ABSTRACT
In Karl Marx's view, hunger was caused by exploitation rather than overpopulation. This aspect of Marx's theory referred to the fact that humans are social, not solitary animals. While humans have increased in number, however, they have remained strongly dependent on organic substances that originate from biological processes. Biomass can become available to humans in two forms. Living biomass has been produced by nature. Fossil biomass consists of hydrocarbons such as coal, oil or natural gas, which have been formed out of living biomass over geological time. The evolution of living biomass production systems interacted with the evolution of industries and trade. As the German economist Heinrich von Thunen already observed in the 19th century, the emergence of urban centres caused a spatial differentiation in agricultural production. Many farmer societies had evolved where central rulers had curtailed the power of the aristocracy or where farmers had resisted local power holders who wanted to live on their labour.
