Farming systems have to evolve in order to face increasing uncertainty in their environment. In this review we analyse evolutions of farming systems over the long term as a double co-evolution : co-evolution of the farming system and its environment, and co-evolution of the farmer and his biotechnical system (farmer activity). We review literature from the livestock and crop sciences, and we deepen our analyse with some literature from management sciences, ergonomics, professional didactics that were cited or significantly related to long term approaches to crop or livestock farming systems. Learning is usually cited as an intersting evolution process. In agronomy, farmer activity has been modelled through the model of action, and the model of behaviour for action : these models respectively represent farmers' actions as planed on the one hand and as partly planed and partly emerging while they are happening on the other hand. Those representations are built according to a stalbe professional norm of the evolving farming systems that doesn't allow any important shift in the farming system over the long term. Representing evolutions of farming systems that the last over the long term requires integrating learning with farmer activity