neural implant called a "jewel"—a small computer inserted into the brain at birth that monitors its activity in order to learn how to mimic its behavior. By the time one reaches adulthood, the jewel's simulation is a near-perfect predictor of the brain's activity, and the jewel is given control of the person's body while the redundant brain is discarded. In this way, people with the jewel can eliminate the cognitive decline associated with aging by implementing their minds on a machine. Also, by transplanting the jewels into cloned bodies genetically altered to develop without brains, they can live youthfully forever.