Stress inoculation, such as separating infant monkeys from their mothers for short periods, can lead to better stress handling and reduced cortisol response later in life.

“There are studies, Karen Parker at Stanford has done some wonderful studies with primates about stress inoculation. That if you separate a baby monkey from his mother for two hours a day and then reunite them, and then you stress that baby monkey later, they actually handle stress better. There's less cortisol arousal in the face of distress, stress inoculation, that's been called.”