It's undeniable the bond that we share with our furry best friends. But why are we so inseparable? Humans domesticated dogs over 14,000 years ago. The relationship began as a mutual service agreement. Dogs offered protection while humans offered food. Because humans and dogs spent so many years evolving together, that bond gradually became more affectionate. Petting a dog has been shown to decrease stress levels. Dogs and people can even understand each others' languages. Today, the average dog-owner spends over $2,000 per year on food, toys and veterinary care. But the love that dogs give us is truly priceless.