Boys and Girls may get different breast milk

http://www.scientificamerican.com/article.cfm?id=boys-and-girls-may-get-different-breast-milk

by crassus • 13 years ago

77 52 13 years ago

drpgq• 13 years ago

How does the mother's body know the sex of the child? Is it detected somehow during the pregnancy and if so where is this information kept?

tantalor• 13 years ago

Male fetal DNA is found in the brains of mothers.

http://www.latimes.com/health/boostershots/la-heb-women-brai...

seiji• 13 years ago

Bluetooth LE / iBeacons

jurjenh• 13 years ago

I could imagine some sort of organ senses - child has certain hormones (eg testosterone) in salive, and certain receptors on the nipple pick up on these hormones and then tailor the milk.

Note that I have no basis for this claim, but one of the many ways the body communicates is through hormones, so it certainly wouldn't be outside the realms of possibility...

timini• 13 years ago

What about twins?

mooism2• 13 years ago

What if the mother is feeding a pair of non-identical twins (a boy and a girl)?

AmVess• 13 years ago

One discrete tit for each tot? Beyond that, who knows. I'd love to see this phrase turn up in an academic journal somewhere.

jacalata3• 13 years ago

But they don't do that.

gmuslera• 13 years ago

Is not just "food" what is passed with breast milk, also beneficial bacterias http://www.sciencedaily.com/releases/2012/04/120429234641.ht... Not sure how that regulates itself regarding sex, age or health of the child, but seems that it happens.

brosco453• 13 years ago

Also, immunogoblins and other stuff we do not know.

cup• 13 years ago

It raises the question not just about twins but also about wet nurses. I mean its a pretty normal tradition for mothers to 'outsource' their breast feeding to other mothers, especially if they're tired or sick.

Also what about formula milk?

brosco453• 13 years ago

Breast milk is the best choice.

jacalata3• 13 years ago

That was not the question, and even people who accept that should understand that breast milk is not always an option, for instance for the father I know whose wife died shortly after they had a child.

rayiner4• 13 years ago

What about formula milk? The long term benefits of breast feeding are so tenuous that I can't imagine there's a practical significance to the difference between breast milk produced for girls versus boys in human babies: http://www.skepticalob.com/2013/05/world-health-organization....

Studies like these are valuable, but it's tempting to jump from interesting observation to policy recommendation without keeping in perspective (or even bothering to quantify) the magnitude of the impact.

An excellent blog post on the state of research into breast feeding: http://www.skepticalob.com/2013/06/two-crappy-new-breastfeed...

maratd2• 13 years ago

The long term benefits of breast feeding are so tenuous

This is a joke, right?

Simple reasoning and deduction will lead you to the right answer. We evolved to drink the milk of our mothers, not a chemical concoction derived from the milk of cows fed by corn.

dingaling• 13 years ago

The long-term benefits may be tenuous or as-yet undetermined, but the short-term benefits are so overwhelming that the WHO paper to which you link states quite clearly, citing the WHO Global strategy for infant and young child feeding:

Given such evidence, it has been recommended that in the first six months of life, every child should be exclusively breastfed, with partial breastfeeding continued until two years of age.

That's WHO guidance. They don't broker much consideration for formula milk in that statement.

kimonos• 13 years ago

Wow! Great info!

haversine• 13 years ago

"These findings could have implications for formula, which could be tweaked to optimize development for both boys and girls."

As the father of a little girl, I find this sentence more ominous than was probably intended. The formula aisle is already overly complex with Regular, Iron Enriched, Omega Enriched, Soy, Low-Lactose, and No Lactose, among the many yogurt sounding ones (pre/macro/post/whatever-biotic).

However, I am worried (perhaps due to cynicism) that instead of rationally simplifying this system, it might be dumbed down to Boy and Girl formula. Though I guess there may be benefits as well. sigh - glad I'll probably be done having kids by then :D

jonah• 13 years ago

Keep away from the formula aisle if at all possible!

nappy-doo• 13 years ago

I have nothing constructive to say about the article, but for the record: gender is chosen, sex is not. I wish the world would get this right, especially Scientific American, which got it wrong in the second sentence.

