section_path: Theories of motivation/Demographic/Malthusian
section_name: Malthusian
paragraph_text: Malthusian
  
  Malthusian theories see expanding population and scarce resources as a source of violent conflict. Pope Urban II in 1095, on the eve of the First Crusade, advocating Crusade as a solution to European overpopulation, said:
  
  For this land which you now inhabit, shut in on all sides by the sea and the mountain peaks, is too narrow for your large population; it scarcely furnishes food enough for its cultivators. Hence it is that you murder and devour one another, that you wage wars, and that many among you perish in civil strife. Let hatred, therefore, depart from among you; let your quarrels end. Enter upon the road to the Holy Sepulchre; wrest that land from a wicked race, and subject it to yourselves.
  
  This is one of the earliest expressions of what has come to be called the Malthusian theory of war, in which wars are caused by expanding populations and limited resources. Thomas Malthus (1766–1834) wrote that populations always increase until they are limited by war, disease, or famine. The violent herder–farmer conflicts in Nigeria, Mali, Sudan and other countries in the Sahel region have been exacerbated by land degradation and population growth.