Stable isotope studies of bone collagen are widely applied in an attempt to understand the history and range of modern human and earlier hominin diets. The nitrogen isotope system has been extensively applied to the human bioarchaeological record to predict dietary protein sources, as nitrogen isotope ratios roughly track the trophic positionality of an organism. While the ratio of nitrogen isotopes in organisms (δN) tends to be reflective of trophic position, nitrogen isotope fractionation is complex and subject to many sources of variation. This study explores how human behavior might influence this variation. We experimentally investigated the impact of food-related behaviors on the δN dietary proxy, with specific focus on selection and processing of animal food sources. In assessing putrefaction, processing, prey choice, and fuel wood, we saw that these variables generated small shifts of ∼1.5‰ or less in the δN values of food items. We conclude that scavenging as a frequent dietary adaptation may be isotopically visible, but the timing of carcass scavenging likely matters. We also posit that prey species and fuel wood species might matter for the patterning of δN shifts produced by different types of cooking. The results of this study expand the range of contributing factors to consider when utilizing the nitrogen isotope dietary proxy and open new testable questions about the use of this method in populations where complex food behavior may be common.

中文翻译：

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食品加工对膳食肉类中 δ15N 值影响的实验评估 – 对古饮食重建的影响


骨胶原的稳定同位素研究被广泛应用于试图了解现代人类和早期古人类饮食的历史和范围。氮同位素系统已广泛应用于人类生物考古记录，以预测膳食蛋白质来源，因为氮同位素比率大致跟踪生物体的营养位置。虽然生物体中氮同位素的比率 (δN) 往往反映营养位置，但氮同位素分馏很复杂，并且受到许多变异来源的影响。这项研究探讨了人类行为如何影响这种变化。我们通过实验研究了食物相关行为对 δN 饮食指标的影响，特别关注动物性食物来源的选择和加工。在评估腐败、加工、猎物选择和薪材时，我们发现这些变量对食品的 δN 值产生约 1.5‰ 或更少的小幅变化。我们的结论是，作为一种频繁的饮食适应，食腐可能在同位素上是可见的，但尸体食腐的时间可能很重要。我们还假设猎物物种和薪材物种可能对不同类型烹饪产生的 δN 变化模式很重要。这项研究的结果扩大了使用氮同位素膳食替代物时需要考虑的影响因素的范围，并提出了关于在复杂食物行为可能常见的人群中使用该方法的新的可测试问题。