Using Spectral-GEM four dimensions are significant (Fig. 4). The first two dimensions separate the continental clusters, similar to PCA. In the third and fourth dimensions, the European clusters separate more distinctly than they did for PCA. For these higher dimensions, the samples from other continents plot near to the origin, creating a cleaner picture of ancestry. Six homogeneous clusters are discovered, three European clusters, an African American cluster, and two Indian clusters.
