2.Human population History
According to Cunningham (2000) for a most of human history, population growth was very slow. Many studies of hunting and gathering societies show that the total world population wasn't more than a few million people before innovation of agriculture and the domestication of animals around 10,000 years ago. The bigger and more secure food supply results in human population to growth, reaching perhaps 50 million people (b.c). Moreover, some historical evidence and description suggest that only about 300 million people were living at the time of Christ. During the Middle Age, many diseases and wars held world population. The main reasons were lack of hygiene and life condition and as consequence made human life short and uncertain. During the most destructive disease, plaque that took many lives between 1348 and 1350, it is estimated that at least one-third of European population perished. At the end of last great plague, there ware about 600 million people on the earth. After 1600 human population increase rapidly and in 1800 reach one billion. It took a century and a half more to reach the 1950 figure of 2.5 billion. But in a post World War II period the populations was doubled in less than forty years, and exceed 5 billion. By the year 2000 world population had passed six billion. Today we are facing with a human population explosion, in other words every second approximately four or five children are born somewhere on the earth and in the same second two other people die. …
