Higher spin theories have been regarded so far as an interesting but somewhat exotic topic in theoretical physics. I would like to show in this talk that higher spins fields appear naturally in any field theory and are more familiar to us than naively expected. I will consider free scalar and fermion theories in various dimensions (3,4,5,6) coupled to external sources with various spins and show by computing the one-loop two-point correlators that such simple models know about the (linearized classical) dynamics of these sources. The next step consists in studying the three-point functions i.e. the interaction and see whether there exist consistent solutions by comparing interactions and symmetries. This research is motivated by the quest for consistent theories with infinite many fields.