The demographic transition model seeks to explain the transformation of countries from having high birth and death rates to low birth and death rates. In developed countries this transition began in the eighteenth century and continues today. Less developed countries began the transition later and are still in the midst of earlier stages of the model.
As with all models, the demographic transition model has its problems. The model does not provide "guidelines" as to how long it takes a country to get from Stage I to III. Western European countries took centuries through some rapidly developing countries like the Economic Tigers are transforming in mere decades. The model also does not predict that all countries will reach Stage III and have stable low birth and death rates. There are factors such as religion that keep some countries' birth rate from dropping.
Thomas Malthus warned that unchecked population would lead to famine, disease, and conflict. It seems as though farmers have managed to overcome short water supplies and depleted croplands to feed an almost doubled world population. Researchers warn though that the population is on a steady rise and sees signs that the scenario predicted by Malthus will come true. Countries such as Haiti, North Korea, Malawi, and Rwanda which are used to increasing birth and death rates are beginning to experience lower birth rates and higher death rates.
.
BR DR BR DR.
(1995) (2002).
Haiti 35 12 33 15.
North Korea 23 6 18 10.
Malawi 47 20 46 22 Rwanda 40 17 42 21.
Higher Death rates in these countries is caused by numerous factors. With the growth in food production and population comes a decrease in water supply because it takes water to irrigate crops. Water from the Nile is so heavily depleted that little actually reaches the Mediterranean Sea.