Derek is working on a thesis on the changes in social behavior in the context of finding partners. An important part of his study concerns the various practices followed by males and females over the course of generations and how they have gradually transformed into our current social norms. Derek can be called a(n) psychologist.

Derek is an evolutionary psychologist.

Explanation:

To study the human behavior adaptation along with passage of time is called evolutionary psychology.

Same here, Derek thesis is the best example of evolutionary psychology. Derek studied the continuous changes in social behavior through generation to generation by both males and females to current social norms.