This is an important and timely paper. Bourn and Wint provide highly generalisable, empirical evidence that the concentrations of livestock across the Sahel and the adjacent agro-ecological zones are closely related to cropping intensity and population density. This should make it easier to  understand development conundrums such as why grazing reserves, set aside for the exclusive use of pastoralists, have had so little acceptance by the intended beneficiaries. Clearly the pastoralists do not want to be far away from farmers' fields and markets. The correlation between cultivation and livestock suggests that livestock and crop development can and do go hand-in-hand. More importantly, the further evidence Bourn and Wint provide from Nigeria, on the widespread use of animal traction and livestock fattening, supports the belief that population density and crop intensification are not only related to increased livestock numbers, but also to livestock intensification in mixed farming systems.