Since there many competing user interests, a population size greater than one is necessary to model the dynamics of user interests. The system is set up as a single-agent system, with a population size of twenty. Initially, the population is oriented to the current major user interest, namely ``Business''. Most of the profiles in the population specialize in Business news, while a relatively fewer number specialize in Politics. The user interests then gradually changes towards Politics. The profiles which retrieve political articles receive positive feedback and their fitness increases. At the same time, profiles which retrieve other kinds of articles (including Business articles) receive negative feedback and the corresponding fitness decreases.