Breast milk is weirder than you think

If you think about lactation too hard, it starts to seem a little strange — like the biological equivalent of saying the word "that" over and over until it's just a weird sound you're making. But, writes Nicholas Day at Slate, the sort of existential weirdness of breast milk is nothing compared to what's going on in the stuff at a chemical level. For instance, breast milk contains sugars that aren't actually digestible by human infants. That's because they aren't meant for the infant, itself. Rather, your breast milk is helpfully feeding your baby's intestinal bacteria. Freakier still: In monkeys, the chemical composition of breast milk can change, depending on factors like your baby's sex and whether your baby is showing signs of illness.

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  1. I don’t see what’s freaky and weird here.  Biology.  Evolution.  Titty milk made my son strong and healthy.

  2. This may be relevant to some proposals to try to re-create extinct animals from their DNA. A living thing is an ecosystem; from insects to humans, we rely on a huge number of symbiotic creatures with completely different DNA.  If termites somehow went extinct, and we cloned new ones from their DNA, they would starve: they eat wood but rely on organisms in their guts to digest the wood.  Babies need their gut bacteria. Maybe neanderthals had different gut bacteria.

    1. Probably depends on how different the species is from modern-day relatives. I suspect a baby mammoth could probably survive with the milk and bacteria from a surrogate mother elephant.

  3. Cool.  This should throw a bone to the creationistas,  I love the complexity of biology.

  4. Also awesome: if the baby has an eye infection, you can squirt some milk into their eye straight from the jugs. 

  5.  So, just thinking out loud here . . .  there are sugars (oligosaccharides, simple sugars) in human milk that humans don’t digest. Many vegans argue that we shouldn’t drink cow’s milk because there are sugars (disaccharides, simple sugars) that we can’t digest in it.
    Is it possible that the cow’s milk elements that we can’t digest have some other functions as well, even in the cow? Or that these sugars are similar?
    Interesting stuff!

  6. That’s right, TITTY milk evolved and makes SONS stronger rawr…or not…perhaps it’s the JUG spraying?

  7. Think of this the next time some formula company touts the latest and greatest micronutrient that they have added to their recipe in order to make it closer to breast milk. Nothing can compete with breast milk for infant nutrition–nothing. And even if you could simulate breast milk to a tee, you couldn’t emulate the way that it changes dynamically in response to the infant’s needs.

    There is a time and place for formula, but no one should dispute that it is nutritionally inferior to breast milk.

  8. There’s all sorts of food that our microbiome helps us digest, so I’m not sure breast milk is particularly unusual in that respect – and since we don’t function at all well without that bacteria present, it seems increasingly obvious that those colonies *are* as much “me” or “you” as (say) a red blood cell is.

    1. It’s the Windex of bodily fluids.

      (Yes, I just made a reference to a romantic comedy. So shoot me.)

  9. In monkeys, the chemical composition of breast milk can change, depending on factors like your baby’s sex and whether your baby is showing signs of illness.

    C’mon, the real story here is the diagnostic powers of these prescient monkeys.

    1. …the chemical composition of breast milk can change, depending on factors like your baby’s sex and whether your baby is showing signs of illness.

      I bet my wife’s boobs got mightily confused when they were producing milk for our boy/girl twins.

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