malthusian theory

Malthusian Population Trap (Malthusian Theory on Population Growth and Economic Development) Reverend Thomas Malthus published An Essay on the Principle of Population in 1798 which argued that population increases geometrically ( i.e. 1, 2, 4, 8, 16..) doubling every 30 to 40 years while food supplies expand only arithmatically (becuase of diminishing returns to fixed factors such as land). This means that each person will have less land to work and therefore per capita food production will decline. Malthus argued that the only way to avoid this is to limit the number of children per family (what he calls negative checks on population). If negative checks do not exist, he continued, then the population will be checked by famines, epidemics or wars (what he calls these positive checks on population).
The development of agricultural engineering has reduced the amount of land required to feed one person from 20,000 square metres to 2,000 square metres. This was brought about by inovations such as:
Mechanical harvesters. (late 1800's)
The Haber-Bosch process (early 1900's) in which atmospheric nitrogen was fixed and used to manufacture ammonia to provide unlimited supplies of nitrogenous fertilizer.
Hybrid varieties of crops (early 1900's).
The 'Green Revolution' began in 1948 in Mexico and really exploded in India in the 1960s. It involved bringing new, hi tech agricultural techniques to underdeveloped countries, resulting in a big spurt in food production.
Future:
Grain production per hectare has risen at only 1 percent since 1990 after rising at twice that rate for the previous 40 years.
The four largest countries, China, India, USA and Indonesia all have population growth rates of less than 1%. Number 5 and 6 (Pakistan and Nigeria) have growth rates of 1.4 and 1.7% respectively.
The world population is growing at 0.8%. If agricultural production growth continues to decline (climate change may contribute to it), we may still see Malthus' prediction come true.