As such, in every society stratification based upon birth gets supplemented by stratification based upon earnings.
No society can claim that it had never assigned any status based upon birth. The only thing is that in some societies the basis of birth enjoys primary importance and the achievement basis enjoys relatively lesser importance, while in others the reverse of it is also true. For example, in a democratic society people enjoy equal rights and opportunities and any person can occupy any public office by contesting elections.
The statuses of persons in industrialized and developed societies now depend mostly upon earned positions. However, none can deny the fact that the family background always acts as a factor. For example, in India, the second generation of Indian leaders consists mostly of persons belonging to political families and even the traditional princely families.
Even in a developed society like the American society where merit and achievements constitute a basis for the grant of status, some importance is always given to the birth factor.
People in America still stand stratified into Whites and Negroes. As such, social stratification is always simultaneously based upon birth and achievements. The only difference is, that in some societies the basis of birth enjoys more importance while in others the merit and achievements enjoy more importance.