Of all human needs, companionship is the most important necessity for a happy, contented life. We are all social beings requiring interaction with other people at a variety of levels. We tend to perform better when placed in a group, rather than left alone. Our relationships address our different needs, be it social, emotional, physical or spiritual. Social isolation can lead to depression, and even cause diseases such as cancer, chronic pain or heart problems. Knowing that we have someone in this whole world to call upon, lean on, chat with or trust can help us live long, healthy lives.