in the experiment is test them on their behavior towards humans. That’s it, that’s the only thing they ever select on. But what’s happened over the generations is that lots of other changes have occurred besides getting calmer and tamer animals. Early on, for example, some of the first changes were that the animals had curlier, bushier tails, the sort of tails that you imagine when you think of a dog wagging their tail because they’re excited to see you. Some of the animals began to show droopier, floppier ears. In addition, they began to see a much more mutt-like kind of mottled fur color.” There were also differences in stress hormones that showed the foxes were less stressed.
It is possible that some of the features we see in dogs are also by-products of domestication. However, another possibility is that along the way, we have sometimes selected for some of these features. To test this idea, scientists looked at one of the baby-like features in many dogs, the eyes. The study, published in PLOS ONE, looked at a facial expression by which dogs raise the inside of the eyebrow, making the eyes look bigger.2 The researchers enlisted the help of four dog rehoming centers, and filmed the dogs for two minutes with an experimenter standing by the kennel. They counted how many times the dogs made this expression during that time. Then they waited to see how long it took for the dogs to be adopted. The results showed that dogs who made this eyebrow movement five times within the two-minute period were adopted in fifty days, compared with thirty-five days if they did it ten times, and twenty-eight days if they did it fifteen times. It seems the baby-like eyebrow movement results in people being more drawn to those dogs. This was the first time scientists demonstrated a link between the baby-like features of a dog and people’s active selection of a dog.
HOW FASHION AFFECTS THE DOGS WE CHOOSE
BIOLOGY IS ONLY part of the story. Fashion affects breed popularity too. Featuring a particular breed of dog in the movies can increase its popularity for up to ten years afterward, according to a study in PLOS ONE that looked at dog-related movies from 1927 to 2004 and corresponding Kennel Club registrations.3 The release of films such as 101 Dalmatians and The Shaggy Dog were followed by huge increases in the popularity of Dalmatians and Old English Sheepdogs, respectively. And the “movie effect” still holds even if the breed had been decreasing in general popularity before the film was released.
A review of dog breed registrations from 1926 to 2005, published in PLOS ONE, found the popularity of a breed is not affected by the breed’s health, a longer lifespan, or better behavior (such as trainability, fearfulness, or aggression).4 In other words, pet-keeping does not just have a biological explanation but is also socially mediated, according to a study in Animal Behavior and Cognition.5 Just appearing in the media does not guarantee a breed’s popularity, however. For example, winning Best in Show at the prestigious and televised Westminster Kennel Club Dog Show does not usually have an effect, as reported in the Journal of the American Veterinary Medical Association.6
Dr. Hal Herzog is a professor emeritus of psychology and author of Some We Love, Some We Hate, Some We Eat: Why It’s So Hard to Think Straight about Animals who has spent over three decades investigating our interactions with animals, and who was involved in this research on the popularity of dog breeds. He told me this research had a profound effect on his own views about the role of biology versus culture. “For many, many years I’ve considered myself an evolutionary psychologist and I still do, but I really strongly believed that most of our behavior was determined by biological factors that shaped the minds of our ancestors. And I no longer believe that. And the real key to changing my mind on that is I studied how people choose breeds of dogs for pets. And what I realized is that the role of culture was really much more important than I had realized.”
Trends in dog choices are not necessarily good for dogs, as with the increased popularity of dogs with squashed faces, called brachycephalic features, such as French Bulldogs.7 Brachycephalic dogs can suffer medical problems including respiratory, eye, and skin issues as a result of their looks. Several of these breeds (French Bulldogs, Bulldogs, and Pugs) are amongst the most popular breeds in the United States, Canada, and the United Kingdom (see table).
The most popular dog breeds in the USA, Canada, and the UK in 2018
| USA | CANADA | UK | |
| 1 | Retriever (Labrador) | Labrador Retriever | French Bulldog |
| 2 | German Shepherd Dog | German Shepherd Dog | Retriever (Labrador) |
| 3 | Retriever (Golden) | Golden Retriever | Spaniel (Cocker) |
| 4 | French Bulldog | Poodle | Bulldog |
| 5 | Bulldog | French Bulldog | Spaniel (English Springer) |
| 6 | Beagle | Havanese | Pug |
| 7 | Poodle | Shetland Sheepdog | Retriever (Golden) |
| 8 | Rottweiler | Australian Shepherd | German Shepherd Dog |
| 9 | Pointer (German Short-Haired) | Bernese Mountain Dog | Dachshund (Miniature Smooth-haired) |
| 10 | Yorkshire Terrier | Portuguese Water Dog | Miniature Schnauzer |
Source: Information from the American Kennel Club, Canadian Kennel Club, and Kennel Club.8
Dr. Jessica Hekman, a veterinarian who studies the role of genetics and the environment on dog personality at Darwin’s Ark, recommends breed clubs support outcrossing projects. Instead of breeding dogs that are related to each other, outcrossing means mating two completely unrelated dogs (that is, ones that have no relations within a four-generation pedigree). This can bring in new variants of genes that will improve the health of the breed and help prevent problems due to inbreeding.
“WE CAN MAKE the world better for dogs by making dogs who fit into the world better. I would love to see dog owners draw a line in the sand and insist on dogs with muzzles long enough to let them breathe normally, or dogs who are not born with a 60 percent chance of developing cancer at some point in their lives due to their breed, or dogs whose heads are not too big for them to be born without a C-section. I’d love to see more breeders taking matters into their own hands and starting to experiment with how we breed dogs instead of continuing to use dogs from within breeds lacking in genetic diversity. I’d love to see more breed clubs supporting outcrossing projects to bring an influx of genetic diversity and healthy alleles into their breed. I’d love more dog lovers to become aware of the problems with how we breed dogs—how even the
