McElreath Richard, Koster Jeremy
Department of Anthropology and Center for Population Biology, University of California, Davis, Davis, CA, 95616, USA,
Hum Nat. 2014 Mar;25(1):100-20. doi: 10.1007/s12110-014-9193-4.
Distributions of human foraging success across age have implications for many aspects of human evolution. Estimating the distribution of foraging returns is complicated by (1) the zero-inflated nature of hunting returns, as many if not most trips fail, and (2) the substantial variation among hunters, independent of age. We develop a multilevel mixture analysis of human foraging data to address these difficulties. Using a previously published 20-year record of hunts by 147 individual Aché hunters in eastern Paraguay, we estimate returns-by-age functions for both hunting failures and the size of harvests, while also estimating the heterogeneity among hunters. Consistent with previous analyses, we find that most hunters peak around 40 years of age. We can also show, however, that much more of the variation among Aché hunters arises from heterogeneity in failure rates (zero returns), not harvest sizes. We also introduce a new R package, glmer2stan, to assist in defining and fitting similar multilevel mixture models.
人类觅食成功率随年龄的分布对人类进化的许多方面都有影响。估计觅食回报的分布很复杂，原因有两点：一是狩猎回报具有零膨胀性质，因为即便不是大多数，也有许多次狩猎会失败；二是猎人之间存在很大差异，且与年龄无关。我们开发了一种人类觅食数据的多层次混合分析方法来解决这些难题。利用之前发表的巴拉圭东部147名阿切族个体猎人长达20年的狩猎记录数据，我们估计了狩猎失败和收获量的年龄回报函数，同时也估计了猎人之间的异质性。与之前的分析一致，我们发现大多数猎人在40岁左右达到峰值。然而，我们还可以表明，阿切族猎人之间更多的差异来自失败率（零回报）的异质性，而非收获量的异质性。我们还引入了一个新的R包glmer2stan，以协助定义和拟合类似的多层次混合模型。
