In her comment on this post, Deniz inquired if my cats weren't interested in the deer skull from a few weeks ago. Yes, of course.
After the skull was cleaned in hydrogen peroxide, I offered it to Marissa-Cat. Her initial response was to smell the skull carefully for a minute or two.
This was followed by head rubbing that lasted another minute or so. This sequence of events, careful smelling followed by head rubbing is a characteristic behavior of domesticated cats when confronted with a new object.
Why do cats rub? Cats have glands producing fatty secretions between their eyes and ears, around their lips and on their chins1. When they rub their heads against people, other cats or inanimate objects, they are apparently marking them with the secretions of those glands. In the picture above, Marissa-Cat appears to be using the glands between her eyes and ears.
But what is the function of scent-marking? The brief discussions of this behavior that I have read1, 2 do not offer clear answers. The imparting of a smell, if that is indeed what the cat is doing, on whatever it is rubbing against, may be the cat's way of accepting the thing, such as a deer skull, into its world. After the smelling and rubbing ritual is finished, the object now smells like the cat and so it is a part of the cat's world.
But this doesn't quite explain why Marissa-Cat gets very rubby-dubby against my legs when she is hungry.
1Turner, D.C. & Bateson, P. The domesticated cat: the biology of its behaviour. 1988.
2Morris, D. Cat watching. 1986.