Sentence:  Already Mexico City is a warning to other developing countries where centralized government, a high birth rate, neglect of agriculture and the rush to industrialize have combined to encourage migration to the cities. Twenty percent of the country's population lives here, and the term urban <WSD>macrocephaly</WSD> has been coined to describe the phenomenon. 
Meaning of the word marked with <WSD> tags:  The excessive concentration of population and development in a single centre, to the detriment of other areas.