Smith Tanya M, Boesch Christophe
Department of Human Evolutionary Biology, Harvard University, Cambridge, MA, 02138.
Department of Primatology, Max Planck Institute for Evolutionary Anthropology, Leipzig, D-04103, Germany.
Am J Phys Anthropol. 2015 Aug;157(4):556-70. doi: 10.1002/ajpa.22741. Epub 2015 Mar 27.
Developmental defects in teeth (accentuated lines and hypoplasias) have played a critical role in studies of childhood disease, nutrition, weaning, environmental variation, and early mortality. While these enigmatic structures have been lauded for their potential insights into human evolution, few studies have examined defects in individuals of known histories.
Here we document defects in the molars of three wild juvenile chimpanzees from the Taï forest (Pan troglodytes verus) and compare them with behavioral, epidemiological, and environmental records.
Accentuated lines of differing intensities were found throughout molar crown and root growth, and were most common in a juvenile who demonstrated slow skeletal growth and prolonged maternal dependence. These defects were observed in association with some but not all injuries and disease outbreaks in this community. A 10-year record of accentuated line frequency across individuals shows a significant negative correlation with rainfall, but does not correlate with fruit availability or reveal significant annual trends. Several hypoplasias formed between ∼0.6 and 5.8 years of age on molar crowns and roots of the three individuals, however, available behavioral and epidemiological records do not explain their causation.
While teeth may provide precise and accurate records of illness and trauma in some cases, inferring seasonal cycles, social stress, or weaning in living or fossil primate dentitions requires additional evidence beyond the presence, absence, or degree of expression of these defects. Studies that microsample bulk and trace elements may provide a more secure context for the interpretation of environmental, physiological, and dietary changes that impact dental tissue formation.
牙齿发育缺陷（加重线和发育不全）在儿童疾病、营养、断奶、环境变化和早期死亡率的研究中发挥了关键作用。虽然这些神秘的结构因其对人类进化的潜在见解而受到赞誉，但很少有研究考察已知历史个体的缺陷情况。
在此，我们记录了来自塔伊森林（黑猩猩指名亚种）的三只野生幼年黑猩猩臼齿的缺陷，并将它们与行为、流行病学和环境记录进行比较。
在整个臼齿冠部和根部生长过程中均发现了不同强度的加重线，在一只骨骼生长缓慢且长期依赖母猩猩的幼年黑猩猩中最为常见。在该群体中，这些缺陷与部分但并非所有的受伤和疾病爆发有关。一项关于个体间加重线频率的10年记录显示，其与降雨量呈显著负相关，但与水果供应量无关，也未显示出明显的年度趋势。在这三只个体的臼齿冠部和根部，约0.6至5.8岁之间形成了几处发育不全，然而，现有的行为和流行病学记录无法解释其成因。
虽然牙齿在某些情况下可能提供疾病和创伤的精确记录，但推断现存或化石灵长类动物牙列中的季节循环、社会压力或断奶情况，除了这些缺陷的存在、缺失或表现程度之外，还需要额外的证据。对大量元素和微量元素进行微采样的研究可能为解释影响牙齿组织形成的环境、生理和饮食变化提供更可靠的背景。
