title: Stagflation

text: Both explanations are offered in analyses of the 1970s stagflation in the West. It began with a large rise in oil prices, but then continued as central banks used excessively stimulative monetary policy to counteract the resulting recession, thereby causing a price/wage spiral.


title: Stagflation

text: Increased requirements on skill (education and experience) on work force, for example because of increased technical complexity, can cause shortage on skilled employees and rising salaries for them, at the same time as uneducated work tasks have in part moved to low salary countries such as in Asia, causing high unemployment.


title: Stagflation

text: Up to the 1960s, many Keynesian economists ignored the possibility of stagflation, because historical experience suggested that high unemployment was typically associated with low inflation, and vice versa (this relationship is called the Phillips curve). The idea was that high demand for goods drives up prices, and also encourages firms to hire more; and likewise, high employment raises demand. However, in the 1970s and 1980s, when stagflation occurred, it became obvious that the relationship between inflation and employment levels was not necessarily stable: that is, the Phillips relationship could shift. Macroeconomists became more sceptical of Keynesian theories, and Keynesians themselves reconsidered their ideas in search of an explanation for stagflation.


title: Stagflation

text: The explanation for the shift of the Phillips curve was initially provided by the monetarist economist Milton Friedman, and also by Edmund Phelps. Both argued that when workers and firms begin to expect more inflation, the Phillips curve shifts up (meaning that more inflation occurs at any given level of unemployment). In particular, they suggested that if inflation lasted for several years, workers and firms would start to take it into account during wage negotiations, causing workers' wages and firms' costs to rise more quickly, thus further increasing inflation. While this idea was a severe criticism of early Keynesian theories, it was gradually accepted by most Keynesians, and has been incorporated into New Keynesian economic models.


title: Stagflation

text: Neo-Keynesian theory distinguished two distinct kinds of inflation: demand-pull (caused by shifts of the aggregate demand curve) and cost-push (caused by shifts of the aggregate supply curve). Stagflation, in this view, is caused by cost-push inflation. Cost-push inflation occurs when some force or condition increases the costs of production. This could be caused by government policies (such as taxes) or from purely external factors such as a shortage of natural resources or an act of war.


title: Stagflation

text: Contemporary Keynesian analyses argue that stagflation can be understood by distinguishing factors that affect aggregate demand from those that affect aggregate supply. While monetary and fiscal policy can be used to stabilise the economy in the face of aggregate demand fluctuations, they are not very useful in confronting aggregate supply fluctuations. In particular, an adverse shock to aggregate supply, such as an increase in oil prices, can give rise to stagflation.


title: Stagflation

text: Supply theories are based on the neo-Keynesian cost-push model and attribute stagflation to significant disruptions to the supply side of the supply-demand market equation, such as when there is a sudden real or relative scarcity of key commodities, natural resources, or natural capital needed to produce goods and services. In this view, stagflation is thought to occur when there is an adverse supply shock (for example, a sudden increase in the price of oil or a new tax) that causes a subsequent jump in the "cost" of goods and services (often at the wholesale level). In technical terms, this results in contraction or negative shift in an economy's aggregate supply curve.


title: Stagflation

text: In the resource scarcity scenario (Zinam 1982), stagflation results when economic growth is inhibited by a restricted supply of raw materials. That is, when the actual or relative supply of basic materials (fossil fuels (energy), minerals, agricultural land in production, timber, etc.) decreases and/or cannot be increased fast enough in response to rising or continuing demand. The resource shortage may be a real physical shortage, or a relative scarcity due to factors such as taxes or bad monetary policy influencing the "cost" or availability of raw materials. This is consistent with the cost-push inflation factors in neo-Keynesian theory (above). The way this plays out is that after supply shock occurs, the economy first tries to maintain momentum. That is, consumers and businesses begin paying higher prices to maintain their level of demand. The central bank may exacerbate this by increasing the money supply, by lowering interest rates for example, in an effort to combat a recession. The increased money supply props up the demand for goods and services, though demand would normally drop during a recession.


title: Stagflation

text: In the Keynesian model, higher prices prompt increases in the supply of goods and services. However, during a supply shock (i.e., scarcity, "bottleneck" in resources, etc.), supplies do not respond as they normally would to these price pressures. So, inflation jumps and output drops, producing stagflation.


title: Stagflation

text: Following Richard Nixon's imposition of wage and price controls on 15 August 1971, an initial wave of cost-push shocks in commodities were blamed for causing spiraling prices. The second major shock was the 1973 oil crisis, when the Organization of Petroleum Exporting Countries (OPEC) constrained the worldwide supply of oil. Both events, combined with the overall energy shortage that characterised the 1970s, resulted in actual or relative scarcity of raw materials. The price controls resulted in shortages at the point of purchase, causing, for example, queues of consumers at fuelling stations and increased production costs for industry.


