Antiquity and Middle Ages
A dramatic population bottleneck is theorized for the period around 70,000 BC (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. The total world population probably never exceeded 15 million inhabitants before the invention of agriculture. By contrast, it is estimated that more than 55 million people lived in the combined eastern and western Roman Empire (AD 300–400).
The Plague of Justinian caused Europe's population to drop by around 50% between 541 and the 8th century. The population of Europe was more than 70 million in 1340. 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. It took roughly 200 years for Europe's population to regain its 1340 level. China experienced a population decline from an estimated 123 million around 1200 to an estimated 65 million in 1393, which was presumably due to a combination of Mongol invasions and plague. William McNeill clearly states that China's population decline is better explained by bubonic plague than by Mongol ferocity.
At the founding of the Ming Dynasty in 1368, China's population was reported to be close to 60 million, and toward the end of the dynasty in 1644 it might have approached 150 million. England's population reached an estimated 5.6 million in 1650, up from an estimated 2.6 million in 1500. New crops that had come to Asia and Europe from the Americas via the Spanish colonizers in the 16th century contributed to the population growth. Since being introduced by Portuguese traders in the 16th century,maize and manioc have replaced traditional African crops as the continent’s most important staple food crops. Alfred W. Crosby speculated that increased production of maize, manioc, and other American crops "...enabled the slave traders [who] drew many, perhaps most, of their cargoes from the rain forest areas, precisely those areas where American crops enabled heavier settlement than before."
The population of the Americas in 1500 may have been between 50 and 100 million. The pre-Columbian North American population probably numbered somewhere between 2 million and 18 million. Encounters between European explorers and populations in the rest of the world often introduced local epidemics of extraordinary virulence. Archaeological evidence indicates that the death of around 90% of the Native American population of the New World was caused by Old World diseases such as smallpox, measles, and influenza. Over the centuries, the Europeans had developed high degrees of immunity to these diseases, while the indigenous peoples had no such immunity.
Human population control
Human population control is the practice of artificially altering the rate of growth of a human population.
Historically, human population control has been implemented by limiting the population's birth rate, by contraception or by government mandate, and has been undertaken as a response to factors including high or increasing levels of poverty, environmental concerns, religious reasons, and overpopulation.
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