Postnatal foraging demands alter adrenocortical activity and psychosocial development

Area of Science:

• Primate behavior
• Developmental psychology
• Animal endocrinology

Background:

• Mother squirrel monkeys adjust infant carrying duration based on environmental demands.
• Food availability influences maternal care strategies and infant psychosocial development.

Purpose of the Study:

• To investigate how high-demand (HD) versus low-demand (LD) foraging conditions affect maternal care and infant development in squirrel monkeys.
• To characterize behavioral, adrenocortical, and social transaction changes during the transition from infant carrying to self-transport.

Main Methods:

• Collected behavioral, adrenocortical (cortisol), and social transaction data from 10- to 21-week-old squirrel monkey infants and mothers.
• Coded social interactions for initiator, goal (make/break contact), and outcome (success/failure).
• Compared HD and LD groups regarding maternal carrying, infant behavior, and cortisol levels.

Main Results:

• Mothers in HD conditions stopped carrying infants earlier than in LD conditions.
• HD infants initiated more make-contact attempts, often opposed by mothers, with low success rates.
• Cortisol levels were higher in HD mothers; infant cortisol differences were less consistent. Both groups spent similar time nursing and feeding on solids.

Conclusions:

• Squirrel monkey mothers reschedule infant carrying (carry to self-transport) in response to high food demand.
• This rescheduling may partially buffer infants from the immediate stress of difficult foraging.
• Developmental transitions are selectively modified by mothers to mitigate environmental challenges.