Fig. 2.

Linear regression of frequency, variety, and dynamism of volitional behavior against evolutionary distance. The mean value of attributes from all observational episodes (n = 5–6) for each species were plotted against evolutionary distance to generate the best fitting line (bold dashes) with 95% confidence bands (light dashes) for its slope. The slopes did not differ from zero for (a) frequency (slope = 0.0013, F = 0.0064, P = 0.937), (b) variety (slope = 0.0022, F = 0.187, P = 0.675), or (c) dynamism (slope = −0.0136, F = 0.080, P = 0.783).