Purely coincidental that this is Episode 013 and the title is “Fear Helps You Grow”.
In a 2004 study, the psychologist Karen Parker set out to explore the effects of early exposure to fear in squirrel monkeys.
A group of 17-week-old monkeys were taken from their mothers and placed in a cage with other adult monkeys, previously unknown to them, for one hour. They were then returned to their mothers. This procedure was repeated once a week for a period of ten weeks.
The results were fascinating.