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2021 Abstracts

Rhesus Monkey Strain Type and Mother-Infant Relationship

Presenters: Roger Woods, Family, Home, and Social Sciences, Psychology
Authors: Roger Woods, Lindsey Edwards, Jacob Hunter, Zachary Baron, Stephen Lindell, Stephen Suomi, J. Dee Higley
Faculty Advisor: J. Dee Higley, Family, Home, and Social Sciences, Psychology
Institution: Brigham Young University

Rhesus monkeys are the most studied of all nonhuman primates, and are composed of two main strains, the Chinese-derived rhesus macaque, which needed to cross unpredictable and perilous territories to attain its current geographic distribution, and the Indian-derived rhesus macaque, which followed a more resource-abundant path. A handful of studies have examined behavioral differences between the two groups, but no studies have previously assessed how the mother-infant bond in these two strains may have adapted to suit their environmental conditions, or the effect of this relationship on infant behavioral development. The present study compares mother-infant behaviors that characterize the quality of this relationship, and infants’ behaviors with their social and environmental surroundings over the first four months of life in groups of Chinese-derived infants being raised by Chinese (n=13) or Indian-derived mothers (n=21), as well as Indian-derived infants being raised by Chinese (n=7) or Indian-derived mothers (n=140). Regardless of infant strain, Chinese-derived mothers spent less time cradling their infants. Perhaps as a consequence, when both groups of infants were raised by a Chinese-derived mother, Chinese-derived infants spent less time being active and exploring their environments compared to Indian-derived infants, but no differences in these behaviors were discovered between infants of either strain when reared by Indian-derived mothers. The results suggest that Chinese-derived mothers are less involved in infant care, and exhibit reduced function as a secure base for the infant to engage with their surroundings when offspring are Chinese-derived. It is possible that this variation in maternal style and infant response may be part of an evolutionarily conserved mechanism that adaptively lowered the risk of infant injury or death in the perilous environments Chinese-derived rhesus monkeys came to occupy.