Urbanization as a way of saving our planet from overpopulation

This paper explores whether biological mechanisms, induced by the overpopulation of a territory, exert essential influence on cities' growth, and whether the level of economic development of a country is significant, when biological mechanisms are in operation. To answer these questions, four hypotheses, based on the theoretical statements and empirical findings of ethology and demography, are formed. The results of regression analysis of statistical data on national level, applied to test these hypothesis, show that that biological factors should be considered as one of the determinants of cities' growth, but a complex analysis of factors of urban development is needed. The biological mechanisms of population reduction play a significant role in the least and less developed countries: with per capita GDP growth the concentration of population in big cities increases. Total fertility rate varies significantly in these countries, but with population growth it gradually decreases. In more developed countries with high per capita GDP level less than 60% of people live in cities with the population of 1 million inhabitants or more, and a total fertility rate stabilizes there at a simple reproduction level of ca. 2,0 births per woman.