You don't have to compare brain-mass/body-mass. You have to compare brain-mass/body-mass^(2/3).
> This phenomenon can be described by an equation of the form E = CS^r, where E and S are brain and body weights, r a constant that depends on animal family (but close to 2/3 in many vertebrates
> This phenomenon can be described by an equation of the form E = CS^r, where E and S are brain and body weights, r a constant that depends on animal family (but close to 2/3 in many vertebrates