KEYNOTE: Boy Milk & Girl Milk: Evolutionary Insights

Katie Hinde, Human Evolutionary Biology, Harvard University, Cambridge, Massachusetts

Abstract only.  For more information, please contact Dr. Hinde at: katiehinde@gmail.com

Among mammals, mother’s milk provides structural materials and hormonal signals necessary for infant development. Where the ontogenetic priorities diverge between sons and daughters, from either the mother’s or the infant’s perspective, sex-differentiated milk synthesis or milk assimilation may emerge. In recent years sex-differentiated milk synthesis has been reported in numerous mammals including ungulates, primates, rodents, and marsupials. Differences in milk macro-constituents, minerals, hormones, and volume may favor of sons or daughters depending on their developmental needs or their future reproductive potential. Experimental research has demonstrated that both prenatal and post-natal factors contribute to the production of sex-differentiated milk. Additional evidence suggests that even when mothers seemingly produce identical milk for sons and daughters, the utilization and assimilation of milk constituents differs between the sexes. Here I will discuss mechanistic pathways, physiological constraints, and life-history trade-offs that likely influenced the presence and magnitude of sex-biased milk. Understanding these aspects of milk can enhance human health in many ways, including the adoption of matched donor milk and refinement of commercial formulas. In these ways an evolutionary perspective importantly contributes to discussions within clinical practice, public health, and dairy science.

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