For thousands of years, humans have dreamed of finding the secrets to long life, even immortality. Until now, the dream has been elusive. But scientists and doctors are beginning to understand the fundamental mechanisms that cause the human body to grow, and to deteriorate. Will we one day clone ourselves? Or will we simply inject ourselves with hormones that keep us permanently spry? CBS News 48 Hours takes a look at some modern attempts to sidestep death. Some will amaze you, others may cause you to scratch your head in wonder.