Comparative observations on the premolar root and pulp canal configurations of Middle Pleistocene Homo in China
Comparative observations on the premolar root and pulp canal configurations of Middle Pleistocene Homo in China
复制标题
中国中更新世人前磨牙根管形态的比较观察
DOI：
10.1002/ajpa.23777
复制
发表时间：
2019
影响因子：
2.8
通讯作者：
Zanolli Clement
中科院分区：
文献类型：
--
作者：
Pan Lei;Zanolli Clement
目的探讨中更新世居中国的古人类化石的根和根管形态。东亚地区中更新世时期的人类居住与进化动态是古人类学研究中最具吸引力的问题之一，多世系和区域变种的共存表明了一个复杂的种群相互作用情景。虽然前磨牙根管形态具有一定的系统发育、分类和功能意义，但其形态多样性、可能的进化趋势和东亚中更新世古人类的特征尚不清楚；这些种群在同源谱系中的位置（就根管和髓管结构而言）需要探索。材料与方法利用显微断层扫描技术，对中国中更新世人（N= 19）上颌前磨牙根管形态的非计量变异进行了直接观察和评估，并与来自亚洲大陆（N= 1）和爪哇（N= 2）的欧亚早更新世标本、尼安德特人（N= 28）和现代人类（N= 67）进行了比较。结果共记录了9种根管形态。总体而言，中国中更新世的记录显示出向现代人相似条件（根/管数量减少，根表面结构简化）的进化趋势。我们记录了一些原始的信号，比如在下颌前磨牙中有很高比例的托姆斯牙根。还发现了大量不完全分离的根枝和两歧根和根尖，代表了从多根到单根的进化转变。研究结果与前人关于东非、北非和欧亚大陆早更新世和中更新世人种的研究成果进行了比较。结论本研究提供了新的原始数据，结合了最新的人类化石发现，表明分析前磨牙根结构组织的变化，特别是将根/根管的形式和数量结合起来，可能有助于分类和系统发育评价。在我们的研究中，中新世直立人群体或“经典”直立人与欧亚大陆早更新世和中更新世人类的亲缘关系比与东非早更新世人类的亲缘关系更密切，这支持了欧亚大陆至少一些早更新世人类群体对晚更新世人类群体的贡献；另一方面，要清楚地追踪这些中更新世晚期人群的进化命运仍然很困难（从颅齿的角度来看，这些人群大致被划分为古人类）。为了进一步探索现代人类到来之前亚洲大陆古人类的进化趋势，需要更多的早更新世至中更新世时期的可比材料以及精确的时间框架。
ObjectivesThe aim of this study is to explore the root and root canal morphology ofHomofossil occupying China during the Middle Pleistocene period. Human occupation and evolutionary dynamics in East Asia during the Middle Pleistocene period is one of the most intriguing issues in paleoanthropology, with the coexistence of multiple lineages and regional morphs suggesting a complex population interaction scenario. Although premolar root and canal morphology has certain phylogenetic, taxonomic, and functional implications, its morphological diversity, possible evolutionary trend and characteristics regarding Middle Pleistocene hominins inhabiting East Asia are still insufficiently understood; where these populations fits within theHomolineage (with respect to root and pulp canal structure) needs to be explored.Materials and methodsUsing microtomography, we directly observed and assessed the nonmetric variability of root and canal forms in maxillary and mandibular premolars of Chinese Middle PleistoceneHomo(N= 19), and compared our observed variations with Eurasian Early Pleistocene specimens from the Asia continent (N= 1) and Java (N= 2), as well as with Neanderthals (N= 28) and recent modern humans (N= 67).ResultsA total number of nine types of root‐canal forms were recorded. As a whole, the Chinese Middle Pleistocene record shows an evolutionary trend toward a modern human‐like condition (a reduction of root/canal number and a simplification of root surface structure). We documented primitive signals like high percentage of Tomes' root in lower premolars. A considerable occurrence of incompletely separated root branches and bifid root and canal apices, representing evolutionary transformation from multi‐root to single‐root condition was also noticed. The results were compared with previous publications on Early and Middle PleistoceneHomoin East Africa, North Africa, and Eurasia.ConclusionThis work provides new original data, incorporates the latest human fossil discoveries and suggests that analyzing the variation of premolar root structural organization, notably integrating together root/canal form and number, could possibly contribute to taxonomic and phylogenetic assessments. The mid‐Middle Pleistocene populations, or “classic”Homo erectus, in our study show closer affinity to Early and Middle Pleistocene hominins in Eurasia, than to East African earlyHomo, which supports the suggestion that at least some of the Early Pleistocene hominin groups in Eurasia contribute to the later population; on the other hand, it is still difficult to clearly trace the evolutionary fate of those late Middle Pleistocene populations (roughly assigned as archaicHomo sapiensthrough a craniodental perspective). More comparable materials from the Early to Middle Pleistocene period as well as precise chronological framework is needed to further explore the evolutionary trends of archaic hominins in the Asian continent before the arrival of modern humans.