Polygyny without wealth: popularity in gift games predicts polygyny in BaYaka Pygmies

The occurrence of polygynous marriage in hunter–gatherer societies, which do not accumulate wealth, remains largely unexplored since resource availability is dependent on male hunting capacity and limited by the lack of storage. Hunter–gatherer societies offer the greatest insight in to human evolution since they represent the majority of our species' evolutionary history. In order to elucidate the evolution of hunter–gatherer polygyny, we study marriage patterns of BaYaka Pygmies. We investigate (i) rates of polygyny among BaYaka hunter–gatherers; (ii) whether polygyny confers a fitness benefit to BaYaka men; (iii) in the absence of wealth inequalities, what are the alternative explanations for polygyny among the BaYaka. To understand the latter, we explore differences in phenotypic quality (height and strength), and social capital (popularity in gift games). We find polygynous men have increased reproductive fitness; and that social capital and popularity but not phenotypic quality might have been important mechanisms by which some male hunter–gatherers sustained polygynous marriages before the onset of agriculture and wealth accumulation.

在无财富积累的狩猎采集社会中，一夫多妻婚姻的存在性至今尚未得到充分探究——这是由于该类社会的资源获取依赖男性狩猎能力，且受限于储存手段的匮乏。狩猎采集社会占据了我们智人种演化史的绝大多数时段，因此为人类演化研究提供了最为关键的视角。为阐明狩猎采集社会一夫多妻制的演化逻辑，本研究以巴亚卡俾格米人（BaYaka Pygmies）的婚姻模式为研究对象，旨在解答三大研究问题：其一，巴亚卡狩猎采集群体中一夫多妻制的发生比例；其二，一夫多妻制是否能为巴亚卡男性带来适应性收益；其三，在不存在财富不平等的背景下，巴亚卡群体中一夫多妻制存在的其他潜在解释是什么。为解答第三个研究问题，本研究考察了两类潜在影响因素：表型质量（身高与力量）以及社会资本（馈赠活动中的受欢迎程度）。研究结果显示，实行一夫多妻制的男性拥有更高的繁殖适应性；且在农业起源与财富积累出现之前，社会资本与受欢迎程度（而非表型质量）或是部分男性狩猎采集者维持一夫多妻婚姻的关键机制。