Here's an interesting link: https://books.google.com/ngrams/graph?content=gender%2C+sex&...

crazygringo• 13 years ago

The world doesn't seem to agree with you. Straight from Wikipedia [1]:

Gender is the range of physical, biological, mental and behavioral characteristics pertaining to, and differentiating between, masculinity and femininity. Depending on the context, the term may refer to biological sex (i.e. the state of being male, female or intersex), sex-based social structures (including gender roles and other social roles), or gender identity. ... the meaning of gender has undergone a usage shift to include sex or even to replace the latter word. .... Gender is now commonly used even to refer to the physiology of non-human animals, without any implication of social gender roles.

[1] http://en.wikipedia.org/wiki/Gender

LesZedCB• 13 years ago

From the same article:

The modern academic sense of the word, in the context of social roles of men and women, dates from the work of John Money (1955), and was popularized and developed by the feminist movement from the 1970s onwards (see Feminism theory and gender studies below). The theory was that human nature is essentially epicene and social distinctions based on sex are arbitrarily constructed. Matters pertaining to this theoretical process of social construction were labelled matters of gender.

I think most places people hear it is that gender is the male/female/other self-description, and sex is the physiological state.

ebfe• 13 years ago

I think you're confusing the sociological/social justice definition of gender with the literal one. In the case of the latter, sex and gender are synonymous.

TazeTSchnitzel2• 13 years ago

You beat me to it. Gender is not sex.

gweinberg• 13 years ago

If this result is valid, it's probably also true for other mammals that bear young one at a time. If so, it's proabably a lot easier to verify in cows than humans. Less paperwork required for experiments, for one thing.

vwinsyee• 13 years ago

From the article: "These findings, published in the American Journal of Physical Anthropology in September, echo previous work that showed milk composition varying with infant gender in gray seals and red deer and with infant gender and the mother's condition in rhesus macaques."

TazeTSchnitzel2• 13 years ago

researchers have found that milk composition changes depending on the infant's gender

Sex. Infant's sex. Gender is rarely known at that stage.

Nursie2• 13 years ago

Will the patriarchy stop at nothing to keep women down?!

ohwp• 13 years ago

Why do you think this article is about keeping women down?

Nursie2• 13 years ago

I don't. I was being flippant.

hellrich• 13 years ago

Sarcasm?

grandinj• 13 years ago

Well duh. All babys get different breast milk. There is a feedback loop between the child and the mother that modifies the milk on an ongoing basis.

jacalata3• 13 years ago

I've never heard anything like that, odd they don't mention it in the article. Got any intro-level references? How does it work?

beat• 13 years ago

My wife breastfed our boy/girl twins. I wonder where that fits in?

nicholas73• 13 years ago

I don't think the mechanism is a direct biological signaling of the baby's sex to tell the woman to produce fattier milk. It seems more plausible to me that wealthier families value boys a lot more - you see this tendency everywhere. This causes mothers to value their male children disproportionately, and the social feedback she gets probably affects her hormones as well, which would cause the milk to vary. So you see the large difference in wealthier women's milk for boys and girls, whereas the difference in poorer women's milk may not even be statistically significant.

I think if you repeat this test on different circumstances where the child is valued or not, whether boy or girl, you will find similar results that remove the sex factor.

wutbrodo• 13 years ago

Surely the cultural explanation doesn't extend to similar behavior found in grey seals, red deer, and rhesus macaques? Convergent evolution is always a possibility but it seems like the likelihood lies with a biological explanation vs a cultural one.

1humanwoman• 13 years ago

I posted on this story and the issues it raises here: http://humanwithuterus.wordpress.com/2013/12/18/gendered-bre...

Would love your thoughts!

Boys and Girls may get different breast milk

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