Marking territory

Dogs do it. Mark territory. So do humans. The methods differ. The objective is the same. To protect one’s turf by limiting entry. Nations use passports and visas, barbed wire and walls. Professions use qualifications. Unions sometimes use muscle power. The successful marking of territory is based on effectiveness of entry barriers. The caste system has been hugely successful given that entry is decided by the accident of birth. Many professions use qualifying exams, minimum qualifications and other means of limiting entry and marking territory.