As you've described it, Adaptiveness is very economic. But there are lots of social changes that are hard to explain economically. For example, the expansion of political inclusiveness in the West (Monarchy -> Limited Voting Rights -> Universal Manhood Suffrage -> Universal Suffrage).

There are subfields within economics that attempt to explain precisely these kinds of "social change" using standard microeconomic theory (for instance, public choice).

As kings from medieval times sought to lessen their dependence on the nobility by soliciting the support of town burghers, so did the state in more modern times emancipate itself from the bourgeoisie by enfranchising and buying the votes of successively broader masses of people.

-Anthony de Jasay, The State