Culture is the collection of individual beliefs, habits, etc. Thus selection on the individual changes the culture, which changes the selective forces being exerted on the individual. I see an action by an individual. Then I see another man who does not jump off the bridge. Unfortunately this is the same problem that all sciences face.
Economists do use data collected from the observation of human behavior.
Models are tested using this data. Alternative models generally do not perform well. There is inertia in economics, just as in any field. However, it is not a priesthood. My daughter is not going to be happy.