On 1 January 2010 the population of the Earth was approximately 6.9 billion people. Mark 6 billion was completed in 1999. According to scientists, the level of 7 billion will be eliminated at the end of 2010.
Now how did the growth of the population of our planet:
|The end of the Paleolithic period (about 15 thousand years BC)||3 million|
|The late Neolithic (2 thousand years BC)||50 million|
|The beginning of our era||230 million|
|The end of the 1st Millennium A.D.||275 million|
The forecast for 2050
Graphically it looks like this:
As can be seen from this graph, somewhere 8-10 thousand years ago there was a jump in the growth rate of the number of people on the planet. And in the XVIII century there was another pull, the population growth rate was much higher than before. What explains these races?
The main factor that determines the population on Earth is human activities. Up to 10 thousand BC people were mostly engaged in gathering and hunting. The population then was about 10-15 million people (the number of large modern cities, such as new York or Moscow). Many scientists believe that the primitive people was very high fertility - 35-55 people in the year 1000 and the same high mortality. During his life, the woman had about 5-10 children, many of whom died in childhood. The average life expectancy was only 30 years.
About 10 thousand years BC was an important event - the agricultural revolution: people have domesticated some animals and learned to grow some plants. The man moved to the production of products. And it is possible to increase consumption, and made possible a higher population density than in the aggregate economy. Happened the first surge of population, and the population gradually increased several times - about 50 million.
Several thousand years on Earth there was a relatively stable population size. People could not control the weather, and therefore population growth in the productive years were destroyed by famine in the lean years. The population was often reduced as a result of wars, epidemics and famine.
In the XVIII century there was another major event - the industrial revolution: manual labor was gradually supplanted by the work of machines. It was possible to produce much more benefits with lower costs. In addition, there was a leap in the development of medicine, which helped to reduce mortality from many diseases. The world's population has been increasing rapidly - there has been a population explosion.
Before the 70-ies of XX century the population grew very quickly (as mathematicians would say - according to the hyperbolic law, that is, when the growth rate of population is proportional to the square of its number). Then the rate of population growth has decreased. Now the population growth is happening in other law - logistics:
We make such a model, in which population growth is approximately equal to the death rate, and the total population remains stable. The reason for this phenomenon scientists believe the fertility decline that occurred first in economically developed countries, but now in the Third world countries. Parents in the modern world prefer "high quality" to grow 1-2 children than to pump a lot of children. The death rate in modern world, too, reduced: thanks to the development of medicine increase life expectancy. The transition from high fertility and mortality to low has called demographic transition.
Now we can confidently say that most people in the twenty-first century will live in cities. The average life expectancy of close to 90 years, and the maximum, it will probably be for 130 years. Older people on the planet will be two times more than children.
By the way...
• How many people can feed the Earth? There are many opinions, from the most pessimistic (1 billion or less) to very optimistic. Academician Sergey Kapitsa believes that "under reasonable assumptions, the Earth can sustain for a long time up to 15 - 25 billion people."
• ...Until you read this page (20 minutes, no more, huh?) on Earth was added 4.5 thousand people. This is a whole village!