Daughter dearest: Sex-biased calcium in mother's milk among rhesus macaques

• Published in: American journal of physical anthropology 2013-05, Vol.151 (1), p.144-150
• Main Authors: Hinde, Katie, Foster, Alison B., Landis, Lauren M., Rendina, Danielle, Oftedal, Olav T., Power, Michael L.
• Format: Article
• Language: English
• Subjects: Animals; Anthropometry; Calcium - analysis; Calcium - metabolism; Caseins - analysis; Caseins - metabolism; Diet; Female; infant skeletal development; Infants; lactation; Lactation - physiology; life history; Macaca mulatta - growth & development; Macaca mulatta - metabolism; Macaca mulatta - physiology; maternal investment; Milk; Milk - chemistry; Milk - metabolism; Milk Proteins - analysis; Milk Proteins - metabolism; Mothers; nutrition; Old World monkeys; Phosphorus - analysis; Phosphorus - metabolism; Physical anthropology; Regression Analysis; Sex differentiation; Sex Factors
• ISSN: 0002-9483; 1096-8644; 2692-7691
• DOI: 10.1002/ajpa.22229

ABSTRACT Mother's milk provides building blocks necessary for infant development and growth postnatally. Minerals in milk are particularly important for infant skeletal development and may reflect maternal characteristics that are associated with the capacity to synthesize milk and sex‐specific developmental priorities of the infant. Using a large sample of mother–infant dyads assigned to the outdoor breeding colony at the California National Primate Research Center (N=104), we investigated the relationship of milk calcium (Ca) and phosphorus (P) concentrations and the ratio of Ca/P to maternal and infant characteristics and to other milk variables. Ca and P are largely associated with casein micelles, and as expected, both Ca and P were positively correlated with protein concentrations in milk. Neither Ca nor P concentrations were associated with maternal parity. Mothers rearing daughters tended to produce higher mean Ca concentration in milk, and consequently a higher Ca/P ratio, than did mothers rearing sons, even though protein concentration was not elevated. These results suggest that the Ca/P ratio in rhesus milk may have been under separate selective pressure from protein content to facilitate the accelerated rate of skeletal calcification that has been observed in female Macaca mulatta infants. Am J Phys Anthropol 151:144–150, 2013. © 2013 Wiley Periodicals, Inc.