Variation in the durations of exclusive breastfeeding (exBF) and any breastfeeding (anyBF) is associated with socioecological factors. This plasticity in breastfeeding behavior appears adaptive, but the mechanisms involved are unclear. With this concept in mind, we investigated whether durations of exBF and anyBF in a rural Maya population covary with markers of a form of socioecological change—market integration—and whether individual factors (individual learning, physiological plasticity) and/or learning from others in the community (social learning, norm adherence) mediate these changes. Using data from 419 mother-child pairs from two Guatemalan Maya villages, we fit a bivariate linear mixed model. The model compared exBF and anyBF among children from households of varying degrees of market integration whose mothers follow what we inferred to be local infant-feeding norms. It controlled for other factors expected to affect breastfeeding durations. We found evidence that exBF is associated with whether mothers follow their population’s infant feeding norms, but no evidence that exBF is associated with the household’s level of market integration. Conversely, anyBF is significantly associated with the household’s market integration, but not with the villages’ inferred norms. Because deviations from exBF norms are likely to result in infant mortality and reduced fitness, we hypothesize that the incentive to conform is relatively strong. Relatively greater individual plasticity in anyBF allows mother-child pairs to tailor it to socioecological conditions. Deviations from anyBF norms may be tolerated because they may provide later-life health/fitness payoffs, while posing few risks to infant survival.

中文翻译：

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两个玛雅人社区的母乳喂养时间和婴儿喂养知识的社会学习

完全母乳喂养（exBF）和任何母乳喂养（anyBF）持续时间的变化与社会生态因素有关。母乳喂养行为的这种可塑性似乎是适应性的，但涉及的机制尚不清楚。考虑到这一概念，我们调查了玛雅农村人口中exBF和anyBF的持续时间是否与某种社会生态变化形式的标志（市场整合）共存，以及个体因素（个体学习，生理可塑性）和/或向其他人学习社区（社会学习，规范遵守）介导了这些变化。使用来自两个危地马拉玛雅村庄的419对母子对的数据，我们拟合了双变量线性混合模型。该模型比较了不同市场整合程度的家庭的孩子中的exBF和anyBF，这些孩子的母亲遵循我们推断的当地婴儿喂养规范。它控制了预计会影响母乳喂养时间的其他因素。我们发现有证据表明exBF与母亲是否遵循其人口的婴儿喂养规范有关，但没有证据表明exBF与家庭的市场整合水平有关。相反，任何BF与家庭的市场整合显着相关，但与村庄的推断规范无关。由于与exBF规范的偏离可能会导致婴儿死亡并降低体适能，因此我们假设顺应性的动机相对较强。任何BF中相对较高的个体可塑性都可以使母子对适应社会生态条件。可以容忍与任何BF规范的差异，因为它们可能会为以后的健康/健身带来收益，同时对婴儿生存的风险很小。