New study pinpoints genetic origin of short-legged dogs

There's plenty of evidence that Mother Nature has a sense of humor. You only need to look at the giraffe or the platypus to see support of her taste for the absurd. Also consider the dachshund, that hodgepodge of dog parts that seems to be a combination of inflated and shrunken versions of itself.

Science, of course, provides us evolutionary reasons for creatures' unique appearances. Now research has identified a specific genetic occurrence that seems to account for the distinctive short and curved legs typical of dachshunds, corgis and at least 17 other dog breeds. A team of experts from the National Human Genome Research Institute (NHGRI) has recognized a genetic signature particular to such breeds.

NHGRI scientific director Eric Green, M.D., Ph.D., notes that all species carry within their genomes detailed documents of evolution. By studying these blueprints, researchers have determined that short-legged dogs have a common variation in their DNA code, an extra bit of information called a retrogene-in this case a growth disorder-which developed through a process called reverse transcription.

What is perhaps most important about this discovery is a new understanding of the nature of retrogenes. Previously they had been considered crucial in species divergence, not in sustained change within one species. And this revelation may impact knowledge of human biological development. With one-third of human hypochondroplasia (also known as dwarfism) cases unsolved, these findings point to a gene that may unravel the remaining mystery.

So, next time you see a vertically challenged dog, don't scoff. There may be important evolutionary data in those little legs.