If our moral attitudes are entirely the result of nonrational factors, such as gut feelings and the absorption of cultural norms, they should either be stable or randomly drift over time, like skirt lengths or the widths of ties. They shouldn't show systematic change over human history. But they do.
I actually think that bass is probably the instrument that has evolved in a quantum leap compared to other instruments. It's the instrument that's evolved the most, especially with how it's perceived. And even how it's played, and how it's viewed from a point of view of commerce, like with the music industry.