Figure 1.

(a and b) Innovation frequencies and executive brain ratio. Frequencies are corrected for research effort by taking residuals from a natural log–log plot through the origin of innovation frequency against research effort. (a) The raw data, with each point representing one species (r = 0.34, F_1,30 = 16.70, P < 0.0005). Stephan et al. (53) generally chose a single representative from each genus for brain volume measurement, so this species-level analysis is effectively similar to a genus-level analysis. (b) Independent contrast data (r = 0.18, F_1,29 = 7.66, P < 0.01). (c and d) Social learning frequencies, corrected for research effort, and executive brain ratio. (c) The raw data, with each point representing one species (r = 0.48, F_1,30 = 29.49, P < 0.0001). (d) Independent contrast data (r = 0.13, F_1,29 = 5.55, P < 0.05). Similar relationships were found between corrected tool use frequency and executive brain ratio (across-species: r = 0.40, F_1,30 = 21.46, P < 0.0001; independent contrasts: r = 0.17, F_1,29 = 7.28, P < 0.05).