Fig. 8. Contact density distribution in prokaryotic only domains (red) and eukaryotic domains (black). The binning of histograms is the same as Fig. 4a (CD bins of size 0.5); however, the data for each plot are collected for Dali domains that fall into narrow length ranges: 100-150 amino acids (a), 150-200 amino acids (b), and 200-250 amino acids (c). In all three intervals, the eukaryotic innovation domains exhibit statistically lower contact densities with KS P values <10^–5 (a), 0.02 (b), and <10^–4(c).