(a)The main features of the Malthusian theory are:
(i) That population was growing at a geometrical progression while food production was growing at arithmetical progression.
(ii) That there is a tendency for all living things to grow beyond the food available to them.
(iii) Unless population increase is matched with means of subsistence, negative and positive checks will come into force.
(iv) That population is essentially limited by the means of subsistence.
(b) The theory has become irrelevant due to the following facts:
(i) The development in technical knowledge and mechanization of agriculture to increase food supply.
(ii) Changes in social attitudes as regards family size.
(iii) Increased efficiency in the transportation system enables more materials to be provided to areas that needed them.
(iv) The industrial revolution also changed the idea of land as a fixed factor of production.
(v) Opening of new colonies which provided the needed land
(vi) The interdependency of nations as a result of international trade.