Can infants receive a message about their environment — about how they should behave once up and about, to better fit it — from the milk they drink from their mother’s breast?
That would be something. And a new study of rhesus macaque monkeys suggests that it does happen. Sort of.
In a ScienceDaily article, Baby Monkeys Receive Signals Through Their Mother’s Breast Milk That Affect Behavior and Temperament, I learned . . .
Scientists from the Smithsonian Institution and the University of California, Davis are using this natural variation in breast milk quality and quantity to show that a mother’s milk sends a reliable signal to infants about their environment. This signal may program the infant’s behavior and temperament according to expectations of available resources and discourages temperaments that prove risky when food is scarce. [bold mine]
In the experiment, the researchers manipulated one variable, the richness of mothers’ milk (via their diets) to see if it would influence another variable, the subsequent temperament and behavior of the infants fed on this milk. And yes, they discovered a difference.
At 3 to 4 months old, each infant was temporarily separated from its mother and assessed according to its behavior and temperament. The study found that infants whose mothers had higher levels of milk energy soon after their birth coped more effectively (moved around more, explored more, ate and drank) and showed greater confidence (were more playful, curious and active). Infants whose mothers had lower milk energy had lower activity levels and were less confident when separated from their mother.
While this finding is very interesting, as a critical thinker I am left with questions. Here are two:
1. Can we really use words like signal and message to describe what transpires? Those words imply both a sort of information sent, vs. say, a molecular triggering, as they also imply an intellectual deciphering of the information. This, I believe, is misleading to some degree.
2. Is it possible that the quality of a mother’s milk reflects her social status as much as it does the general availability of food in the environment? Mothers at the bottom of the macaque hierarchy, and macaques are extremely hierarchically-oriented animals, may have lesser access to quality foods and greater exposure the stress and factors that could influence the quality of their milk. To me, this would make good sense of an infant’s subsequently less-risky behavior. When your mother is at the bottom of the hierarchy and/or has poor quality relationships, and your mother is your number one form of early social support, it pays not to behave in a risky manner. Walk more softly, otherwise you could get chased and bitten and perhaps exiled to social Siberia. Which isn’t good for survival. Hmm.
Nonetheless, the data generated from the study, an experiment, provided me with good food for thought. So to speak.
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Tags: evolution, primates, psychology
March 31st, 2010 at 6:46 pm
>higher levels of milk energy
I.e. higher fat or sugar content. Better food makes better bodies makes happier children. This could be a response to better nutrition.
Status of the mother? From what I read this was not done in the wild but in a controlled environment. How about this, mother genitally less able produces less able offspring.