An additional explanation for the health benefits derived from dogs has been studied experimentally. This theory holds that pets, including dogs, have a direct physiological effect on humans. In a pilot experiment, the blood pressure of adults stroking and talking to pet dogs was measured and proved to be no different from when they were resting quietly alone, and it might even fall in the presence of the dog. This contrasts strongly with what happens when people engage in l1uman conversations, when blood pressure almost always rises in separate study, the mere presence of a pet dog in a room was found to cause a lowering in blood pressure of children aged between nine and sixteen years.
The mechanism by which the stress reduction might work is still unclear and may have several components: the soft coat of a dog is pleasant to stroke, and warmth, people often stroke their dogs almost without being aware of it, something which has been termed the 'idle touch', very different from people The only child often treats the dog as the longed-for sister or brother, developing in this way a protective instinct towards smaller and helpless beings For the older person on his Own, the trusting companion often constitutes the most compelling reason for a continued, orderly existence consciously touching each other. The effect appears to be reciprocal since the blood pressure of the dog is known to fall when it is being stroked.lt has further been suggested that the presence of calm animals, unconcerned with a n y dangers from their environment, has been a sign for relaxation and safety to man for most if not all of his evolutionary history. Set in a modern-home context, the sight of a contented dog may fulfill the same role and explain why a dog can reduce stress and make people feel secure.