The extension services belong to the Agricultural Knowledge System (AKS), that comprehends research and higher education in agriculture too. The services transmit the information on technical and managerial innovations to farmers and translate the innovation's demand into research and higher education, thus playing a double 'pivot' function: one inside the organization of farming and rural systems and other in the natural and social systems' co-evolution. We must make an effort to better link natural and social sciences in order to explain the Gaia hypothesis' evolutionary games. The services organization empirically shows an evolutionary feature, according to technological change and social evolution, as well as it is described by the development stages. Developed countries are questioning if the AKS is still important in affluent societies: the OECD conference in Paris in 1995 replied that food quality and safety, rural world mantainence, environment preservation and sustainability of economic development are all the goals that still need a strong AKS in developed countries too. In the third millennium the extension services will have the task to master social and natural co-evolution so that the speed of the economic development does not destroy the capability of the natural and social systems' evolution to live side by side.