Final answer:
Carson's findings involve the ancient practice of trephination and the belief that it cured mental illnesses by allowing evil spirits to escape, as well as insights into phrenology, a discredited pseudoscience.
Step-by-step explanation:
The technique Carson found for placing metal rings on the back and front of the skull is related to trephination, an ancient practice which involved making holes in the skull. This procedure was believed to allow evil spirits to leave the body, potentially curing mental illness and other disorders. Various artifacts, like the Jericho Skull found in 1953, give insights into ancient practices involving skulls. CT scanning and 3D printing have since provided deeper understanding of the individuals to whom these skulls belonged. Another historical concept involving the skull is phrenology, a pseudoscience proposed by Franz Gall in the 18th century, which suggested that one's personality traits could be determined by the shape of their skull. This has long since been discredited. Such historical insights into skull-related practices underscore our ancestors' fascination with this aspect of human anatomy.