The contrasting ecological zonation found in low-latitude mountain regions worldwide has resulted in distinctive social configurations that appear to reduce risk, broaden the selection of products available in a given zone, and provide opportunities for strategic advancement by particular individuals or groups. These configurations have been investigated in two broad sets by Andeanists. First, there are a number of scholars who address vertical complementarity as a general process that is comparable with other mountain regions of the world. Second, there is a particular configuration known as "Vertical archipelagos" first described by John Murra (1972) that has been widely discussed in the Andean literature.