Does ancient human dental enamel record short-term seasonality? Investigating time-lines in teeth with computed tomography and oxygen isotopes.

古代人类牙釉质是否记录了短期季节性？

• 批准号: NE/F018096/2
• 负责人: Janet Montgomery
• 金额: $ 8.59万
• 依托单位: Durham University
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2011
• 资助国家: 英国
• 起止时间: 2011 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=NE%2FF018096%2F2
• 关键词: Does; ancient; human; dental; enamel

A human tooth crown holds a mini-archive of information recording the diet, climate and residence of its owner. This information allows us to reconstruct what an individual was eating, and what the environmental conditions were in the past. In particular, if we can construct a temporal sequence for an individual we can also determine how they moved around and utilized this environment, and what seasonal changes in temperature were experienced. We know this can be done from the enamel of the molar teeth of cattle and sheep where there is a relatively straightforward 'time-line' spanning one or more years from the top of the tooth towards the root. These estimates for tooth crown development have been confirmed by recent isotopic studies that demonstrate seasonally distinct signatures rather than an averaged value. Human teeth, however, are very different in how they form and in their final, bulbous shape. Although the sequence of human tooth formation and eruption is well established, the pattern of enamel mineralization is very poorly understood. An initial organic scaffold of enamel is laid down over regular time periods producing a visible laminated structure (Lines of Retzius). The mineralization process, in which enamel forms within and eventually replaces the organic framework, is extremely complex and may progress spatially in several directions at once. Thus human enamel does not closely follow the 'time-line' of organic deposition, or at least, not in a straightforward chronological manner. It has been proposed that enamel mineralizes from the biting edge down, from the inside out, from the outside in, along the lines of organic matrix deposition and that thin enamel mineralizes before thick. We need to know the length of time that mineralization takes to complete, whether enamel simply records an averaged value for the whole period throughout its depth and across its surface, and if, where, and in what direction, the passage of time is recorded. Understanding this pattern is essential if we are to extract time-series information from human tooth crowns, and to interpret this data rigorously. The problem has been impossible to address in living children without repeated X-ray or large-scale extraction of developing teeth. Since these are ethically unacceptable, pigs have been used as the closest human proxies. A new approach has been identified. Archaeological skeletal collections contain many children who died whilst their teeth were still developing. The processes of tooth mineralization can be investigated using computed tomography (CT), even for teeth encased within the jaw. The method is non-destructive, repeatable and highly sensitive to differences in tissue density. A pilot study showed that fully mineralized enamel can be differentiated from incompletely mineralized enamel within a single tooth, and the difference quantified and viewed in 3D. This study will obtain multi-slice, CT scans from developing tooth crowns (incisors, canines, premolars and molars). In total, 408 teeth from over 100 juvenile skeletons curated at the University of Bradford will be scanned to investigate progressive stages of mineralization in each of the 10 selected tooth categories. Using specialized MIMICS software, 3D coloured images and animations will be produced to track the advancing front of mineralizing enamel. Where potential 'time-lines' are identified, we will test them in fully developed modern and ancient teeth using a laser to sample along the length of the line. If the passage of time is recorded in the enamel, the oxygen isotope ratios along the line should vary in a regular manner because they are sensitive to changes in climate, particularly temperature differences between summer and winter. However, if they do not vary or if variation is random, irregular and not reproducible between teeth developing at the same time in a single individual, short-term seasonality may not be preserved in human enamel.

