You know that face your dog makes, the one that’s a little bit quizzical, maybe a bit sad, a bit anticipatory, with the eyebrows slanted? Sometimes you think it says, “Don’t be sad. I can help.” Other times it quite clearly asks, “No salami for me?”
Scientists have not yet been able to translate the look, but they have given it a very serious label: “AU101: inner eyebrow raise.” And a team of evolutionary psychologists and anatomists reported Monday in Proceedings of the National Academy of Sciences that dogs make this face more often and way more intensely than wolves. In fact dogs, but not wolves, have a specific muscle that helps raise those brows.
The scientists hypothesize that humans have unconsciously favored eyebrow-raising dogs during fairly recent selective breeding. Dr. Burrows said that one tantalizing hint that could lead to future study was that one of the dogs, a Siberian husky, was more like the wolves and did not have the levator anguli oculi medialis.
I had a conversation the other day with a scientist (not a biologist, however) about when natural selection ended and breeding began for dogs. We didn't have any conclusions but we hypothesized it might be as recently as 8,000 years before present or as long ago as 40,000 YBP. This article suggests that it may be both, depending on the breed.