Doctoral Dissertation Improvement: Testing the relationship between nasal traits and the anterior dentition in Homo

虽然面部中部（鼻子及其周围区域）被认为是解剖学的一个方面，受到呼吸功能的高度限制，但化石人类物种和活人之间的面部中部形式存在明显差异。这种变化的原因仍然没有完全弄清楚。特别是一个鼻子特征，鼻子内部底部（内鼻底）明显凹陷的形状，以前被认为是尼安德特人适应寒冷气候的一种方式，以帮助温暖吸入的空气。然而，最近的研究却对此表示怀疑。构成大部分鼻囊的骨骼，成对的上颌骨，也容纳上牙列，并且必须对呼吸和咀嚼施加在它们身上的竞争性生物约束做出反应。该项目的初步数据表明，儿童时期门牙的发育可能是内鼻底形状差异的最终原因。博士生Christina Nicholas（爱荷华州大学）在Robert Franciscus博士的监督下进行了这个项目，测试了内鼻形状的各个方面，例如内鼻底凹陷与没有凹陷，与前牙特征的变化相关的假设。如果是这样的话，这可能意味着一些内鼻特征是进化因素作用于前牙特征的次要结果（例如，牙根大小和牙齿萌出的时间）。通过对现代人类的CT扫描和化石人类的3D表面扫描样本进行分析，研究内鼻特征和前牙特征之间的关系。本研究项目以从出生到成年早期的个体为样本，从发育的角度研究面中部的进化。尽管内鼻底在儿童面部手术中起着重要作用，如矫正鼻中隔偏曲，但目前对内鼻底形状的发展知之甚少。因此，该项目的结果不仅对生物人类学，而且对临床领域，如儿童颌面外科和牙周病，都具有明显的相关性。该项目还将有助于培养一名女科学家。

While the mid-face (the nose and the region around it) is argued to be an aspect of anatomy that is highly constrained by the need to function in respiration, there are obvious differences in mid-facial form between both fossil human species and populations of living humans. The cause of this variation is still not entirely understood. One nasal trait in particular, a distinctly depressed shape to the bottom of the inside of the nose (the internal nasal floor), has previously been argued to be a Neanderthal adaptation to cold climates to help warm inhaled air. Recent research, however, has cast this into doubt. The bones which makes up the majority of the nasal capsule, the paired maxillae, also house the upper dentition and must respond to the competing biological constraints that respiration and mastication place on them. Pilot data for this project indicate that the development of the front teeth during childhood may be the ultimate cause for shape differences in the internal nasal floor. This project by doctoral student Christina Nicholas (University of Iowa), under the supervision of Dr. Robert Franciscus, tests the hypothesis that aspects of the shape of the internal nose, such as internal nasal floor depression versus the lack of depression, are correlated with variation in anterior dental traits. If so, this may imply that some internal nasal traits are a secondary result of evolutionary factors acting upon anterior dental traits (e.g., tooth root size, and timing of tooth eruption). A sample of CT scans of recent humans and 3D surface scans of fossil humans will be analyzed to examine the relationship between internal nasal traits and anterior dental traits.This research project takes a developmental perspective to investigating mid-facial evolution, with a sample composed of individuals from birth through young adulthood. Little is currently known about the development of internal nasal floor shape, despite the fact that the internal nasal floor plays an important role in pediatric facial surgeries such as the realignment of deviated nasal septa. The results of this project thus have clear relevance not only for biological anthropology, but also clinical areas such as pediatric maxillo-facial surgery and orthodontia. This project also will contribute to training a female scientist.