World population

world population commonly refers to the total number of living humans on Earth at a given time. As of 13 August 2009, the Earth's population is estimated by the United States Census Bureau to be 6.777 billion.[1] The world population has been growing continuously since the end of the Black Death around 1400. There were also short term falls at other times due to plague, for example in the mid 17th century (see graph)

The fastest rates of world population growth (above 1.8%) were seen briefly during the 1950s then for a longer period during the 1960s and 1970s (see graph). According to population projections, world population will continue to grow until around 2050. The 2008 rate of growth has almost halved since its peak of 2.2% per year, which was reached in 1963. World births have levelled off at about 134-million-per-year, since their peak at 163-million in the late 1990s, and are expected to remain constant. However, deaths are only around 57 million per year, and are expected to increase to 90 million by the year 2050. Since births outnumber deaths,

A dramatic population bottleneck is theorized for the period around 70,000 BCE (see Toba catastrophe theory). After this time and until the development of agriculture, it is estimated that the world population stabilized at about one million people whose subsistence entailed hunting and foraging, a lifestyle that by its nature ensured a low population density. It is estimated that over 55 million people lived in the combined eastern and western Roman Empire (300–400 AD).[5] The Plague of Justinian caused Europe's population to drop by around 50% between 541 and the 700s.[6] The Black Death pandemic in the 14th century may have reduced the world's population from an estimated 450 million to between 350 and 375 million in 1400.