一颗人类牙冠保存着一个小型信息档案，记录着它的主人的饮食、气候和住所。这些信息使我们能够重建一个人的饮食，以及过去的环境条件。特别是，如果我们可以为个体构建一个时间序列，我们也可以确定他们是如何移动和利用这个环境的，以及经历了什么季节的温度变化。我们知道这可以从牛羊臼齿的牙釉质中完成，因为从牙齿顶部到根部有一个相对简单的“时间线”，跨越一年或更长时间。最近的同位素研究证实了这些对牙冠发育的估计，这些研究显示出季节性的不同特征，而不是平均值。然而，人类牙齿的形成方式和最终的球茎形状都大不相同。虽然人类牙齿形成和出牙的顺序已经确定，但牙釉质矿化的模式却知之甚少。最初的有机牙釉质支架在一定的时间内铺设，产生可见的层压结构（Retzius线）。在矿化过程中，牙釉质在有机框架内形成并最终取代有机框架，这一过程极其复杂，可能在空间上同时向几个方向发展。因此，人类的牙釉质并不密切遵循有机沉积的“时间线”，或者至少不是以直接的时间顺序进行的。有人提出，牙釉质矿化是从咬边向下，从内到外，从外到内，沿着有机基质沉积的路线，薄的牙釉质矿化在厚的牙釉质矿化之前。我们需要知道完成矿化所需的时间长度，牙釉质是否只是记录了整个时期在其深度和表面上的平均值，以及时间的流逝是否，在哪里，以什么方向被记录下来。如果我们要从人类牙冠中提取时间序列信息，并严格解释这些数据，了解这种模式是必不可少的。如果不反复进行x光检查或大规模拔除发育中的牙齿，这个问题就不可能在活着的儿童中得到解决。由于这在伦理上是不可接受的，猪被用作最接近人类的替代品。已经确定了一种新的方法。考古收集的骨骼中有许多孩子在牙齿还在发育的时候就死了。牙齿矿化的过程可以使用计算机断层扫描（CT）进行调查，甚至对于牙齿包裹在颌骨内。该方法具有非破坏性、可重复性和对组织密度差异高度敏感的特点。一项初步研究表明，在一颗牙齿中，完全矿化的牙釉质可以与不完全矿化的牙釉质区分开来，并且可以在3D中量化和观察差异。本研究将对发育中的牙冠（门牙、犬齿、前磨牙和磨牙）进行多层CT扫描。布拉德福德大学（University of Bradford）将对来自100多具青少年骨骼的408颗牙齿进行扫描，以调查10种选定牙齿类别中每一种的矿化进展阶段。使用专业的MIMICS软件，将制作3D彩色图像和动画来跟踪矿化牙釉质的推进前沿。一旦确定了潜在的“时间线”，我们将在完全发育的现代和古代牙齿中使用激光沿着线的长度取样进行测试。如果在牙釉质中记录了时间的流逝，那么沿着这条线的氧同位素比率应该有规律地变化，因为它们对气候的变化很敏感，尤其是夏季和冬季的温差。然而，如果它们没有变化，或者在同一个人同时发育的牙齿之间的变化是随机的、不规则的和不可复制的，那么人类牙釉质可能不会保留短期的季节性。

项目成果

Crystallographic texture and mineral concentration quantification of developing and mature human incisal enamel.

• DOI: 10.1038/s41598-018-32425-y
• 发表时间: 2018-09-27
• 期刊: Scientific reports
• 影响因子: 4.6
• 作者: Al-Mosawi M;Davis GR;Bushby A;Montgomery J;Beaumont J;Al-Jawad M
• 通讯作者: Al-Jawad M

Mobility, mortality, and the middle ages: identification of migrant individuals in a 14th century black death cemetery population.

流动性、死亡率和中世纪：14 世纪黑死病墓地人口中移民个体的识别。

• DOI: 10.1002/ajpa.22194
• 发表时间: 2013
• 期刊: American journal of physical anthropology
• 影响因子: 2.8
• 作者: Kendall EJ

'Impious Easterners': Can Oxygen and Strontium Isotopes Serve as Indicators of Provenance in Early Medieval European Cemetery Populations?

• DOI: 10.1179/1461957112y.0000000001
• 发表时间: 2012-04-01
• 期刊: EUROPEAN JOURNAL OF ARCHAEOLOGY
• 影响因子: 1.5
• 作者: Brettell, Rhea;Evans, Jane;Montgomery, Janet
• 通讯作者: Montgomery, Janet

Cattle Management for Dairying in Scandinavia's Earliest Neolithic.

• DOI: 10.1371/journal.pone.0131267
• 发表时间: 2015
• 期刊: PloS one
• 影响因子: 3.7
• 作者: Gron KJ;Montgomery J;Rowley-Conwy P
• 通讯作者: Rowley-Conwy P

Comparing apples and oranges: Why infant bone collagen may not reflect dietary intake in the same way as dentine collagen.

• DOI: 10.1002/ajpa.23682
• 发表时间: 2018-11
• 期刊: American journal of physical anthropology
• 影响因子: 2.8
• 作者: Beaumont J;Atkins EC;Buckberry J;Haydock H;Horne P;Howcroft R;Mackenzie K;Montgomery J
• 通讯作者: Montgomery J