School of Archaeology and Anthropology, The Australian National University, Canberra, ACT, Australia.
Department of Integrative Biology and Physiology, University of Minnesota Medical School, Minneapolis, Minnesota.
Am J Phys Anthropol. 2020 May;172(1):25-40. doi: 10.1002/ajpa.24030. Epub 2020 Mar 13.
The aim of this study is to understand whether the shape of three sub-regions of the mandibular corpus (the alveolar arch, corpus at M and posterior symphysis) are useful for making taxonomic assessments at the genus and species levels in extant hominids.
We use data taken from 3D surface scans of the mandibular corpus of seven extant hominid taxa: Gorilla gorilla gorilla, Gorilla beringei graueri, Homo sapiens, Pan paniscus, Pan troglodytes schweinfurthii, Pongo abelii, and Pongo pygmaeus pygmaeus to generate four shape variables: alveolar arch shape (AAS), corpus shape at M (CSM ), posterior symphysis shape at the midline (PSSM), and posterior symphysis shape (PSS). To ascertain how reliable each mandibular shape variable is for assessing taxonomy, we ran canonical discriminant and discriminant function analysis, reporting cross-validated results.
Using a combination of three mandibular corpus shape variables, 99% of specimens were classified correctly for genus-level analyses. A maximum of 100% of Pan specimens, 94% of Gorilla specimens and 96% of Pongo specimens were classified correctly at the species level when up to three mandibular shape variables were included in the analyses. When mandibular corpus variables were considered in isolation, posterior symphysis shape yielded the highest overall correct classification results.
The high taxonomic classification rates at both the genus and species level, using 3D surface data and advanced quantification techniques, show that the shape of the alveolar arch, corpus at M and symphysis can distinguish extant hominid taxa. These findings have implications for assessing the taxonomy of extinct hominid specimens which preserve these mandibular sub-regions.
本研究旨在探讨下颌体的三个亚区（牙槽弓、M 部和后联合）的形状是否可用于对现生人类进行属和种水平的分类评估。
我们使用了来自 7 种现生人类分类群的下颌体 3D 表面扫描数据：大猩猩指名亚种、东非大猩猩、智人、黑猩猩、黑猩猩西部低地亚种、猩猩阿比西尼亚种和苏门答腊猩猩，生成了 4 个形状变量：牙槽弓形状（AAS）、M 部形状（CSM）、中线后联合形状（PSSM）和后联合形状（PSS）。为了确定每个下颌形状变量在分类评估中的可靠性，我们进行了典型判别和判别函数分析，并报告了交叉验证结果。
使用三个下颌体形状变量的组合，99%的标本在属水平的分类分析中得到正确分类。当分析中包含三个下颌形状变量时，最多可正确分类 100%的黑猩猩标本、94%的大猩猩标本和 96%的苏门答腊猩猩标本。当单独考虑下颌体变量时，后联合形状的总体正确分类结果最高。
使用 3D 表面数据和先进的定量技术，在属和种水平上的高分类率表明，牙槽弓、M 部和联合的形状可以区分现生人类分类群。这些发现对评估保存这些下颌亚区的灭绝人类标本的分类学具有重要意义。
