Breastfeeding durations in ancestral environments. A little extra something - part 3
A baby is an exterogestate foetus for at least the first nine months of life
Almost all cultures until modern times have breastfed until at least twenty-four months.
Even in our own society, it is widely impressed upon the mother that milk remains an essential food for children until at least two years of age.
The normative biological function of the human infant can be no more understood outside the context of breastfeeding than the foetus can be understood outside the context of the placenta. The immature immune system of the baby is a part of, or a satellite of, maternal immunity and of the entero-mammary and broncho-mammary lymphatic axes. The immature digestive system of the baby enjoys optimal host defence, microbial colonisation and enzymatic activity only in the context of breast milk. The immature endocrine system of the baby is complemented by and modulated by the hormones of breastmilk. The immature neurological system of the baby requires the irreplicable long-chained polyunsaturated fatty acids of breastmilk for optimal development.
Breastfeeding is the second (or ex-utero) stage of the gestation of the human being
Breastfeeding is the second stage of the gestation of the human being. Humans have an unusually prolonged juvenile dependence (especially compared with most mammals), and human milk is comparatively low in protein. Our baby is neurologically immature at the severance of the umbilical cord, an exterogestate foetus, nourished and protected by the breasts of the mother and body of other carers into physiological autonomy.
When a breastfeeding toddler takes milk from his mother's breasts, he receives a good dose of immune medicine for his little body. The milk has become at this stage richer than ever in fats and antibodies, in lactoferrin and lysozyme. It is a glassful of health insurance, a glassful of important micro-nutrients and essential fatty acids. Research verifies health advantages of prolonged breastfeeding.
The WHO/UNICEF Innocenti Declaration, visioning for global health of the child, states that children should continue to be breastfed, while receiving appropriate and adequate complimentary foods, for up to two years of age or beyond.
2025 note:
"Continuation of breastfeeding past the exclusive breastfeeding period may facilitate developmental programming that could potentially reduce risk of obesity and non-communicable disease later in life. Differences in protein intake between breastfed and formula fed infants during first 12 months is attributed to lower intake of protein from human milk, not to a difference in protein intake from solid foods." Gridneva et al 2018 Nutrients
I wrote the essay A little extra something when I lived in Bullaburra, in the Blue Mountains. My children were very young. It took me a good six months and I thought about it day and night. I wrote it in response to Wyeth's advertisements for commercial milk formulas which were appearing regularly across a range of medical journals and in the medical news at that time. As a GP, I couldn't escape these ads: they were everywhere in the professional materials I accessed. In every spare moment, when my children were asleep or in someone else’s care, I sat in my cramped study overlooking the wild green Bullaburra gully with its raucous flocks of sulphur-crested cockatoos, dreaming and writing, writing and dreaming, urgently. ...Then when I finished it in August 1994, I didn’t publish it. I had no idea who might be interested. I’ll never forget that Maureen Minchin kindly read every word and told me down the phone that she really liked it. After we hung up, I shouted out with happiness into the bright gully air. This is an updated excerpt.
Recommended resources
White blood. A little extra something - part 2
Mamma, mother: the Earth is crying. A little extra something - part 5
Selected references
Gridneva Z, Tie WJ, Rea A, Lai CT, Ward LC, Murray K, Hartmann PE, Geddes DT. Human milk casein and whey protein and infant body composition over the first 12 months of lactation. Nutrients. 2018 Sep 19;10(9):1332. doi: 10.3390/nu10091332. PMID: 30235880; PMCID: PMC6164442.
Ramiro-Cortijo D, Singh P, Liu Y, Medina-Morales E, Yakah W, Freedman SD, Martin CR. Breast milk lipids and fatty acids in regulating neonatal intestinal development and protecting against intestinal injury. Nutrients. 2020 Feb 19;12(2):534. doi: 10.3390/nu12020534.
Veille A, Miller V. Duration of breast feeding in ancestral environments. In: Shackelford TK, Weekes-Shackelford VA, editors. Encyclopedia of Evolutionary Psychological Science. https://doi.org/10.1007/978-3-319-19650-3_818