Figure 2.

(a) Brain size variation between breeds; table 2 in electronic supplementary material, data D6 for statistics. (b) MZW variation between breeds, measured against overall size (PTL = posterior tooth row length); table 3 in electronic supplementary material, data D6 for statistics. Silhouettes credited to: DFoidl (modified by T. Michael Keesey) (aurochs), https://creativecommons.org/licenses/by-sa/3.0/; Steven Traver (dairy); Tracy Heath (beef); and Mariana Ruiz Villarreal (bullfighting). (Online version in colour.)