Do human females produce more milk (relatively to average child weight weight) than other primate females? Are human females more likely to feed several children through breastfeeding than other primates?

P.S. I am asking this, because it's what my antropologic hypothesis predicts: some women refused to nurse (and breastfeed) children born by them, so "nurses" - other women - fed those children. This, of course, would require those women to have extra (more than needed to feed their own children) amount of milk.

  • $\begingroup$ It seems certain. 1)There are twins fed by a single mother. 2)There were mothers who suckled a second child for payment. 3)The suckling period of an infant can be long and suckling of multiple babies can occur. But as the milk is adapted to the baby, the first one, if old enough, often stops, because the flavour changes. At least that’s what mothers say. $\endgroup$ – Ludi Jul 11 '18 at 11:34
  • $\begingroup$ @Ludi, seems reasonable and p. 1. is what I already had in mind. However this is not scientific approach, of course. I'm pretty sure other species also can have twins. $\endgroup$ – rus9384 Jul 11 '18 at 11:50
  • $\begingroup$ I disagree with the close voter that this question has anything to do with personal health. I do think the question could be improved, however. The word "excessively" doesn't help you here, it doesn't seem to be what you are actually asking. What you are actually asking is "Is it typical for a primate mother to produce enough milk to feed more than her own offspring?" I think an edit like that would improve the reception of your question, and you can copy my wording if you'd like but I prefer not to make major edits to peoples' questions without their agreement. $\endgroup$ – Bryan Krause Jul 11 '18 at 17:31
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    $\begingroup$ Milk production (in all mammals, as far as I'm aware) is stimulated by suckling, and is limited by the health of the lactating individual, not the number of offspring produced. Provided they let you, you can milk a cow, goat, mouse, marmoset... I would speculate that wet-nurse behavior is more about the social behavior of a species than the maximum milk producing capacity. $\endgroup$ – De Novo Jul 11 '18 at 22:34
  • $\begingroup$ @DanHall, I don't say it's limited by the number of offsprings produced. Won't you argue cows (especially on farms) have excessive milk? I'm rather asking if that's limit is higher in humans. $\endgroup$ – rus9384 Jul 11 '18 at 22:37

The comparison to non-human primates and the behavioral question kind of threw me, but I think this is an X-Y problem. If you're asking:

Are humans capable of producing more milk than they need to feed their own offspring

The answer is yes

There is some data I don't think we'd be able to get anymore, but in Chapter 5 of Nutrition During Lactation, they break it down.

Several studies indicate that potential milk production in humans is considerably higher than the average intake by single infants. Kaucher and colleagues (1945) measured maximum milk output with intrusive and tedious mechanical methods to extract all the mother's milk and reported that production averaged almost 1,200 g/day at 6 to 10 days post partum. This level is much higher than the 500 to 700 g/day consumed by breastfed infants at the same age (Casey et al., 1986; Saint et al., 1984).

Kaucher's methods may not have been particularly good, because others showed limits more than twice that

Women who express surplus milk for a milk bank have been shown to produce as much as 3,000 g/day (Macy et al., 1930).

As my wife and many lactating mothers who use a breast pump will be able to confirm, this isn't a relic of the 30s and 40s. If you keep pumping, you keep getting milk.

In two separate studies, milk production increased by 15 to 40% when a breast pump was used to remove additional milk after feedings (Dewey and Lönnerdal, 1986; Neville and Oliva-Rasbach, 1987).

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    $\begingroup$ I'd add that this is how biology does almost everything involving regulating production of something, from small molecules to excreted fluids to tissues: use feedback to know when to increase or decrease production, rather than producing some specific magic amount automatically. $\endgroup$ – Bryan Krause Jul 11 '18 at 23:13
  • $\begingroup$ Thanks, this is useful info. Of course, it's not enough for say that women have more milk than primates, which should be true, if, of course, primates did not have such division of labor as humans. And as we know, they don't. $\endgroup$ – rus9384 Jul 11 '18 at 23:16
  • $\begingroup$ @rus9384 I don't know enough about non-human primates to answer authoritatively. Maybe Bryan does? But I'm not sure we can make a global statement about the social structure of all primates. As far as I remember from school, there's a lot of diversity in social structure across that order. $\endgroup$ – De Novo Jul 11 '18 at 23:22
  • $\begingroup$ @DanHall, there is, but division of labor is proposed to be the effect of great level of intelligence. Lower than that of human, yet higher than what any existing primate has. $\endgroup$ – rus9384 Jul 11 '18 at 23:24
  • $\begingroup$ Well, sure women who produce for a milk bank produce more. Women who produce less don't donate milk. Quantifying outliers says nothing about how the data is distributed in the whole population. If it takes a pump to get the excess milk out, then that milk shouldn't be counted as being available in communities which lack access to that technology. $\endgroup$ – swbarnes2 Jul 12 '18 at 16:34

This, of course, would require those women to have excessive (more than needed to feed their own children) amount of milk.

No it doesn't. A wet nurse might be a woman whose infant died, or she might switch her child to all solid food or a milk substitute.

  • $\begingroup$ You seem to misunderstand what I mean by nurse. Nurse for me in hunter-gatherer society is somewhat like nurse in ants society, who deliberately cares about children (who are not necessarily her own). $\endgroup$ – rus9384 Jul 11 '18 at 18:22
  • $\begingroup$ If you are so sure that hunter-gathers and ants work the same way, why are you bothering to ask a question here? $\endgroup$ – swbarnes2 Jul 11 '18 at 18:33
  • $\begingroup$ Not the same, but similar. Also, one should not answer here something that is not the part of the question (it is just an explanation for motive) and that's not a part of biology. I don't even see any negative connection between my thoughts (regarding hunter-gatherer society) and the motive to ask. $\endgroup$ – rus9384 Jul 11 '18 at 18:37
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    $\begingroup$ Alloparenting is what's common in hunter-gatherers, the opposite of the specialization you seem to think is obviously innate and superior. $\endgroup$ – swbarnes2 Jul 12 '18 at 19:33
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    $\begingroup$ I don't think you understand how testing scientific hypotheses works...You don't make a hypothesis and then try to fit every other piece of data to it. You create a hypothesis that you can test somehow. Only once you have an overwhelming amount of support for a theory can you use it to make predictions about novel things. $\endgroup$ – Bryan Krause Jul 12 '18 at 23:50

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