Breast Feeding Structure and Parental Investment in Papua New Guinea

许多传统和工业化社会的父母被认为根据可用资源的总池以及子女的年龄、性别和感知的活力或状况，对给定的子女进行不同的投资。进化生态学为理解这些不同的父母投资策略提供了一个框架。父母投资的进化模型预测，父母会根据当前投资和资源替代使用的可能健康回报，调整分配给孩子的资源的大小和安排。然而，到目前为止，很少有研究试图测试从这一理论体系明确派生出来的假设。该项目试图使用一项关于母子亲近程度的观察性研究的数据，以及巴布亚新几内亚非洲人的母乳喂养和补充实践的数据，来检验进化父母投资理论的几个预测。长时间哺乳会导致长时间的无排卵期以及产妇能量储备的长期下降，这已被证明会影响产妇的健康和生存。因此，哺乳是母亲在新生儿身上花费的最昂贵的投资形式之一，应根据母婴的个体特征而有系统地变化。这项研究将提供有关传统社会中婴儿喂养模式变化的重要数据，并将有助于确定特定儿童在何种条件下生长发育迟缓、发病率和死亡风险增加。它还将为进化的父母投资理论提供首批关键测试之一。

Parents in many traditional and industrialized societies have been seen to invest differentially in given offspring according to the total pool of resources available, as well as the offspring's age, gender, and perceived vigor or condition. The discipline of evolutionary ecology offers a framework for understanding these differential parental investment strategies. Evolutionary models of parental investment predict that parents adjust the magnitude and scheduling of resources allocated to their children according to the likely fitness payoffs of current investments and those from alternative uses of resources. To date, however, little research has attempted to test hypotheses explicitly derived from this body of theory. This project seeks to test several predictions of evolutionary parental investment theory using data from an observational study of mother-offspring proximity, and breast-feeding and supplementation practices among the Au of Papua New Guinea. Prolonged lactation leads to a protracted anovulatory period as well as to long-term declines in maternal energy reserves which have been documented to affect maternal health and survival. As such, lactation is one of the costliest forms of investment expended by mothers on their newborn offspring and should vary systematically with individual characteristics of the mother and child. This study will yield important data on variation in infant feeding patterns in a traditional society and will help to identify the conditions under which specific children are at elevated risk of growth faltering, morbidity, and death. It will also provide one of the first critical tests of evolutionary parental investment theory.