The approach outlined in the present paper is based on observations made with African languages. Although the 1000-odd African languages display a remarkable extent of structural variation, there are certain structures that do not seem to occur in Africa. Thus, to our knowledge, an African language having anything that could be called an ergative case or a numeral classifier system has not been discovered so far. It may turn out that our approach can, in a modified form, be made applicable to languages outside Africa. This , however, is a possibility that has not been considered here. The present approach is based essentially on diachronic findings in that it uses observations on language evolution in order to account for structural differences between languages. Thus, it has double potential: apart from describing and explaining typological diversity it can also be material to reconstructing language history
