Even though our favorite pet dogs are now well-domesticated, we can still catch glimpses of their primal past when we watch them devour a bone or hunt those pesky squirrels. Sadly, new research shows that the status of dogs in the human family may have had a rocky start, often leaving them to dodge physical harm and rely on scavenging.
Unfortunately, there is little research available on archaeological dog remains, making it difficult to compare patterns of skeletal damage. Researchers also lack sufficient records of human life and culture in the presence of canines; it seems that early tribes weren’t regularly recording details of dog domestication.
Researchers at the University of Alberta have begun to shed light on these practices by analyzing ancient dog teeth. In their recent PLOS ONE study, they describe canine dental specimens with extensive damage to teeth and bone, including tooth loss, trauma, and defects. The authors analyzed and compared these remains with wild canids, such as foxes, jackals, and wolves, to better understand early dog behavior and help interpret signs of trauma.
These weren’t just any dogs, though. The authors studied four main types of dental and skeletal damage from museum collections in Northern Canada and Russia (see the map above). Using remains from these northern locations allowed the researchers to investigate the unique challenges dogs face when living in cold climates, where hunting and sled driving were common. The authors focused on tooth loss and fractures, as well as traumatic lesions on the cranium or jaw bone.
Determining the cause of tooth damage can be tricky, but overall, they found that tooth loss occurred in a higher percentage of the dogs rather than wolves. More than that, the overall percentage of teeth lost (per dog) was also higher in the dog population. This indicates that human owners may have played a part in removing some teeth, perhaps to stop dogs from chewing their possessions or the ropes tethering them to their sleds.
Furthermore, dogs on the whole showed higher rates of tooth loss, fracture, and traumatic lesions compared to wolves from the same region (click to enlarge image above). Notably, tooth fracture was present in similar teeth within the mouths of different dogs. The higher prevalence of this trauma among the dogs could be explained by aspects of feeding, such as how their food was obtained, or the qualities (density, texture) of what they were chewing.
As an example, dogs likely received leftovers from human food and had to work their mouths harder to chew and extract nutrients from what was left. Given the geographic location, they may also have been fed whale blubber, or chunks of frozen meat with bones in them. These unlikely additions to their diet may have caused the higher frequency of tooth fracture or damage that was seen in the dog population compared to the wolves.
The rate of traumatic lesions on the jaw and skull of the dogs was also higher than those of free-roaming wolves. There is always the possibility that fighting between animals caused these lesions, especially on the skull and snout. However, the rates of scarring and the involvement of humans in the lives of these dogs suggests another explanation for this physical damage: a result of humans physically controlling the dogs.
If there’s one thing that’s evident from these results, it is that the life of a domesticated dog in our society was not always easy. Access to human-provided food gave the dogs some freedom from food stress but exposed them to other hazards posed by humans, such as weapons and controlling behavior. Although it was clearly a complicated and difficult transition for these animals to make, it is a glimpse into the history of the new human-dog bond we have today.
Dogs from these cold, hunting-driven climates were valued by us for their strength, hunting assistance, and ability to fend for themselves. We owe them for their commitment to us, and for sticking with us through better or potentially worse. Tonight, give Fido an extra soft treat and a hug.
Citation: Losey RJ, Jessup E, Nomokonova T, Sablin M (2014) Craniomandibular Trauma and Tooth Loss in Northern Dogs and Wolves: Implications for the Archaeological Study of Dog Husbandry and Domestication. PLoS ONE 9(6): e99746. doi:10.1371/journal.pone.0099746
Image 1: Wolf by Dennis Matheson
Image 2 & 3: Figure 1 and Figure 3 from the article
Image 4: Pug by Jon Clegg