Robert Cornelius took a self-portrait on a daguerreotype in 1839, which is believed to be the first American portrait, but it wasn't until the 2000s that "selfie" became a word. It was the Oxford English Dictionary's word of the year in 2013. The gap between the first instance of self-portraiture by camera and the proliferation of the term "selfie" more than a century later is an (extreme) example of

Cultural lag  

Explanation:

 The cultural lag is the term which is used for the cultural idea or concept that the culture specifically taking a lots of time for the solving the various types of social issues and the innovation of the various types of technology that is caused by the lag.

 The main causes of the cultural lag is due to the technological advancement, cultural change in the society, globalization and change in the user needs.

According to the given question, the cultural lag is  basically explain the gap between the given instances based on the self-portraiture by the camera and the selfie.    

 Therefore, Cultural lag is the correct answer.

manifest functions are the recognized and intended consequences of any social pattern, while latent functions are those unrecognized and unintended consequences. to analyze the manifest functions of any social institution, we have to study its contribution to the continuation of a group, community, or society.

answer; how people relate to each other and influence each other;