Following the example of Tiffen et al. on Machakos, Kenya, new macro-based evidence was collected in Machakos, the neighbouring Kitui district and in Benin, Cameroon and the Philippines, to assess the factors à la Boserup, inducing transitions towards sustainable land management, such as terracing, stone bands etc. We find that relative scarcity of land can be seen to induce technical changes, in the sense of Hayami & Ruttan, that correspond to the new relative scarcity, making higher man-land ratios the optimal choice.