World population reached seven billion

Population size is now growing rapidly. However, the center of growth in Europe and North America has shifted to developing countries in Southeast Asia and Africa. Forecast for the future depends on how quickly these countries will be reduced fertility. Taken at different values ​​of fertility rates (number of children born for the life of a mother) it is expected that by 2100 the Earth will be from 6.1 to 15.8 billion.

In 2011, the total number of people on the planet has reached $ 7 billion. This in some ways a symbolic figure was the reason for the appearance in the journal Science a number of publications that analyze the current situation and projections for the future.

During at least 2.4 million years, representatives of the genus Homo were gatherers, but at the beginning of the Holocene at several different places (in the Eastern Mediterranean, in New Guinea, Ethiopia, northern and southern China, in eastern North America and in South America) began to appear primitive agriculture. Chronologically, this happened in a fairly wide time interval - from 11 500 to 3,500 years ago. Most likely, the number of Homo sapiens at the dawn of agriculture amounted to about 6 million. Over the past since 11 thousand years it has increased again in 1200!

The transition from the era of hunting and gathering to agriculture is called “Neolithic Revolution.” Its main result - a significant increase in the number of people who could support themselves with the same area. Thus, if the gathering and hunting to support the existence of not more than 0.05 persons per 1 km2, the modern agriculture can be from 1 km2 of cultivated land, ensure food 54 people, and by 2050 this figure will probably 70-80 people.

The fact that the number of people began to grow rapidly after the “Neolithic Revolution”, shows the analysis of fossil remains of ancient tombs. Among the discovered skeletons sharp increase in the proportion of children and adolescents (5 to 19 years), that specifically draws the attention of Jean-Pierre Bocquet-Appel (Jean-Pierre Bocquet-Appel) from the National Center for Scientific Research in France. Such a shift in the age structure of ancient human populations indicates a significant increase in fertility. Although mortality was still high, the population began to grow still faster. Marked change in the ratio of births and deaths are called “Neolithic demographic transition.” To some extent it is the mirror of “the modern demographic transition”, which is characterized by a rapid decrease in mortality (especially infant mortality), while maintaining a high birth rate (which is only then begin to decline).

11 September 2011

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