth appear and accumulate here. While fewer people will see them, anyone who strays by here will be able to browse more of them. They will make a more obscure, but also more concentrated and lasting, record of my feline life.)

When you were a child, wasn’t the changing of seasons a grand shifting of the scenery? As in a theatre with four acts, you could almost hear the grinding of the gears deep under the stage and the rumbling of the sets as the old one was withdrawn into the wings for another year and the new one slid into place and was unveiled.

It’s still a big deal for cats!  Because we were in Florida last winter and spring, Flighty reacted to the cold entering the window (yes, cold!) last night as if it was an invading animal of a strange species — a breeze-weasel, maybe? A breezel. When it touched her nose she startled back, went all low-slung, and advanced her head slowly, in caution-investigation mode, ready to bounce back at the slightest touch. If I had put a hand on her back just then she would have shot three feet into the air. (Only three. She’s fat.)

Now she’s begun to sneeze, and that’s weirding her out too: “Hey, what’s with my nose?!” She gave it a thorough washing. Just like all the people who are suddenly getting colds, the cats are vulnerable when the seasons change. In addition to sniffles, they often get a gut virus that J and I used to call “the fall disease.” They remind me what a big deal it really is. There are many layers to it: newness, beauty, and, deeper down, threat. All of life alerts and salutes this signal with mortal respect.

Aren’t They Divine? [Updated]

Cats are gravity’s Chosen People.  And their relationship with gravity is as intimate and casual as Israel’s with Jehovah: they challenge it, defy it, disdain it, nonetheless bask in its grace and protection, and collaborate with it to create acts of breathtaking improbability. A human dancer or acrobat, perhaps cast out of Gravity’s Garden of Eden when we left the trees, has to toil unceasingly by the sweat of his or her brow to earn a grudging fraction of the favor*.

On another note, Icepick just wrote to me:

Cats tolerate humans for food and shelter, but they love us for our hands. Nothing scratches a cat better than the human hand. Those fuzzy heads just curl up into palms as though the palm had no other purpose. God may well be feline, and we’re only here to serve their interests. (Which would just show that the cat deity has no more ability to control reality than the ape deity.)


* With one exception—although he did work like a slave to attain such transcendence:

While Gene Kelly sparred heroically in a mighty battle with gravity — like Atlas, he held the world aloft, and you knew it — Astaire simply sidestepped the fight and actually came down upon gravity rather than trudging up it like most mortals.

~ Toni Bentley