Schroeder Lauren, Scott Jill E, Garvin Heather M, Laird Myra F, Dembo Mana, Radovčić Davorka, Berger Lee R, de Ruiter Darryl J, Ackermann Rebecca R
Department of Archaeology, University of Cape Town, Rondebosch 7701, South Africa; Department of Anthropology, University at Buffalo, SUNY, Buffalo, NY 14261, USA; Evolutionary Studies Institute and Centre for Excellence in PaleoSciences, University of the Witwatersrand, Private Bag 3, Wits 2050, South Africa; Human Evolution Research Institute, University of Cape Town, Rondebosch 7701, South Africa.
Evolutionary Studies Institute and Centre for Excellence in PaleoSciences, University of the Witwatersrand, Private Bag 3, Wits 2050, South Africa; Department of Anthropology, The University of Iowa, Iowa City, IA 52242, USA; Department of Sociology and Anthropology, Metropolitan State University of Denver, CO 80217, USA.
J Hum Evol. 2017 Mar;104:124-135. doi: 10.1016/j.jhevol.2016.09.014. Epub 2016 Nov 9.
The discovery of Homo naledi has expanded the range of phenotypic variation in Homo, leading to new questions surrounding the mosaic nature of morphological evolution. Though currently undated, its unique morphological pattern and possible phylogenetic relationships to other hominin taxa suggest a complex evolutionary scenario. Here, we perform geometric morphometric analyses on H. naledi cranial and mandibular remains to investigate its morphological relationship with species of Homo and Australopithecus. We use Generalized Procrustes analysis to place H. naledi within the pattern of known hominin skull diversity, distributions of Procrustes distances among individuals to compare H. naledi and Homo erectus, and neighbor joining trees to investigate the potential phenetic relationships between groups. Our goal is to address a set of hypotheses relating to the uniqueness of H. naledi, its affinity with H. erectus, and the age of the fossils based on skull morphology. Our results indicate that, cranially, H. naledi aligns with members of the genus Homo, with closest affiliations to H. erectus. The mandibular results are less clear; H. naledi closely associates with a number of taxa, including some australopiths. However, results also show that although H. naledi shares similarities with H. erectus, some distances from this taxon - especially small-brained members of this taxon - are extreme. The neighbor joining trees place H. naledi firmly within Homo. The trees based on cranial morphology again indicate a close relationship between H. naledi and H. erectus, whereas the mandibular tree places H. naledi closer to basal Homo, suggesting a deeper antiquity. Altogether, these results emphasize the unique combination of features (H. erectus-like cranium, less derived mandible) defining H. naledi. Our results also highlight the variability within Homo, calling for a greater focus on the cause of this variability, and emphasizing the importance of using the total morphological package for species diagnoses.
纳莱迪人的发现扩展了人属的表型变异范围，引发了围绕形态进化镶嵌性的新问题。尽管其年代目前尚未确定，但其独特的形态模式以及与其他古人类分类群可能的系统发育关系表明了一种复杂的进化情况。在这里，我们对纳莱迪人的颅骨和下颌骨遗骸进行几何形态测量分析，以研究其与人类和南方古猿物种的形态关系。我们使用广义普罗克拉斯提斯分析将纳莱迪人置于已知古人类头骨多样性模式中，通过个体间普罗克拉斯提斯距离的分布来比较纳莱迪人和直立人，并使用邻接法树来研究群体之间潜在的表型关系。我们的目标是基于头骨形态解决一系列与纳莱迪人的独特性、其与直立人的亲缘关系以及化石年龄相关的假设。我们的结果表明，在颅骨方面，纳莱迪人与人类属成员一致，与直立人关系最为密切。下颌骨的结果不太明确；纳莱迪人与许多分类群密切相关，包括一些南方古猿。然而，结果也表明，尽管纳莱迪人与直立人有相似之处，但与该分类群的一些距离——尤其是该分类群中脑容量较小的成员——非常大。邻接法树将纳莱迪人稳固地置于人属之中。基于颅骨形态的树再次表明纳莱迪人和直立人之间关系密切，而下颌骨树则将纳莱迪人置于更接近早期人属的位置，表明其年代更为久远。总之，这些结果强调了定义纳莱迪人的特征（类似直立人的颅骨，不太特化的下颌骨）的独特组合。我们的结果还突出了人属内部的变异性，呼吁更加关注这种变异性的原因，并强调使用整体形态特征进行物种诊断的重要性。
