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Homo naledi is a mixture of humanlike and primitive characteristics
14 November 2016
The discovery of聽Homo naledi聽has expanded the range of phenotypic variation in聽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, geometric morphometric analyses were performed on聽贬.听苍补濒别诲颈聽cranial and mandibular remains to investigate its morphological relationship with species of聽Homo听补苍诲听Australopithecus. Generalized Procrustes analysis was conducted to place聽贬.听苍补濒别诲颈聽within the pattern of known hominin skull diversity, distributions of Procrustes distances among individuals to compare聽贬.听苍补濒别诲颈听补苍诲听Homo erectus, and neighbour joining trees to investigate the potential phenetic relationships between groups. The goal is to address a set of hypotheses relating to the uniqueness of聽贬.听苍补濒别诲颈, its affinity with聽贬.听别谤别肠迟耻蝉, and the age of the fossils based on skull morphology. The results indicate that, cranially,聽贬.听苍补濒别诲颈aligns with members of the genus聽Homo, with closest affiliations to聽贬.听别谤别肠迟耻蝉. The mandibular results are less clear;聽贬.听苍补濒别诲颈聽closely associates with a number of taxa, including some australopiths. However, results also show that although聽贬.听苍补濒别诲颈聽shares similarities with聽贬.听别谤别肠迟耻蝉, some distances from this taxon - especially small-brained members of this taxon - are extreme. The neighbor joining trees place聽贬.听苍补濒别诲颈聽firmly within聽Homo. The trees based on cranial morphology again indicate a close relationship between聽贬.听苍补濒别诲颈听补苍诲听贬.听别谤别肠迟耻蝉, whereas the mandibular tree places聽贬.听苍补濒别诲颈聽closer to basal聽Homo, suggesting a deeper antiquity. Altogether, these results emphasize the unique combination of features (贬.听别谤别肠迟耻蝉-like cranium, less derived mandible) defining聽贬.听苍补濒别诲颈. The results also highlight the variability within聽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.
Lauren Schroeder et al