There's a new article out in Nature, looking at breastfeeding habits in the hominin species Austrolopithecus africanus. The researchers measured barium concentrations in fossilized teeth, which allowed them to estimate the importance of breastmilk in the diet across time. Nifty, right? They learned that A. africanus mothers nursed their babies exclusively for about 6-9 months, and then continued to offer breastmilk along with varying quantities of solid food for about 5 years.
So far so unsurprising, at least from my perspective as a hominin mother who is also a breastfeeding researcher and an IBCLC. These days hominin babies also get interested in solid food around the middle of their first year of life, and they often keep going for a while, augmented by varying quantities of solid food. This is old news. Anthropologist Kathy Dettwyler was publishing in the mid-90s on "normal" breastfeeding duration, and her work suggested that a natural age for weaning would range from 2.5, at the earliest, to about 7, at the latest. You can read a nutshell version of her work here, but the core idea is that we can learn from other species about the markers that indicate it's time to wean. For instance, some primates wean at the time of the emergence of the first permanent molars, which corresponds to an age of 5 or 6 in humans. Just like A. africanus!
(Standard disclaimer goes here: let's all do what works for our own families; let's also agree not to mutter darkly about the motivations of women who breastfeed for more or less time than we might find optimal.)
I was more than a little surprised, though, to see the investigator's take on these findings. Breastfeeding is metabolically costly, he says, and so perhaps the species died out BECAUSE the mothers kept nursing their children for so long.
Given what we know about primate nursing duration, this line of thinking suggests to me that the entire global population of primates ought to have died out in a mass extinction event some thousands of years ago. "Well, Pops," I imagine an early hominin mother saying to her grieving husband, "it was nice knowing you but I am PLUMB DONE IN by breastfeeding our offspring. And now I die." She keels over, like Wallace Shawn in The Princess Bride, while her overly breastfed 5-year-old continues to paw at her stiffening mammaries.
The researcher's comments tie in with a cultural narrative that breastfeeding is too draining, both literally and metaphorically, for women to manage. I first encountered this idea in college, when an older friend's father was telling her how much more rested she seemed when she gave the baby a bottle. I bumped up against it in person when I first nursed a toddler. "Oh, that must be very tiring," said a new acquaintance. (Awkwardly, she was my husband's boss's wife and she found it SO ODD for a 21-month-old to be nursing that her customary British reserve evaporated entirely.) The thing that's exhausting, though, is mothering a small child. Once you get past the initial bumps in the road, breastfeeding is more likely to be the shortcut than the hard road. (See the Swiss army knife analogy in this old post.)
You know who profits from pushing that breastfeeding-chews-you-up-and-spits-you-out business? Not mothers, not babies, not young children, but manufacturers of human milk substitutes and complementary foods. I am not aware of scholarly studies that support this idea of breastfeeding as health hazard -- not in human mothers from food-insecure populations, where the question can be of life-or-death import, and not in animal studies. Could it be that these were just normal primate mothers doing a normal primate thing? Could it be that pathologizing long-term breastfeeding -- though "pathologizing" seems an inadequate verb for "suggesting it is to blame for the extinction of an entire species" -- is a bad idea not grounded in actual science?
I told my kids they should keep an eye out to make sure I don't go extinct from breastfeeding.
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