display | more...
The Rhodesian Ridgeback, a hunting dog whose path of descent passes through numerous breeds, is perhaps most remarkable for its distinct place in evolutionary biology. It is well known that all dogs are descended from wolves. But no kind of wolf sports a pronounced counter-whorl ridge along their back. And in fact, none of the other dogs which make up the ancestry of the Rhodesian Ridgeback regularly have such a ridge either. The African Khoikhoi occasionally presents a minimal ridge -- but in that forebear, the feature is associated with genetic deficiencies. In the tawny, muscled frame of the Ridgeback, the ridge is far more prominent, but is no deficiency, and not related to any health problems in the animal. (And in fact, studies have shown that this breed on average has fewer genetically traced health problems than other breeds.)

The ridge of the Rhodesian Ridgeback is, simply put, a new genetic feature, a new piece of information welling up in the DNA. An addition formed from the tireless process of random mutation for generation after generation. And, critically, it is one which arose and achieved morphological stability within a period of a few hundred years. With evolution having hundreds of millions of years to work with, the observable establishment of new information in the anatomy within a few hundred of those leaves lots and lots and lots of time for things like the sea cucumber to eventually end up being things like the wombat and the porcupine and the lowland gorilla. Oh, and, naturally, the Rhodesian Ridgeback.