Fancy rat’s dumbo mutation and its manifestation in the skull

Domesticated rats, also known as fancy rats, are the exact same species as the wild ones: Rattus norvegicus. The process of domestication began in England around the 1800s and is attributed to Jack Black, the Royal Rat Catcher(AFRMA, 2015). Today having a rat as a pet is still frowned upon by many people, mostly because they are still associated with filth and diseases.

The fancy rat has been bred in order achieve different variations, which are basically rare mutations that have been made more common by breeding individuals with a set of genes that is more likely to produce said mutation. Some of these are as simple as different hair colours or different hair types(i.e. curly or longer hair) while others go beyond that like the tailless mutation which causes the rat to not grow a tail. One of the most common mutation that can be observed in fancy rat is the dumbo mutation. This mutation causes the rat’s ears to be positioned lower on the the head giving the rat a more cartoon look.

A regular fancy rat (top) and a dumbo (bottom).

Being an archaeology student specializing in zooarchaeology, animal bones fascinate me and about a year ago I started collecting them. I’ve had a cat skeleton and two rat skeletons, all of which I have donated to the university I study in. These two rats where my pets and I know that one of them was a dumbo and the other a regular rat, so I decided I wanted to find a way of telling them apart.

I contacted Paolo Viscardi and sent him a photo of both skulls. Although we didn’t manage to determine with certainty which is which, there is a good chance the one on the left belongs to the dumbo. As Paolo pointed out, the nuchal crest on the left skull has a slight extension. I also noticed that the point where the zigomatic process meets the temporal bone is lower on this one, both of these could explain the lower ears on a dumbo rat.

I will continue to collect rat skulls to try and have a better understanding of the physical alterations caused by the dumbo mutation. If you are a pet rat owner and have unburied your rats, please contact me and send me photos, or maybe even the skeleton. I’m also looking for skeletons of other animals.

References

AFRMA (2015) - The history of fancy rats.[ONLINE] Availble at: http://www.afrma.org/historyrat.htm. [Accessed 7 March 2015]

