An overlooked organ may a master switch to a longer, healthier life. While every organ in the human body has a purpose, some serve theirs for only a short time — or so we previously thought. Now, new research has found that the health of one in particular not only indicates a longer life, but could also be instrumental in fighting off cancer and other deadly illnesses. For years, there was a widely held belief that our thymus gland — the bowtie-shaped organ located in the upper chest — become