Black Death Evolution Consequences Alternative Explanations

The Black Death (also Bubonic plague, and more recently The Black Plague) was a devastating epidemic in Europe in the mid 14th century (1347-50). It used to be thought to have killed about a third of the population, but recent scholarship now tends towards an estimate of nearer half the population irrespective of age or gender. Although the matter is in dispute, many scholars have generally believed that the Black Death was an outbreak of bubonic plague, a dreaded disease that has spread in pandemic form several times through history. Again recent scholarship is moving away from this view and preferring instead explanations that see parallels with diseases like Ebola.

The traditional view is that the 14th century plague was caused by the bacterium Yersinia pestis which is spread by fleas with the help of animals like the black rat (Rattus rattus) — what we would call today the sewer rat. The possibility for a deadly human illness to be carried by non-human species is due to the many differences between human and non-human anatomy and physiology. Comparative anatomy studies the evolutionThis article is about biological evolution. For other possible meanings, see Evolution (disambiguation). Evolution generally refers to any process of change over time. However, in the context of the life sciences, evolution is a change in the genetic make of the complex morphological systems which make this possible.

1 Evolution

It is not entirely clear where the major epidemic of the 14th century started, perhaps somewhere around the northern parts of IndiaThe Republic of India is a large multicultural country in South Asia, with a population of over one billion. The Indian economy is the fourth largest in the world, in terms of purchasing power parity, and is the world's second-fastest growing economy., but more likely in the steppeIn physical geography, steppe (from Russian , step is a plain without trees (apart from those near rivers and lakes); it is similar to a prairie, although a prairie is generally reckoned as being dominated by tall grasses, while short grasses are said tos of central AsiaThe continent of Asia is defined by subtracting Europe and Africa from the great land mass of Africa-Eurasia. The boundaries are vague, especially between Asia and Europe: Asia and Africa meet somewhere near the Suez Canal. The boundary between Asia and E, from where it was carried west by Mongol armies. The plague was imported to Europe by the way of the Crimea, where the Genoese colony Kaffa ( Feodosiya) was besieged by the Mongols. History says that the Mongols catapulted their infected corpses into the city. The refugees from Kaffa then took the plague along to Messina, Genoa and Venice, around the turn of 1347/ 1348. Some ships didn't have anyone alive when they reached their port. From Italy the disease spread clockwise around Europe, hitting France, Spain, England (in June 1348) and the rest of Britain, Germany, Scandinavia from 1348 to 1350, and finally north-western Russia around 1351. The parts of Europe largely spared by the plague included Kingdom of Poland and parts of Belgium and Netherlands. In 1896, a scientist named Alexandre Yersin isolated the plague bacterium and determined that it was spread by rat fleas (Xenopsylla cheopis) and a certain species of rat found in the Gobi Desert.

2 Consequences

Inspired by Black Death, Danse Macabre is an allegory on the universality of death and a common painting motive in the late-medieval The Black Death followed upon a recession in the European economy that had been under way since the beginning of the century, economic historians like Fernand Braudel have concluded, an economy that was disrupted by the blocking of the Silk Road, the decline in the Champagne fairs, the stiffening of Islamic resistance to European intrusions, the great recession of the 14th century that Barbara Tuchman has described in A Distant Mirror. The Black Death hit the culture of towns and cities disproportionately hard: rural areas, for example in of Eastern Poland and Lithuania, were so isolated that the plague made little progress.

Information about the death toll varies widely from source to source, but it is estimated that about a third of the population of Europe died from the outbreak in the mid- 1300s. Approximately 25 million deaths occurred in Europe alone, with many others occurring in Africa and Asia. Some villages were deserted, the few survivors fleeing and spreading the disease further. There is some speculation that the Black Death fatally weakened the Mongol Empire by decimating the Mongols and their conquered peoples, leaving it to fragment and ultimately collapse.

The great population loss brought economic changes based on increased social mobility, as depopulation further eroded the peasants' already-weakened obligations to remain on their traditional holdings. In Western Europe, the sudden scarcity of cheap labor provided an incentive for innovation that broke the stagnation of the Dark Ages and, some argue, caused the Renaissance, despite the Renaissance occurring in some areas (such as Italy) before others. In Eastern Europe, by contrast, renewed stringency of laws tied the remaining peasant population more tightly to the land than before. However, also because of depopulation, the surviving Europeans became the biggest consumers of meat of any civilization before industrial agriculture.

