According to Morrill’s team, breed explains just a small fraction of the mind-boggling variation in behavior seen in the species that is dog—less than 10 percent. Which is to say, most of the mishmash can be attributed to something else.

In the UMass-Broad study, purebred golden and Labrador retrievers “tended to score exceptionally,” Karlsson told me, on people-friendly metrics—exactly as the AKC website says they should. But those effects evaporated when her team turned their lens to mutts with retriever ancestry, who are harder to typecast by appearance alone. (Most people, by the way, aren’t actually that good at correctly guessing a dog’s lineage.) Even after the researchers accounted for the mutts’ mixed heritage, they found that the part-retrievers weren’t any more eager to mingle than the average pooch. While friendly dogs are consider…

Ha! I always wondered about this.

…uthanized based on breed alone. Dogs who fall into the pit-bull category are a famous, and particularly controversial, example of this: Bred to fight other animals, they’ve acquired a reputation for violence and unpredictability, a stigma worsened, scholars have argued, by racism against America’s urban Black and Latino communities, to which the dogs were culturally linked in the mid-20th century. Some experts argue that caution around pit bulls is warranted, given their history; people who look at pictures of the dogs tend to rate them unfavorably. And yet, studies done by Alvarez, Zapata, and others have found that pit bulls don’t seem to be more aggressive or volatile than other dogs. If any dogs are a bit more apt …

I’ve argued with people about this but it’s very hard to get past “Oh come on, don’t tell me the leopard can change his spots” regardless of data.

At the end of the day, when my dog passed away, we got another of the same breed–less because I really believed she’d be similar than because it seemed like The Way that people discern these things. My acting like it matters even in this shrug of a way helps reify the whole deal.