When dogs bite
Most people accept without question that dogs live peacefully alongside humans. They sleep on our sofas, share our homes, play with our children, and interact with people and other dogs every day. Because of this long history of domestication, it is easy to forget one essential truth. It is deeply abnormal for a domestic dog to want to bite a human or another dog.
That does not mean biting cannot happen. It means that when it does, it is a serious red flag that something has gone very wrong, and the cause is rarely simple “bad behaviour.”
Domestication changed everything
Dogs have lived with humans for thousands of years. Their survival no longer depends on hunting, fighting off threats, or living independently. Research on domestication shows that dogs have been selected for reduced fear, increased sociability, and low aggression toward humans (Hare and Tomasello, 2005; MacLean et al., 2017).
Modern dogs cannot survive reliably on their own. They depend entirely on humans for food, protection, shelter, and medical care. They are genetically shaped to tolerate close human contact, routine handling, grooming, and even invasive procedures when appropriately introduced.
This means that a dog biting a person is not a normal survival behaviour. It is a sign of intense distress.
Tolerance is the baseline, not aggression
The average pet dog tolerates an incredible amount of daily stress. They tolerate children hugging them, people reaching over them, busy environments, uncomfortable equipment, and sometimes clumsy or inappropriate handling.
A dog does not simply choose to bite. Biting is the very last strategy in their communication toolbox. Before that come subtle signs: turning away, lip licking, freezing, paw lifting, yawning, or avoiding touch. When these early warnings are ignored or the dog is unable to escape, escalation can occur.
When a species that has been selected for non aggression shows aggression, it is a warning. Something is wrong.
There is strong scientific evidence that pain and medical problems are major underlying causes of aggression in dogs however we are quick to assume psychological problems, slow to assume pain
Human psychology is more familiar to us than canine physiology, so many owners default to imagining emotional or behavioural causes. The reality is that dogs rarely develop aggression without a physical trigger
If a dog bites a person, two things are almost always true:
1. The dog is terrified, often because early needs for safety, predictability, or humane handling were not met.
2. Or the dog is in pain, and pain has reduced their ability to cope.
In domestic dogs, aggression is not the norm. It is a symptom.