Cortisol levels in bonobo infants jumped fivefold when they got a younger sibling and stayed high for 7 months, suggesting they found it extremely stressful
4 March 2022
Bonobo infants become highly stressed when they get a younger sibling and they don’t recover for seven months, according to a study that monitored levels of a stress marker in their urine.
In humans, many firstborn children struggle with the arrival of a sibling because “they’ve lived in a world where they have pretty unlimited access to parental time and attention, and now they’re having to share it”, says Matthew Sanders at the University of Queensland in Brisbane, Australia.
To explore whether …