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Evolution of facial muscle anatomy in dogs

By J. Kaminski, B. M. Waller, R. Diogo, A. Hartstone-Rose, A. M. Burrows

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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.

Publication Title Proc Natl Acad Sci U S A
Volume 116
Issue 29
Pages 14677-14681
ISBN/ISSN 0027-8424
DOI 10.1073/pnas.1820653116
Language eng
Notes 1091-6490Kaminski, JulianeWaller, Bridget MOrcid: 0000-0001-6303-7458Diogo, RuiHartstone-Rose, AdamOrcid: 0000-0001-5307-5573Burrows, Anne MJournal ArticleUnited StatesProc Natl Acad Sci U S A. 2019 Jul 16;116(29):14677-14681. doi: 10.1073/pnas.1820653116. Epub 2019 Jun 17.
Author Address Centre for Comparative and Evolutionary Psychology, Department of Psychology, University of Portsmouth, Portsmouth P01 2DY, United Kingdom; for Comparative and Evolutionary Psychology, Department of Psychology, University of Portsmouth, Portsmouth P01 2DY, United Kingdom.Department of Anatomy, Howard University College of Medicine, Washington, DC 20059.Department of Biological Sciences, North Carolina State University, Raleigh, NC 27695.Department of Physical Therapy, Duquesne University, Pittsburgh, PA 15228.
Cite this work

Researchers should cite this work as follows:

  1. Animal physiology
  2. Animals
  3. Behavior and behavior mechanisms
  4. Bonds
  5. Dogs
  6. Domestic animals
  7. Domestication
  8. Face
  9. Females
  10. Genetics
  11. Humans
  12. Selection
  13. Wolves