[footfootfoot]

I was told by my HS physics teacher that on siamese cats the dark ear points were little solar gain patches too assist with warming the ears at the outer extremities where the circulation wasn't so good.

Mind you, this is the same teacher who once had our art teacher convinced for several days that moving objects don't reflect light. (he proved this with a polaroid photograph of a moving object at an exposure too slow to record said moving object, the back ground was fine)