the victory of a 72-year-old former general , muhammadu buhari , in the nigerian elections represents a moment of maturity in west african politics .
buhari , who some 30 years ago was nigeria 's harsh military leader , could be a disaster .
for too long , nigeria 's poor have been victims of their country 's enormous wealth .
but stability was contingent upon oil remaining at $ 110 a barrel , and in recent months the price has collapsed to below $ history .