Before revision:  While no single theory can explain all scales , which appear to evolve according to different selection pressures, the simplest harmonicity-based, imperfect-fifths packing model best fits the empirical data.
After revision:  While no single theory can explain all scales , which appear to evolve according to various selection pressures, the simplest harmonicity-based, imperfect-fifths packing model best fits the empirical data.