The "placebo effect": a strange phenomenon wherein patients are healed without drugs, often ascribed to someone else simply taking an interest in our well-being. It is why psychotherapy, homeopathy, and other alternatives treatments have been so successful. But where does it come from? Is it unique to humans? Other factors, rarely discussed, have a strong influence on our health, such as: education, social class, dietary habits, social group. Being surrounded by friends and family, or having a pet can significantly extend life expectancy. This book reveals the deep connections between our health and our relationships.