なぜ犬は忠誠心が強いのか？

Dogs are famous for their loyalty, but is this a true emotional bond or a survival instinct? Science sides with sentiment in this case.

Dogs live up to their title of “Man’s Best Friend,” but many pet owners wonder whether this devotion is the result of an emotional bond or if Fido is simply acting in his own self-interest. Science is on the side of sentiments in the case of canine loyalty.

To help us understand dogs’ devotion, it is useful to look back at canines and humans’ shared evolutionary history. Most researchers agree that mutual benefits led to the domestication of dogs, eventually leading to our modern-day companions. Leftover spoils from human hunts offered a ready source of food for wild dogs to scavenge and, over time, those canines more accepting of human proximity gained easier access to food. Selective breeding of these friendlier dogs may have played a role in shaping our pets, too, as dogs later filled roles as guard animals and companions. Evidence shows humans buried dogs near their settlements as early as roughly 13,000 years ago.

With the advent of the modern-day canine came changes that allowed dogs to be excellent students of human social cues. For example, in an article published in the journal Animal Cognition, researchers found that dogs showed a stronger response to humans who were crying versus those who were simply talking or humming. This was true whether the subject was the dog’s owner or a stranger, indicating a high level of emotional aptitude when it comes to understanding people. Other studies found that, when interacting with each other, both humans and dogs experience a rise in the feel-good hormone oxytocin, which is released during positive social experiences such as hugging someone you love. Another study found that when dogs sniffed their owners’ scents, they formed a positive association through activation of the caudate nucleus, a reward center of the brain. These changes combined with canines’ natural need for a social group to help create the modern-day pets we call family. Group behavior is a survival mechanism for dogs, who rely on the success of their packs for their own survival and wellbeing. Many animal experts believe this pack mentality also applies to our pet’s relationship with their human family members. Packs survive because group members depend on each other and our pets bring this mentality into their modern-day social circles, contributing to the loyalty that dogs demonstrate when it comes to their beloved humans.