Humans and dogs have shared an inseparable bond that dates back well over 15,000 years. Throughout the ages our constant companions offered unconditional love and friendship, and now new research shows they empathize with us.
Dogs have played a pivotal role in human history. They have acted as draft animals, assisted with hunting and herding, offered both warmth and protection, guided the blind and they have humored us with play.
The first evidence of dogs and humans being buried together comes from a German site 'Bonn-Oberkassel' about 14,000 years ago. Also around that period dogs followed humans across the Bering Land Bridge into North America. The first evidence of human and dog internment was recorded at Danger Cave, Utah some 11,000 years ago.
It now turns out that people and dogs are linked very closely from behavioral patterns associated with a simple yawn.
When humans yawn, scientists believe it's an indicator of tiredness, stress and overwork. Yawning may help to cool off the brain and it's often followed by the urge to stretch.
Many animal species yawn -- from house cats to lions and jaguars and from horses to owls and many others. In the wild kingdom contagious yawning, however, has only been recorded within three species: gelada baboons, stump-tailed macaques and chimpanzees. Until recently no animal that scientists were aware of crossed the species barrier with contagious yawning.
In 2007, workers from the University of Leeds found that contagious yawning indicated empathy and appreciation of people's behavior and psychological state.
Research from the University of Porto in Portugal just found that dogs yawned five times more often when they heard recordings of humans they knew yawning as opposed to an unfamiliar person.
This remarkable discovery shows that dogs crossed the species barrier by 'catching a yawn' and exhibiting contagious behavior. It also shows that dogs have a capacity to empathize with humans, or more specifically, their respective owner's.
So the next time you come home after a long, tough day and your canine best friend wags his tail offering boat-loads of unconditional love -- know that he understands more than you may realize.
Earth Dr. Reese Halter is an award-winning broadcaster and distinguished biologist. His latest books are: The Incomparable Honeybee and The Insatiable Bark Beetle.