Recent studies have demonstrated that the outline shapes of deciduous upper and lower second molars and the deciduous upper first molar are useful for diagnosing hominin taxa—especially Homo neanderthalensis and Homo sapiens. Building on these studies, we use geometric morphometric methods to assess the taxonomic significance of the crown outline of the lower first deciduous molar (dm₁). We test whether the crown shape of the dm₁ distinguishes H. neanderthalensis from H. sapiens and explore whether dm₁ crown shape can be used to accurately assign individuals to taxa. Our fossil sample includes 3 early H. sapiens, 7 Upper Paleolithic H. sapiens, and 13 H. neanderthalensis individuals. Our recent human sample includes 103 individuals from Africa, Australia, Europe, South America, and South Asia. Our results indicate that H. neanderthalensis dm₁s cluster fairly tightly and separate well from those of Upper Paleolithic H. sapiens. However, we also found that the range of shapes in the recent human sample completely overlaps the ranges of all fossil samples. Consequently, results of the quadratic discriminant analysis based on the first 8 principal components (PCs) representing more than 90% of the variation were mixed. Lower dm1s were correctly classified in 87.3% of the individuals; the combined H. sapiens sample had greater success (90.2%) in assigning individuals than did the H. neanderthalensis sample (61.5%). When the analysis was run removing the highly variable recent human sample, accuracy increased to 84.6% for H. neanderthalensis, and 57.1% of Upper Paleolithic H. sapiens were classified correctly by using the first 4 PCs (70.3%). We conclude that caution is warranted when assigning isolated dm₁ crowns to taxa; while an assignment to H. neanderthalensis has a high probability of being correct, assignment to Upper Paleolithic H. sapiens is less certain.

最近的研究已经表明，落叶上下第二磨牙和落叶上部第一臼齿的轮廓形状可用于诊断人族类群-特别有用智人尼安德特和智人。在这些研究的基础上，我们使用几何形态计量学方法评估较低的第一落叶磨牙（dm ₁）冠轮廓的分类学意义。我们测试是否DM的王冠形状_1个区分H.尼安德特从智人和探索DM是否₁冠形状可以被用于精确地分配个人类群。我们的化石样本包括3个早期的智人7个旧石器时代智人，和13 ħ。尼安德特人。我们最近的人类样本包括来自非洲，澳大利亚，欧洲，南美和南亚的103个人。我们的结果表明，尼安德特人（H. neanderthalensis dm ₁ s）聚集非常紧密，并且与上旧石器时代的智人分离得很好。。但是，我们还发现，最近的人类样本中的形状范围与所有化石样本的范围完全重叠。因此，将基于代表变化的90％以上的前8个主成分（PC）进行二次判别分析的结果混合在一起。较低的dm1s在87.3％的个体中正确分类。相较于尼安德特人血统样本（61.5％），合并的智人样本在分配个体方面取得更大的成功（90.2 ％）。当运行分析以除去高度可变的最近人类样本时，尼安德特人嗜血杆菌的准确度提高到84.6 ％，上旧石器时代的智人的准确度提高到57.1％使用前4台PC（70.3％）正确分类了。我们得出的结论是，将孤立的dm ₁冠冠分配给分类单元时应格外小心；尽管对尼安德特人（H. neanderthalensis）的归类很可能是正确的，但对上旧石器时代的智人（H. sapiens）的归类却不太确定。