TY - JOUR
T1 - Experience-independent sex differences in newborn macaques
T2 - Females are more social than males
AU - Simpson, Elizabeth A.
AU - Nicolini, Ylenia
AU - Shetler, Melissa
AU - Suomi, Stephen J.
AU - Ferrari, Pier F.
AU - Paukner, Annika
N1 - Funding Information:
This work was supported by the Division of Intramural Research, NICHD, and NICHD P01HD064653 (to PFF). We thank Timothy Mrozek for stimulus creation, Grace Maloney and Sheila Sutti for collecting eye tracking data, Michelle Miller, Anna Casey, Mandy Riddle, Ryan McNeil, Neal Marquez, and Kristen Byers for serving as the models for the human interaction test, Stefano Kaburu for caregiver interaction observations, and Kielee Jennings for data entry.
PY - 2016/1/22
Y1 - 2016/1/22
N2 - Human females exhibit greater social interest and skills relative to males, appearing in infancy, suggesting biological roots; however, male and female infants may be treated differently, potentially causing or amplifying sex differences. Here, we tested whether sex differences in social motivation emerge in infant monkeys (n = 48) reared in a controlled postnatal environment. Compared to males, females at 2-3 weeks looked more at conspecifics' faces (d = 0.65), especially the eyes (d = 1.09), and at 4-5 weeks exhibited more affiliative behaviors (d = 0.64), including gesturing, looking, and proximity to familiar and unfamiliar human caretakers. In sum, converging evidence from humans and monkeys suggests that female infants are more social than males in the first weeks of life, and that such differences may arise independent of postnatal experience. Individual differences in social interest have wide-ranging developmental consequences, impacting infants'social interaction quality and opportunities for learning. Understanding the evolution of sex differences and their developmental emergence is necessary to best support infants with varying levels of sociality.
AB - Human females exhibit greater social interest and skills relative to males, appearing in infancy, suggesting biological roots; however, male and female infants may be treated differently, potentially causing or amplifying sex differences. Here, we tested whether sex differences in social motivation emerge in infant monkeys (n = 48) reared in a controlled postnatal environment. Compared to males, females at 2-3 weeks looked more at conspecifics' faces (d = 0.65), especially the eyes (d = 1.09), and at 4-5 weeks exhibited more affiliative behaviors (d = 0.64), including gesturing, looking, and proximity to familiar and unfamiliar human caretakers. In sum, converging evidence from humans and monkeys suggests that female infants are more social than males in the first weeks of life, and that such differences may arise independent of postnatal experience. Individual differences in social interest have wide-ranging developmental consequences, impacting infants'social interaction quality and opportunities for learning. Understanding the evolution of sex differences and their developmental emergence is necessary to best support infants with varying levels of sociality.
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U2 - 10.1038/srep19669
DO - 10.1038/srep19669
M3 - Article
C2 - 26794858
AN - SCOPUS:84955466780
VL - 6
JO - Scientific Reports
JF - Scientific Reports
SN - 2045-2322
M1 - 19669
ER -