title: Stagflation

text: Through the mid-1970s, it was alleged that none of the major macroeconomic models (Keynesian, New Classical, and monetarist) were able to explain stagflation.


title: Stagflation

text: Later, an explanation was provided based on the effects of adverse supply shocks on both inflation and output. According to Blanchard (2009), these adverse events were one of two components of stagflation; the other was "ideas"—which Robert Lucas, Thomas Sargent, and Robert Barro were cited as expressing as "wildly incorrect" and "fundamentally flawed" predictions (of Keynesian economics) which, they said, left stagflation to be explained by "contemporary students of the business cycle". In this discussion, Blanchard hypothesizes that the recent oil price increases could trigger another period of stagflation, although this has not yet happened (pg. 152).


title: Stagflation

text: A purely neoclassical view of the macroeconomy rejects the idea that monetary policy can have real effects. Neoclassical macroeconomists argue that real economic quantities, like real output, employment, and unemployment, are determined by real factors only. Nominal factors like changes in the money supply only affect nominal variables like inflation. The neoclassical idea that nominal factors cannot have real effects is often called "monetary neutrality" or also the "classical dichotomy".


title: Stagflation

text: Since the neoclassical viewpoint says that real phenomena like unemployment are essentially unrelated to nominal phenomena like inflation, a neoclassical economist would offer two separate explanations for 'stagnation' and 'inflation'. Neoclassical explanations of stagnation (low growth and high unemployment) include inefficient government regulations or high benefits for the unemployed that give people less incentive to look for jobs. Another neoclassical explanation of stagnation is given by real business cycle theory, in which any decrease in labour productivity makes it efficient to work less. The main neoclassical explanation of inflation is very simple: it happens when the monetary authorities increase the money supply too much.


title: Stagflation

text: In the neoclassical viewpoint, the real factors that determine output and unemployment affect the aggregate supply curve only. The nominal factors that determine inflation affect the aggregate demand curve only. When some adverse changes in real factors are shifting the aggregate supply curve left at the same time that unwise monetary policies are shifting the aggregate demand curve right, the result is stagflation.


title: Stagflation

text: Thus the main explanation for stagflation under a classical view of the economy is simply policy errors that affect both inflation and the labour market. Ironically, a very clear argument in favour of the classical explanation of stagflation was provided by Keynes himself. In 1919, John Maynard Keynes described the inflation and economic stagnation gripping Europe in his book "The Economic Consequences of the Peace". Keynes wrote:


title: Stagflation

text: Lenin is said to have declared that the best way to destroy the Capitalist System was to debauch the currency. By a continuing process of inflation, governments can confiscate, secretly and unobserved, an important part of the wealth of their citizens. By this method they not only confiscate, but they confiscate arbitrarily; and, while the process impoverishes many, it actually enriches some. [...] Lenin was certainly right. There is no subtler, no surer means of overturning the existing basis of society than to debauch the currency. The process engages all the hidden forces of economic law on the side of destruction, and does it in a manner which not one man in a million is able to diagnose.


title: Stagflation

text: The inflationism of the currency systems of Europe has proceeded to extraordinary lengths. The various belligerent Governments, unable, or too timid or too short-sighted to secure from loans or taxes the resources they required, have printed notes for the balance.


title: Stagflation

text: The presumption of a spurious value for the currency, by the force of law expressed in the regulation of prices, contains in itself, however, the seeds of final economic decay, and soon dries up the sources of ultimate supply. If a man is compelled to exchange the fruits of his labours for paper which, as experience soon teaches him, he cannot use to purchase what he requires at a price comparable to that which he has received for his own products, he will keep his produce for himself, dispose of it to his friends and neighbours as a favour, or relax his efforts in producing it. A system of compelling the exchange of commodities at what is not their real relative value not only relaxes production, but leads finally to the waste and inefficiency of barter.


title: Stagflation

text: In Germany the total expenditure of the Empire, the Federal States, and the Communes in 1919–20 is estimated at 25 milliards of marks, of which not above 10 milliards are covered by previously existing taxation. This is without allowing anything for the payment of the indemnity. In Russia, Poland, Hungary, or Austria such a thing as a budget cannot be seriously considered to exist at all. Thus the menace of inflationism described above is not merely a product of the war, of which peace begins the cure. It is a continuing phenomenon of which the end is not yet in sight.


title: Stagflation

text: While most economists believe that changes in money supply can have some real effects in the short run, neoclassical and neo-Keynesian economists tend to agree that there are no long-run effects from changing the money supply. Therefore, even economists who consider themselves neo-Keynesians usually believe that in the long run, money is neutral. In other words, while neoclassical and neo-Keynesian models are often seen as competing points of view, they can also be seen as two descriptions appropriate for different time horizons. Many mainstream textbooks today treat the neo-Keynesian model as a more appropriate description of the economy in the short run, when prices are 'sticky', and treat the neoclassical model as a more appropriate description of the economy in the long run, when prices have sufficient time to adjust fully.


