Evolution of facial muscle anatomy in dogs

Domestication shaped wolves into dogs and transformed both their behavior and their anatomy. Here we show that, in only 33,000 y, domestication transformed the facial muscle anatomy of dogs specifically for facial communication with humans. Based on dissections of dog and wolf heads, we show that th...

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Bibliographic Details
Published in:Proceedings of the National Academy of Sciences - PNAS 2019-07, Vol.116 (29), p.14677-14681
Main Authors: Kaminski, Juliane, Waller, Bridget M., Diogo, Rui, Hartstone-Rose, Adam, Burrows, Anne M.
Format: Article
Language:English
Subjects:
Anatomy
Animals
Behavior, Animal - physiology
Biological Sciences
Bonding, Human-Pet
Canidae
Dogs
Dogs - physiology
Domestication
Eyebrows - physiology
Face
Facial Expression
Facial Muscles - anatomy & histology
Facial Muscles - physiology
Female
Humans
Muscles
Selection, Genetic
Wolves
Wolves - anatomy & histology
Wolves - physiology
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Summary:Domestication shaped wolves into dogs and transformed both their behavior and their anatomy. Here we show that, in only 33,000 y, domestication transformed the facial muscle anatomy of dogs specifically for facial communication with humans. Based on dissections of dog and wolf heads, we show that the levator anguli oculi medialis, a muscle responsible for raising the inner eyebrow intensely, is uniformly present in dogs but not in wolves. Behavioral data, collected from dogs and wolves, show that dogs produce the eyebrow movement significantly more often and with higher intensity than wolves do, with highest-intensity movements produced exclusively by dogs. Interestingly, this movement increases paedomorphism and resembles an expression that humans produce when sad, so its production in dogs may trigger a nurturing response in humans. We hypothesize that dogs with expressive eyebrows had a selection advantage and that “puppy dog eyes” are the result of selection based on humans’ preferences.
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.1820653116