This is excerpted from TIME How Dogs Think: Inside the Canine Mind.
You speak dog better than you think you do. You may not be fluent; that would require actually being a dog. But if you went to live in a dogs-only world, you’d be pretty good at understanding what they’re saying. You can tell a nervous yip from a menacing growl, a bark that says hello from a bark that says get lost. You can read the body language that says happy, that says sad, that says tired, that says scared, that says Please, please, please play with me right now!
Think that’s not a big deal? Then answer this: What does a happy bird look like? A sad lion? You don’t know, but dog talk you get. And as with your first human language, you didn’t even have to try to learn it. You grew up in a world in which dogs are everywhere and simply came to understand them.
That, by itself, says something about the bond that humans and dogs share. We live with cats, we work with horses, we hire cows for their milk and chickens for their eggs and pay them with food—unless we kill them and eat them instead. Our lives are entangled with those of other species, but we could disentangle if we wanted.