In poor families, mothers' milk is richer for daughters than sons: A test of Trivers–Willard hypothesis in agropastoral settlements in Northern Kenya

Fujita, Masako; Roth, Eric Abella; Lo, Yun Jia; Hurst, Carolyn; Vollner, Jennifer; Kendell, Ashley

doi:10.1002/ajpa.22092

Cited by 116 publications

(101 citation statements)

References 58 publications

(106 reference statements)

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“…This relationship has been demonstrated in many species, including humans (Homo sapiens, Powe et al, 2010;Fujita et al, 2012), rhesus macaques (Macaca mulatta, Hinde, 2007aHinde, , 2009) red deer (Cervus elaphus hispanicus, Landete-Castillejos et al, 2005), and tammar wallabies (Macropus eugenii, Robert and Braun, 2012). A common trend in these studies is that milk composition, particularly fat, protein and/or energy density, tends to be higher in the milk of mothers nursing sons than in mothers nursing daughters.…”

Section: Maternal Characteristics and Milk Compositionmentioning

confidence: 90%

Milk matters: offspring survival in Columbian ground squirrels is affected by nutrient composition of mother's milk

Skibiel

Hood

2015

Front. Ecol. Evol.

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Through maternal effects, information about environmental conditions experienced in the maternal generation can be transmitted to subsequent generations. Although maternal effects have been described and quantified in many mammalian species, the underlying causal links are often under-studied. The close association between mother and neonate during the extended period of lactation in mammals provides a unique opportunity for mothers to influence offspring phenotype through nutrient provisioning of milk. The purpose of this study was to examine sources of inter-individual variation in milk composition and impacts on offspring phenotype and survival. Variation in fat content, protein content, and energy density of mother's milk was associated with timing of reproduction. Mothers with intermediate birthdates produced milk that was higher in fat and energy density, but lower in protein than females with early or late birthdates. In turn, the pattern of change in milk composition affected juvenile overwinter survival. The protein content of Columbian ground squirrel milk typically increases to peak lactation and then declines before weaning. Pups consuming milk that was lower in protein in early lactation but then relatively high in protein at peak and late lactation had a higher probability of survival overwinter. Our results indicate that the interplay between the timing of reproduction and lactation performance has consequences for maternal and offspring fitness.

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Section: Maternal Characteristics and Milk Compositionmentioning

confidence: 90%

Milk matters: offspring survival in Columbian ground squirrels is affected by nutrient composition of mother's milk

Skibiel

Hood

2015

Front. Ecol. Evol.

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“…Recently, Powe et al (2010) and Fujita et al (2012) have reported preliminary evidence for sex-based differences in human milk composition-particularly fat and energy. However, several large prior studies of human milk have not reported differences in the milk composition of mothers nursing male or female infants (Prentice et al, 1981;Nommsen et al, 1991;Mitoulas et al, 2002), either reflecting a lack of findings or investigation.…”

Section: Introductionmentioning

confidence: 98%

No evidence for sex biases in milk macronutrients, energy, or breastfeeding frequency in a sample of filipino mothers

Quinn

2013

American J Phys Anthropol

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Maternal reproductive investment includes both the energetic costs of gestation and lactation. For most humans, the metabolic costs of lactation will exceed those of gestation. Mothers must balance reproductive investment in any single offspring against future reproductive potential. Among mammals broadly, mothers may differentially invest in offspring based on sex and maternal condition provided such differences investment influence future offspring reproductive success. For humans, there has been considerable debate if there are physiological differences in maternal investment by offspring sex. Two recent studies have suggested that milk composition differs by infant sex, with male infants receiving milk containing higher fat and energy; prior human studies have not reported sex-based differences in milk composition. This study investigates offspring sex-based differences in milk macronutrients, milk energy, and nursing frequency (per 24 h) in a sample of 103 Filipino mothers nursing infants less than 18 months of age. We found no differences in milk composition by infant sex. There were no significant differences in milk composition of mothers nursing first-born versus later-born sons or daughters or between high- and low-income mothers nursing daughters or sons. Nursing frequency also showed no significant differences by offspring sex, sex by birth order, or sex by maternal economic status. In the Cebu sample, there is no support for sex-based differences in reproductive investment during lactation as indexed by milk composition or nursing frequency. Further investigation in other populations is necessary to evaluate the potential for sex-based differences in milk composition among humans.

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“…Suckling behavior, however, is not useful for estimating milk energy transfer as verified by experimental use of radio-labeled isotopes in Equus caballus [22]. Direct evidence for sex-biased milk synthesis among nondomesticated species has now been reported in ungulates (Cervus elaphus hispanicus, [23]), rodents (Myodes glareolus [24]), primates (Macaca mulatta [25][26]; Homo sapiens [27][28][29], but see also [30] for exception), and marsupials (Macropus eugenii, [31]). Drawing systematic conclusions from the studies to date, however, is challenging in part because most have been limited by relatively small sample sizes or report milk composition without accounting for milk yield.…”

Section: Introductionmentioning

confidence: 99%

Holsteins Favor Heifers, Not Bulls: Biased Milk Production Programmed during Pregnancy as a Function of Fetal Sex

Hinde

Carpenter

Clay

et al. 2014

Preprint

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Mammalian females pay high energetic costs for reproduction, the greatest of which is imposed by lactation. The synthesis of milk requires, in part, the mobilization of bodily reserves to nourish developing young. Numerous hypotheses have been advanced to predict how mothers will differentially invest in sons and daughters, however few studies have addressed sexbiased milk synthesis. Here we leverage the dairy cow model to investigate such phenomena. Using 2.39 million lactation records from 1.49 million dairy cows, we demonstrate that the sex of the fetus influences the capacity of the mammary gland to synthesize milk during lactation. Cows favor daughters, producing significantly more milk for daughters than for sons across lactation. Using a sub-sample of this dataset (N = 113,750 subjects) we further demonstrate that the effects of fetal sex interact dynamically across parities, whereby the sex of the fetus being gestated can enhance or diminish the production of milk during an established lactation. Moreover the sex of the fetus gestated on the first parity has persistent consequences for milk synthesis on the subsequent parity. Specifically, gestation of a daughter on the first parity increases milk production by ,445 kg over the first two lactations. Our results identify a dramatic and sustained programming of mammary function by offspring in utero. Nutritional and endocrine conditions in utero are known to have pronounced and long-term effects on progeny, but the ways in which the progeny has sustained physiological effects on the dam have received little attention to date.

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In poor families, mothers' milk is richer for daughters than sons: A test of Trivers–Willard hypothesis in agropastoral settlements in Northern Kenya

Cited by 116 publications

References 58 publications

Milk matters: offspring survival in Columbian ground squirrels is affected by nutrient composition of mother's milk

Milk matters: offspring survival in Columbian ground squirrels is affected by nutrient composition of mother's milk

No evidence for sex biases in milk macronutrients, energy, or breastfeeding frequency in a sample of filipino mothers

Holsteins Favor Heifers, Not Bulls: Biased Milk Production Programmed during Pregnancy as a Function of Fetal Sex

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