Table_5_Ontogenetic Dietary Shifts and Microscopic Tooth Wear in Western Chimpanzees.xlsx

Microscopic tooth wear studies on primates have largely focused on interspecific dietary comparisons, while few have addressed intraspecific variations, such as those among age groups. Here, we examined to what extent dietary shifts during ontogeny can be revealed from microscopic tooth wear in a western chimpanzee population using 3D surface texture (3DST) analysis. To this end, we analyzed feeding observation data of 14 chimpanzees of the Taï National Park (Ivory Coast) and matched them to 3DST data analyzed on two wear facets (f9, f3) of deciduous fourth premolars and permanent molars of 41 specimens (infants, juveniles, adolescents, adults) of the same population. We expected to find an age-dependent increase in texture complexity resulting from the more frequent consumption of seeds and insects in older compared to younger individuals. Furthermore, we expected the introduction of phytolith-producing plants to the diet of post-weaned individuals to result in many small and parallel-orientated 3DST features in juveniles, adolescents and adults compared to infants. We found that the 3DST pattern did not mirror the observed increase in dietary breadth from infants to adults. However, we found that age-dependent differences in the consumption of phytolith-producing plants were reflected to some extent in the 3DST pattern: infants and adolescents who spent more time feeding on phytolith-producing plants than older individuals had more parallel orientated 3DSTs with higher peaks, while adults had flatter and more randomly orientated 3DST features. Our results suggest that phytoliths as small abrasive particles may be of greater importance for the 3DST formation than food categories, such as fruits, leaves or seeds. However, compared to the variation in the feeding data, 3DST results show only little variation among age groups. We conclude that 3DST does not explicitly reflect ontogenetic dietary changes in chimpanzees. Rather, other factors, such as individual- or sex-based feeding habits as well as seasonal variation in dust accumulation, may be of greater importance for 3DST formation.针对灵长类的微观牙齿磨损研究大多聚焦于种间饮食差异比较，而针对种内变异（如不同年龄组间的差异）的研究则相对匮乏。本研究利用三维表面纹理（3D surface texture, 3DST）分析，探究了西部黑猩猩种群个体发育过程中的饮食转变可在多大程度上通过微观牙齿磨损体现。为此，我们分析了科特迪瓦塔伊国家公园14只黑猩猩的取食观测数据，并将其与该种群41份标本（涵盖幼崽、幼年、亚成年、成年个体）的乳第四前臼齿和恒臼齿的两个磨损面（f9、f3）的三维表面纹理数据进行匹配。我们预期，相较于年幼个体，年长个体更频繁取食种子与昆虫，其牙齿纹理复杂度会随年龄增长而升高。此外，我们假设断奶后个体的饮食中加入产植硅体（phytolith）植物，因此与幼崽相比，幼年、亚成年及成年个体的牙齿表面会呈现更多小型、定向平行的三维表面纹理特征。研究发现，三维表面纹理模式并未反映出从幼崽到成年个体饮食广度的观测性增长。不过，取食产植硅体植物的年龄相关差异在一定程度上体现在三维表面纹理模式中：相较于成年个体，花费更多时间取食产植硅体植物的幼崽与亚成年个体，其牙齿表面具有更多定向平行的三维纹理及更高的峰点；而成年个体的纹理则更为平坦且定向随机。我们的研究结果表明，作为小型磨蚀颗粒的植硅体，其对三维表面纹理形成的影响可能比水果、叶片或种子等食物类别更为显著。然而相较于取食数据的变异程度，三维表面纹理结果在不同年龄组间仅表现出微弱差异。我们认为，三维表面纹理并未明确反映黑猩猩个体发育过程中的饮食变化。其他因素，例如个体或性别相关的取食习惯，以及灰尘堆积的季节性变化，可能对三维表面纹理的形成具有更为重要的影响。