by the Way . . .

The fossil record of the cat family has long been difficult to classify, since without the fur there is little difference except size. In fact, until recently the main classification was by size: Little Cat, Big Cat, and B-B-B-Big Cat. Now each of the 37 species of cat has been assigned to its own branch of the family tree, based on studies of mitochondrial DNA.

These studies have also given greater insight into the evolution and migration of cats as the sea levels changed over time. Cats only migrate when the sea level falls and leaves dry land. You know how they are about water. It turns out that the youngest lineage, which includes the house cat, originated in the United States, and crossed over to Asia on the Bering land bridge. The seas rose for a while and the cats stayed put, and then fell again, opening the Bering bridge again. It is well know that humans migrated to the U.S. (and Alaska, which was not yet part of the U.S.) across the Bering bridge at that time. The researchers were surprised to find that the house cat came back across the bridge with them. There is some dispute about this finding, as anyone who has ever traveled with a cat can appreciate.