Small but big difference between wolves and dogs

There are, of course, many dif­fer­ences between wolves and dogs. Some are cog­nit­ive, such as a wolf’s will­ing­ness to be trained, while oth­ers in­clude phys­ic­al traits such as the predator’s ex­traordin­ar­ily long legs and huge paws.

A lot of phys­ic­al char­ac­ter­ist­ics have been spe­cific­ally cul­tiv­ated in dogs to en­hance their ap­peal to hu­mans. For in­stance, many people are at­trac­ted to dogs with floppy ears and short muzzles so breed­ers have se­lect­ively en­cour­aged these traits. Wolves have these en­dear­ing fea­tures as pups but, as they ma­ture, their ears be­come erect and their snouts lengthen.

A re­cent study found an­oth­er small but sig­ni­fic­ant dif­fer­ence between wolves and some dogs – their eye­brow muscles.

Whether they own a dog or not, many people are fa­mil­i­ar with that sad sack stare some dogs seem to be able to sum­mon at will. This is the look guar­an­teed to tug firmly on the hu­man heartstrings. And to of­ten foster for­give­ness for any trans­gres­sions that may have occurred.

This im­plor­ing gaze is gen­er­ated by a dog’s abil­ity to move a prom­in­ent muscle that runs along the out­er edge of the eye up and inwards.

Dr. Juliane Kaminski, a psy­cho­lo­gist at the University of Portsmouth in England, dis­covered this while try­ing to un­der­stand why some dogs are ad­op­ted from an­im­al shel­ters soon­er than oth­ers. Apparently, it’s all in the eyes. Those who used their lev­at­or an­guli oculi me­dial­is muscle were first out the door to a new home.

Researchers then stud­ied the fa­cial mus­cu­lature of ca­da­vers of sev­er­al breeds of dogs, as well as those of wild grey wolves. They found a pro­nounced eye­brow muscle in all of the dogs but not the wolves.

This arc­tic beauty has a typ­ic­al wolfish gaze and no sign of sad sack eyes.

Unlike short snouts and floppy ears, the eye­brow muscle was not in­ten­tion­ally in­tro­duced by hu­mans but evolved nat­ur­ally over 20,000 years or more of the hu­man and dog relationship.

Kaminski, who has con­duc­ted sev­er­al stud­ies on the ways hu­mans and dogs com­mu­nic­ate, notes that eye­brows play an im­port­ant role in hu­man body lan­guage. And though it’s not known if dogs move their eye­brow muscle on pur­pose, the res­ult def­in­itely ap­pears to at­tract humans.