The Black Death, or Black Plague, was a devastating pandemic that began in south-western Asia and spread to Europe by the late 1340s, where it got the name Black Death. It killed between a third and two-thirds of Europe's population and, including Middle Eastern lands, India and China, killed at least 75 million people. The same disease is thought to have returned to Europe every generation with varying degrees of intensity and fatality until the 1700s. Notable later outbreaks include the Italian Plague of 1629-1631, the Great Plague of London (1665--1666), the Great Plague of Vienna (1679), the Great Plague of Marseille in 1720--1722 and the 1771 plague in Moscow. There is some controversy over the identity of the disease, but in its virulent form seems to have disappeared from Europe in the 18th century.
The Black Death had a drastic effect on Europe's population, irrevocably changing Europe's social structure. It was a serious blow to the Roman Catholic Church, Europe's predominant religious institution at the time, and resulted in widespread persecution of minorities such as Jews, Muslims, foreigners, beggars and lepers. The uncertainty of daily survival created a general mood of morbidity influencing people to live for the moment, as illustrated by Giovanni Boccaccio in The Decameron (1353).
The initial fourteenth-century European event was called the "Great Mortality" by contemporary writers and, with later outbreaks, became known as the 'Black Death'. It has been popularly thought that the name came from a striking symptom of the disease, called acral necrosis, in which sufferers' skin would blacken due to subdermal haemorrhages. However, the term refers in fact to the figurative sense of "black" (glum, lugubrious or dreadful).
Because the Black Death was, according to historical accounts, characterised by buboes (swellings in the groin), like the late 19th century Asian Bubonic plague, scientists and historians assumed at the beginning of the twentieth century that the Black Death was an outbreak of the same disease, caused by the bacterium Yersinia pestis and spread by fleas with the help of animals like the black rat (Rattus rattus). However, buboes are a feature of other diseases as well and this view is now widely questioned.
Renewed religious fervour and fanaticism bloomed in the wake of Black Death. This spelled trouble for minority populations of all sorts, as Christians targeted "various groups such as Jews, friars, foreigners, beggars, pilgrims, Muslims",and lepers, thinking that they were somehow to blame for the crisis.
Lepers, and other individuals with skin diseases such as acne or psoriasis, were singled out and exterminated throughout Europe. Anyone with leprosy was believed to show an outward sign of a defect of the soul.
Traditionally a lightning rod for Christian anger and unease, Jews were charged with having provoked the Plague through their unbelief and sinfulness. Differences in cultural and lifestyle practices between Jews and Christians also led to persecution. Because Jews had a religious obligation to be clean, they did not use water from public wells. Thus Jews were suspected of causing the plague by deliberately poisoning wells. Typically, comparatively fewer Jews died from the Black Death, in part due to rabbinical laws that promoted habits that were generally cleaner than that of a typical medieval villager. Jews were also socially isolated, often living in Jewish ghettos. This isolation may have caused differences in mortality rates which raised suspicions of people who had no concept of bacterial transmission.
Christian mobs attacked Jewish settlements across Europe; by 1351, sixty major and 150 smaller Jewish communities had been destroyed, and more than 350 separate massacres had occurred. This persecution reflected more than religious hatred. In many places, attacking Jews was a way to criticize the monarchs who protected them (Jews were under the protection of the king, and often called the "royal treasure"), and monarchic fiscal policies, which were often administered by Jews. An important legacy of the Black Death was to cause the eastward movement of what was left of north European Jewry to Poland and Russia, where it remained until the twentieth century.
In Mecca, the disease was blamed on non-believers who had entered the city.
The Black Death led to cynicism toward religious officials who could not keep their promises of curing plague victims and banishing the disease. No one, the Church included, was able to cure or accurately explain the reasons for the plague outbreaks. One theory of transmission was that it spread through air, and was referred to as miasma, or 'bad air'. This increased doubt in the clergy's abilities. Extreme alienation with the Church culminated in either support for different religious groups such as the flagellants, which grew tremendously during the opening years of the Black Death, or to an increase in interest for more secular alternatives to problems facing European society and an increase of secular politicians.
The Black Death hit the monasteries very hard because of their close quarters with the sick, who had come to the monasteries seeking aid, so that there was a severe shortage of clergy after the epidemic cycle. This resulted in a mass influx of new clergy members, most of whom did not share the life-long convictions and experiences of the veterans they replaced. This resulted in abuses by the clergy in years afterwards and a further deterioration of the position of the Church in the eyes of the people.
After 1350, European culture in general turned very morbid. The general mood was one of pessimism, and the art turned dark with representations of death. The Dies Irae was created in this period as was the popular poem La Danse Macabre and the instructive and popular Ars moriendi ("the art of dying"). See also The Decameron.
The practice of alchemy as medicine, previously considered the norm for most doctors, slowly began to wane as the citizenry began to realize that it seldom affected the progress of the epidemic and that some of the potions and "cures" used by many alchemists only served to worsen the condition of the sick. Liquor, originally made by alchemists, was commonly applied as a remedy for the Black Death, and, as a result, the consumption of liquor in Europe rose dramatically after the plague.
In 2006 a scientific study by Dr Thomas van Hoof of Utrecht University suggests that the Black Death contributed to the Little Ice Age. Pollen and leaf data, collected from lake-bed sediments in the southeast Netherlands, supports the idea that millions of trees sprang up on abandoned farmland soaking up carbon dioxide from the atmosphere and thus cooling the planet.
A theory put forth by Stephen O'Brien says the Black Death is likely responsible, through natural selection, for the high frequency of the CCR5-?32 genetic defect in people of European descent. The gene affects T cell function and provides protection against HIV, smallpox, and possibly plague, though for the latter, no explanation as to how it would do that exists