Dogs’ faces are structured for complex expression in a way that wolves’ aren’t, thanks to a special pair of muscles framing their eyes, The Atlantic reports.
Those muscles are responsible for that “adopt me” look that dogs can pull by raising their inner eyebrows.
According to a paper published this week in the Proceedings of the National Academy of Sciences, it’s the first biological evidence scientists have found that domesticated dogs might have evolved a specialized ability used specifically to communicate with humans.
By evolutionary standards, according to the article, this has been remarkably short time frame for two new facial muscles to develop. A pretty powerful force must be at work for a species to change that quickly; and that’s where humans come in.