The University of Michigan, Museum of Anthropology, Ann Arbor, MI 48109, USA.
J Hum Evol. 2011 Jan;60(1):34-46. doi: 10.1016/j.jhevol.2010.08.006. Epub 2010 Nov 10.
Age of tooth emergence is a useful measure of the pace of life for primate species, both living and extinct. A recent study combining wild chimpanzees of the Taï Forest, Gombe, and Bossou by Zihlman et al. (2004) suggested that wild chimpanzees erupt teeth much later than captives, bringing into question both comparisons within the hominin fossil record and assessment of chimpanzees. Here, we assess the magnitude of the "wild effect" (the mean difference between captive and wild samples expressed in standard deviation units) in these chimpanzees. Tooth emergence in these wild individuals is late, although at a more moderate level than previously recorded, with a mean delay conservatively estimated at about 1 SD compared to the captive distributions. The effect rises to 1.3 SD if we relax criteria for age estimates. We estimate that the mandibular M1 of these wild chimpanzees emerges at about 3 (2)/(3)-3 ¾ years of age. An important point, often ignored, is that these chimpanzees are largely dead of natural causes, merging the effect of living wild with the effect of early death. Evidence of mortality selection includes, specifically: younger deaths appear to have been more delayed than the older in tooth emergence, more often showed evidence of disease or debilitation, and revealed a higher occurrence of dental anomalies. Notably, delay in tooth emergence for live-captured wild baboons appears lower in magnitude (ca. 0.5 SD) and differs in pattern. Definitive ages of tooth emergence times in living wild chimpanzees must be established from the study of living animals. The fossil record, of course, consists of many dead juveniles; the present study has implications for how we evaluate them.
牙齿萌出的年龄是衡量灵长类物种（包括现存和已灭绝物种）生活节奏的有用指标。最近的一项研究结合了泽尔曼等人（2004 年）对泰森林、贡贝和博苏的野生黑猩猩的研究结果，表明野生黑猩猩的牙齿萌出时间比圈养的黑猩猩晚，这不仅对人化石记录中的比较提出了质疑，也对黑猩猩的评估提出了质疑。在这里，我们评估了这些黑猩猩的“野生效应”（圈养和野生样本之间的平均值差异，用标准差单位表示）的幅度。这些野生个体的牙齿萌出时间较晚，尽管比之前记录的水平稍温和，但与圈养分布相比，平均延迟被保守估计为约 1 个标准差。如果我们放宽年龄估计的标准，这个效应上升到 1.3 个标准差。我们估计这些野生黑猩猩的下颌 M1 大约在 3 （2）/（3）-3 ¾ 岁时萌出。一个重要的观点是，这些黑猩猩大多因自然原因死亡，将野生个体的生活效应与早逝的效应融合在一起。死亡率选择的证据包括：死亡年龄较小的个体在牙齿萌出时似乎比年龄较大的个体延迟更久，更经常表现出疾病或衰弱的迹象，并且牙齿异常的发生率更高。值得注意的是，活捕获的野生狒狒的牙齿萌出延迟程度较小（约 0.5 个标准差），而且模式不同。要确定生活在野外的黑猩猩的牙齿萌出时间的明确年龄，必须从对生活在野外的动物的研究中得出。化石记录当然包含许多死亡的幼年个体；本研究对我们如何评估这些幼年个体具有重要意义。
