The world and humanity have developed during the past hundred years as never before. The population of humans living on the planet Earth has doubled over the past five decades and it is currently estimated to be 6,9 billion, moreover it is projected to reach at least 9 billion by 2050. Despite the fact that the human race has achieved unbelievable successes, there is still the most important global issue: sustainability of population growth, that remains questionable, even overlooked, out of the interest of so - called western society. In my opinion, the reason why it is so, is quite simple. People let influence their life by the motto: “Let's live for the present” and forget about the responsibility for the next generations which they bear on their shoulders, in addition, they usually focus only on the everyday life instead of paying enough attention to the essential facts and information.

In order to ensure long lasting sustainable growth and survival of human race and to avoid or even warn about the danger of the worst scenario, the humanity has come up with 2 opposing population theories about what happens when there are not enough resources for the population:

1. Malthus's Essay on the Principle of Population - 1798
2. The Conditions of Agricultural Growth: The Economics of Agrarian Change under Population Pressure - 1965

1. Malthus's Essay on the Principle of Population

In 1798 British scholar Thomas Malthus published his pessimistic revolutionary views on the effect of population on food supply. His theory has two basic principles:
- population grows at a geometric rate i.e. 1, 2, 4, 16, 32, etc.,
- food production increases at an arithmetic rate i.e. 1, 2, 3, 4, etc.

The consequence of these two principles is that eventually, population will exceed the capacity of agriculture to support the new population numbers. Population would rise until a limit to growth was reached. Further growth would be limited when:
-positive checks - famine, war, disease (increasing the mortality rate and reducing life expectancy),
-negative checks (decreased birth rate) - postponement of marriage (lowering of fertility rate), proposed only for the working and poor classes.

On the other hand, Malthus's theory has it's minuses as well. His predictions have not proved to be accurate, it is because he did not consider the facts such as: technological improvements (genetically modified crops which means that the efficiency of land has increased), the increased amount of cropland due to irrigation.