The second theory proposed by London and Palen is based on a sociocultural explanation of gentrification. This theory argues that values, sentiments, attitudes, ideas, beliefs, and choices should be used to explain and predict human behavior, not demographics, or "structural units of analysis" (i.e., characteristics of populations). This analysis focuses on the changing attitudes, lifestyles, and values of the middle- and upper-middle-class of the 1970s. They were becoming more pro-urban than before, opting not to live in rural or even suburban areas anymore. These new pro-urban values were becoming more salient, and more and more people began moving into the cities. London and Palen refer to the first people to invade the cities as "urban pioneers". These urban pioneers demonstrated that the inner-city was an "appropriate" and "viable" place to live, resulting in what is called "inner city chic". The opposing side of this argument is that dominant, or recurring, American values determine where people decide to live, not the changing values previously cited. This means that people choose to live in a gentrified area to restore it, not to alter it, because restoration is a "new way to realize old values".