The plains of Sumatra and Kalimantan (our study area) were scarcely inhabited at the turn of the 19th century, population density inferior to 4 inhabitants/km2, mainly relying on shifting cultivation of upland rice. The introduction of rubber by private dutch estates in the 1910's triggered a radical change in the landscape evolution but not in farmers practices, at least at the beginning. As estates adopted monoculture right from the beginning, trying to maximize rubber production, farmers saw and exploited immediately the possibility of growing rubber on a very extensive way by enriching their fallows (belukar in Indonesian) with unselected rubber seedlings that was available and free. Planting rubber during, or after, upland rice was a very marginal supplementary amount of work, with no risks and more important: no cost. Rubber used to grow with the secondary forest in a complex agroforestry system called "jungle rubber". Productivity was sufficient to raise a very incentive income however rubber taping occurs with a delay compared to rubber monoculture in estates. The advantages of jungle rubber are clear: no cost, no labour required for maintenance during immature period, income diversification with fruits, rattan, timber and other NTFP (non timber forest products) from the agroforest. Indirect benefits are environmental with soil conservation and rehabilitation of degraded lands. Estates began to raise their own research programme in the 1920's leading to the adoption of several important innovations, fertilization, weeding level, exploitation systems among them improved planting material, the clones, has been the most important in terms of yield. Meanwhile farmers began to produce several innovations, with no cost, called "endogenous innovations" such as planting in lines, a minimum weeding (once a year) ... mainly through the improvement of some rubber farming practices. At that stage as the aim was definitely to establish a rubber system minimizing capital