Although it is customary to think of human population as increasing continuously without declines or fluctuations, population growth has not been a steady march. for example, great declines occurred during the time of the black death, during the fourteenth century. entire towns were abandoned, production of food declined, and in england, one-third of the population died within a single decade. (daniel b. botkin and edward a keller, environmental science)

The human population has experienced many fluctuations throughout the history of man kind. There has been periods of relative stagnation, periods of growth, and periods of decline. The periods of relative stagnation have appeared before the civilizations started to develop to the period of the middle ages. Even though there were many children born, the mortality rate of them was very high, and also the life expectancy was much shorter, so the population was keeping pretty much the same number, with only slow very small increase. The declines of populations have usually occurred during the periods of pandemic diseases, and during periods of greater prolonged wars. The most noticable increase of population has been after the World War II when appeared the so called ''baby boom''. Ever since then there's a constant population growth, but slowly it is decreasing. This is due to the very low fertility rate in North America, Europe, and East Asia, but the general population is still growing because of the big fertility rate in Africa and South Asia. It is expected that very soon the total population will reach the number of 10 billion.

aristocracy, timocracy, oligarchy, democracy, theocracy and tyranny

explanation:

because the early people found out about it.