A recent study of pit bull skulls using 3-D imaging technology has revealed that they have skull measurements that are more similar to the extinct canids in the genus Borophagus. Further analysis involving SNP technology revealed that the average of 24.6 percent ancestry that is from a canid that is neither wolf nor domestic dog.
Abbott Millard, a canid researcher with the Dog Origins Project, has performed the 3-D imaging research, which included 130 pit bull skulls. His a comparison with the measurements of the pit bull skulls with those of several extant and extinct canids.
“Our results show that pit bulls have skull morphology most similar to the extinct dogs of the genus Borophagus. These results were quite shocking because Borophagus has been classified with an extinct group of canids that were thought not be related to modern dogs at all,” said Millard.
However, knowing that canids have a tendency towards convergent evolution in skull morphology, it is quite possible that pit bulls, a breed known for its massive jaw strength, evolved similar jaws to the Borphagus through similar selection pressures.
Which is why the Dog Origins Project decided to do some research on pit bull DNA. The researchers used SNP chip technology, which allows for extensive genome-wide assays. Similar research has been used to disprove East Asian origins for the domestic dog and raised real questions about the taxonomic status of the red wolf.
Otto Klinger, lead geneticist at the Dog Origins Project, compared DNA from 20 pit bulls, 15 boxers, 4 dingoes, 6 wolves from 4 different regions in the Old World, 12 coyotes, and 3 golden jackals. Pit bulls were found to be mostly domestic dog in origin, but a large sample of their genetic material didn’t match any extant canid.
“It is possible that this mystery canid was actually an undocumented wolf subspecies, but the finding that pit bulls have similar skulls to the Borophagus raises intriguing questions. It could mean that the pit bull terrier developed in America was crossed with a relict population of Borophagus,” said Klinger, “There are many mentions of strange wolves in the colonial literature that might be very suggestive of Borophagus, and there are mentions of blocky-headed wolfdogs belonging to the Algonquin peoples of the Northeast. Maybe these dogs and wolves were the relict Borophagus. They certainly would have been great fighting dogs.”
The discovery of the hybrid origin for the pit bull, though, does raise some important questions.
Millard believes that these studies mean that pit bulls deserve their own species status:
“The hybrid origin of the pit bull strongly suggests that we should not be classifying pit bulls as part of the greater dog species. We propose that the scientific name for the new pit bull species be Canis horribilus. Pit bulls are the grizzly bears of the dog world, so we think that we should use the grizzly bear’s name [Ursus arctos horribilus] to define the pit bull.”
With this new definitive DNA research on pit bulls, breed specific legislation will now be much easier to enforce, and the Dog Origin Project plans on donating its findings to law enforcement to develop a definitive pit bull genetic test.
“Our research will now have a positive impact upon society. I can’t tell you how thrilled I am wih the possibilities!” said Klinger.
So we now know why pit bulls are so different from other dogs. They are hybrids with a mystery canid that might be a survivor from the days of the ancient Borophaginae.