Petrie Dish: The lonely body

Loneliness doesn't just feel bad. It appears to raise the risk of heart disease, dementia, and early death. In part one of a two-part Petrie Dish series on the loneliness crisis, Bonnie Petrie talks to a researcher separating marmoset monkeys from their mates to study the body's stress response, and a psychiatrist mapping what isolation does to the human brain.