Extended Data Fig. 6: Principal component and cluster analysis.
From: Drimolen cranium DNH 155 documents microevolution in an early hominin species
Principal component analysis of 19 scale-adjusted craniofacial dimensions (Supplementary Data) were performed on chimpanzees (green) and fossil hominins (P. robustus = red, P. boisei = orange, Au. africanus = blue, early Homo = black) in order to convert the morphometric data into statistically independent variables to be used as input for cluster analysis. a, Plot of PC1 vs. PC2. b, PC3 vs. PC 4. PC 1 accounts for 34.5% of the total variance, PC2 for 28.5%, PC3 for 8.5%, and PC4 for 7.6%. PC1 and PC4 reflect interactions between facial height and minimum frontal breadth, albeit in inverse ways (PC1 loadings: Scale-adjusted Superior Facial Height = -0.51, Scale-Adjusted Nasal Height = -0.43, Scale-Adjusted Minimum Frontal Breadth = 0.44; PC4 loadings: Scale-adjusted Superior Facial Height = 0.41, Scale-Adjusted Minimum Frontal Breadth = 0.49). PC2 reflects palate shape (PC2 loadings: Scale-adjusted Outer Alveolar Breadth = -0.41, Scale-adjusted Interalveolar Distance at P3 = 0.43). PC3 reflects alveolar shape (PC3 loadings: Scale-adjusted Alveolar Height = 0.39, Scale-adjusted Maxilloalveolar length = 0.41). c, Dendrogram of UPGMA of the 19 sets of component scores (accounting for 100% of the total variance) showing that DNH 155 clusters with DNH 7 within P. robustus and Paranthropus clusters.
