The dog (Canis familiaris or Canis lupus familiaris as a subspecies of the wolf) is a carnivorous mammal belonging to the canid family that evolved alongside human societies in different cultures for over 30,000 years. Currently, it is estimated that there are around 1 billion dogs in the world and over 300 recognized breeds, in addition to many others in the process of classification.
Throughout the centuries, selective breeding allowed for the development of breeds with specific abilities for tasks such as herding, hunting, companionship, or protection. However, a recent study by Chapman University (USA) questions the relationship between skull shape and functional specialization in canine breeds.
The researchers analyzed 117 museum specimens, generating 3D reconstructions of skulls belonging to 41 domestic breeds and 18 wild subspecies. Their goal was to determine if there were clear morphological differences among dogs selected for specific tasks, such as those used by law enforcement or the military.
The study revealed that the skull structures of these breeds did not significantly differ from those without specific functions, nor from those of wolves and coyotes. Only some companion breeds exhibited distinctive features related to extremely short muzzles.
Domesticated dogs.</caption]
Does shape influence functionality?
If selective breeding based on bone structure were effective, breeds bred for specific tasks would be expected to show a differentiated cranial pattern. However, the study’s results indicate that this is not the case.
“Our findings suggest that the selection of specialized skull shapes has not had a significant impact on breed functionality,” explained Nicholas Hebdon, lead author of the study published in Science Advances. “Instead, it seems that breeding has been more effective in selecting personality traits and behaviors that predispose dogs to certain tasks, making them more efficient in them.”
Perception of physical differences in different dog breeds
The apparent distinction between breeds in terms of shape and function is due to the fact that morphological variability is evenly distributed among different groups, without a clear pattern. “It’s not that there is no variation, but that it does not follow a predictable logic in relation to functional specialization,” clarified Hebdon.
Consequently, the selection of specific physical traits, such as muzzle length, does not seem to be linked to better performance in certain tasks. For example, there are dogs with wide or deep muzzles that are not used for tracking, while others without these characteristics are employed in these functions. According to Hebdon, the key factor lies not in bone structure, but in cognitive and behavioral traits.
Dogs.
Artificial selection in dog breeding
The selective breeding of dogs followed a complex evolutionary process, influenced by both observation and tradition. Initially, breeders crossed dogs with outstanding abilities in certain tasks, leading to the perception of a relationship between form and function. Over time, this idea was reinforced, becoming a selection criterion, although in reality, other less evident factors could have influenced the success of certain breeds.
“I am surprised by how little we understand about dogs, despite their importance in our lives. If this happens with a species so close to us, imagine how much we do not know about other species,” reflected Hebdon.
The research team plans to continue exploring the relationship between form and function in other species, although Hebdon states that there is still much to discover about the evolution of dogs and their differences from other wild canids.
Differences between domestic and wild dogs
Domestic dogs are genetically adapted to live with humans, while wild dogs live in a natural state and stay away from human intervention.
Characteristics of domestic dogs
- They are accustomed to human presence
- They feed on what their owners give them
- They are selected for their docility
Characteristics of wild dogs
- They live in a natural state, away from human intervention
- They mainly feed on carrion
- They may have larger heads in proportion to their bodies
- They may have larger fangs than domestic dogs
- They may have shorter muzzles and fewer teeth than domestic dogs
Wild dogs can be domesticated, but they are not genetically adapted to live with humans.
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