As with other natural and man-made social disasters, renewed religious fervor and fanaticism bloomed in the wake of the Black death. In many parts of Europe, rumors circulated that the plague was caused by the deliberate poisoning of wells by Jews. Fierce pogroms frequently resulted in the death or banishment of most of the Jews in a town or city.

The reduction in the population of England led to the displacement of French by English. It has also been alleged (since 1961) that the Black Death inspired one of the most enduring nursery rhymes in the English language, Ring around a rosie, a pocket full of posies, / Ashes, ashes, we all fall down. However, this explanation is a literary interpretation without historical supporting evidence.

See also Danse macabre, Decameron, flagellant, pogrom.

3 Alternative explanations

Recently the scientists Susan Scott and Christopher Duncan from Liverpool University have proposed the theory that the Black Death might have been caused by an Ebola-like virus, not a bacterium. Their rationale is that this plague spread much faster and the incubation period was much longer than the plagues caused by Yersinia pestis. (A longer period of incubation will allow carriers of the infection to travel farther and infect more people than a shorter one. When the primary vector is humans, as opposed to birds, this is of great importance.) Studies of English church-records indicate an unusually long incubation period in excess of 30 days which could account for the rapid spread, topping at 5 km/day. It also took place in completely ratless areas like Iceland. It was transferred between humans (which happens rarely with Yersinia pestis), and some genes that determine immunity to Ebola-like viruses are much more widespread in Europe than in other parts of the world.

Another alternative explanation was proposed by Graham Twigg in his 1985 book The Black Death: A Biological Reappraisal.

In a similar vein, historian Norman F. Cantor , in his 2001 book In the Wake of the Plague, suggests the Black Death might have been a combination of pandemics including a form of anthrax, a cattle murrain. Included in the evidence he cites are reported disease symptoms not in keeping with the known effects of either bubonic or pneumonic plague; the discovery of anthrax spores in a plague pit in Scotland, and the fact that meat from infected cattle was known to have been sold in many rural English areas prior to the onset of the plague.

Rattus rattus, the black rat, was introduced from Asia to Europe by trade and shipping. An interesting hypothesis about the appearance, spread and disappearance of plague from Europe may be that the introduced black rat infection reservoir and its disease vector was subsequently displaced and succeeded by the bigger Norwegian or brown rat (Rattus norvegicus), not so prone to transmit the germ-bearing fleas to humans in large rat die-offs (see Appleby and Slack references below).

Moreover, what was previously considered to be final evidence for the Yersinia pestis theory, tooth pulp tissue taken from a 14th century plague cemetery in Montpellier containing Y. pestis DNA, was never confirmed in any other cemetery.

There are counter-arguments to this theory, however. Historical examples of pandemics of other diseases in populations not previously exposed, such as smallpox and tuberculosis amongst American Indians, show that because there is no inherited adaptation to the disease, its course in the first epidemic is faster and far more virulent than later epidemics amongst the descendants of survivors. The Middle East and Far East were affected equally badly (as the Rihla of Ibn Battuta testifies), so the prevalence of immunity genes specifically in Europeans is curious. Furthermore, the plague returned again and again and was regarded as the same disease through succeeding centuries into modern times when the Yersinia bacterium was identified.

In September 2003, a team of researchers from Oxford University revealed the surprising results of tests made on 121 teeth from 66 skeletons found in 14th century mass graves. The remains showed no genetic trace of Yersinia pestis, and the researchers suggest that the Montpellier study might have been flawed.

4 External links and references

Overview of the Black Death with eyewitness accounts
BBC news story on controversy over Black Death origins
Mark Derr, "New Theories Link black Death to Ebola-Like Virus", The New York Times, Science Section, October 2, 2001.
Examination of "Ring around the Rosy"'s relationship to the plague
Paul Slack “The Disappearance of the Plague: An Alternative View” Economic History Review 34, 3. 1981 469-476
Andrew B. Appleby “The Disappearance of the Plague: A Continuing Puzzle” Economic History Review 33, 2, 1980 161-173

European history Pandemic

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