Paedomorphism (or “neoteny”) is a fancy term for the retention of juvenile characteristics into adulthood. In terms of dogs then, paedomorphism is an adult dog keeping a puppylike appearance. A study published last week in PLOS ONE concludes that dogs with paedomorphic (or puppylike) facial expressions have an advantage.
While it is not known for sure how wolves became domesticated, one theory is that they underwent a process of self-domestication as tamer wolves were able to take advantage of scavenging opportunities around human settlements. It has been thought that the more puppy-like appearance and behavioral traits or modern dogs evolved as a result of the self-selection against aggression. However, this new study suggests that the evolution could be the result of our own preference for dogs with puppy-like facial features such as a shorter snout, large eyes and wider skull. This study focused in particular on dogs’ use of facial muscle contractions to raise the inner brow, resulting in a more juvenile appearance.
The experiment evaluated the adoption of shelter dogs, and concluded that “…dogs who produced a high frequency of facial movement to raise the inner brow were adopted more quickly from re-homing shelters.” This suggests that dogs may have evolved in response to a human preference for juvenile features of the face. It’s also possible that the adopters were responding to a perceived sadness which the brow lift may have conveyed in the dogs looking for adoption.