joy of learning

Sometimes a simple scientific fact explains something you've observed all your life and never understood the reason why.

My friend Laura was talking this morning about her Siamese or part-Siamese cat, Evander

(cat tax, but he's bigger and more grown-up than this now - this is from early August)



Anyway, she noted that she was going to have to get him neutered soon, and that "I never realized that on male Siamese cats, the balls are a "point" and get a darker color like the ears"

And because I had just discussed temperature-dependent gene activation in intro bio (and Siamese cats are an excellent example for that), I had to drop a little science in  my Twitter feed:

here are the basics. Tyrosinase is a precursor to melanin, the dark pigment that lots of mammals (including humans*) have


(*there are really two forms - at least - in humans. Eumelanin, or "true melanin" is the dark brownish melanin most of us have - some in bigger quantities than others - and pheomelanin is a more reddish-toned form that the people with bright "red" hair and freckles have - information here - and that also explains why I, a hazel-eyed person, tends to be v. light sensitive, especially compared to people with darker eyes: I have less eye-melanin to protect me!)

But anyway. In Siamese cats, the production of melanin is only triggered at cooler temperatures. Sometimes it is called "temperature dependent albinism."

Which leads me to the thing I learned today, which makes so much sense now but what was something I always wondered about:

Why are newborn Siamese kittens white, and only develop their points over time?

It's because of mama's womb temperature! the kits are warm, so they come out white, it's only over time they develop points.

Also, older cats can gradually change color. I know when Patty (one of my parents' old cats) went hyperthyroid, she got lighter over time from the higher body temperature she was running. And apparently the temperature where they live can affect them - the experiment in that first cat link was about shaving Siamese cats, keeping them in a cool room, but using bandages to insulate parts of their body so those parts grew in lighter.

And all this from a friend's throwaway joke about cat nuts...