title: Stagflation

text: Therefore, while mainstream economists today might often attribute short periods of stagflation (not more than a few years) to adverse changes in supply, they would not accept this as an explanation of very prolonged stagflation. More prolonged stagflation would be explained as the effect of inappropriate government policies: excessive regulation of product markets and labour markets leading to long-run stagnation, and excessive growth of the money supply leading to long-run inflation.


title: Stagflation

text: Political economists Jonathan Nitzan and Shimshon Bichler have proposed an explanation of stagflation as part of a theory they call differential accumulation, which says firms seek to beat the average profit and capitalisation rather than maximise. According to this theory, periods of mergers and acquisitions oscillate with periods of stagflation. When mergers and acquisitions are no longer politically feasible (governments clamp down with anti-monopoly rules), stagflation is used as an alternative to have higher relative profit than the competition. With increasing mergers and acquisitions, the power to implement stagflation increases.


title: Stagflation

text: Stagflation appears as a societal crisis, such as during the period of the oil crisis in the 70s and in 2007 to 2010. Inflation in stagflation, however, does not affect all firms equally. Dominant firms are able to increase their own prices at a faster rate than competitors. While in the aggregate no one appears to profit, differentially dominant firms improve their positions with higher relative profits and higher relative capitalisation. Stagflation is not due to any actual supply shock, but because of the societal crisis that hints at a supply crisis. It is mostly a 20th and 21st century phenomenon that has been mainly used by the "weapondollar-petrodollar coalition" creating or using Middle East crises for the benefit of pecuniary interests.


title: Stagflation

text: Demand-pull stagflation theory explores the idea that stagflation can result exclusively from monetary shocks without any concurrent supply shocks or negative shifts in economic output potential. Demand-pull theory describes a scenario where stagflation can occur following a period of monetary policy implementations that cause inflation. This theory was first proposed in 1999 by Eduardo Loyo of Harvard University's John F. Kennedy School of Government.


title: Stagflation

text: Supply-side economics emerged as a response to US stagflation in the 1970s. It largely attributed inflation to the ending of the Bretton Woods system in 1971 and the lack of a specific price reference in the subsequent monetary policies (Keynesian and Monetarism). Supply-side economists asserted that the contraction component of stagflation resulted from an inflation-induced rise in real tax rates (see bracket creep).


title: Stagflation

text: Adherents to the Austrian School maintain that creation of new money ex nihilo benefits the creators and early recipients of the new money relative to late recipients. Money creation is not wealth creation; it merely allows early money recipients to outbid late recipients for resources, goods, and services. Since the actual producers of wealth are typically late recipients, increases in the money supply weakens wealth formation and undermines the rate of economic growth. Austrian economist Frank Shostak says: "The increase in the money supply rate of growth coupled with the slowdown in the rate of growth of goods produced is what the increase in the rate of price inflation is all about. (Note that a price is the amount of money paid for a unit of a good.) What we have here is a faster increase in price inflation and a decline in the rate of growth in the production of goods. But this is exactly what stagflation is all about, i.e., an increase in price inflation and a fall in real economic growth. Popular opinion is that stagflation is totally made up. It seems therefore that the phenomenon of stagflation is the normal outcome of loose monetary policy. This is in agreement with [Phelps and Friedman (PF)]. Contrary to PF, however, we maintain that stagflation is not caused by the fact that in the short run people are fooled by the central bank. Stagflation is the natural result of monetary pumping which weakens the pace of economic growth and at the same time raises the rate of increase of the prices of goods and services."


title: Stagflation

text: In 1984, journalist and activist Jane Jacobs proposed the failure of major macroeconomic theories to explain stagflation was due to their focus on the nation as the salient unit of economic analysis, rather than the city. She proposed that the key to avoiding stagflation was for a nation to focus on the development of "import-replacing cities" that would experience economic ups and downs at different times, providing overall national stability and avoiding widespread stagflation. According to Jacobs, import-replacing cities are those with developed economies that balance their own production with domestic imports—so they can respond with flexibility as economic supply and demand cycles change. While lauding her originality, clarity, and consistency, urban planning scholars have criticised Jacobs for not comparing her own ideas to those of major theorists (e.g., Adam Smith, Karl Marx) with the same depth and breadth they developed, as well as a lack of scholarly documentation. Despite these issues, Jacobs' work is notable for having widespread public readership and influence on decision-makers.


title: Stagflation

text: Federal Reserve chairman Paul Volcker very sharply increased interest rates from 1979 to 1983 in what was called a "disinflationary scenario". After U.S. prime interest rates had soared into the double-digits, inflation did come down; these interest rates were the highest long-term prime interest rates that had ever existed in modern capital markets. Volcker is often credited with having stopped at least the inflationary side of stagflation, although the American economy also dipped into recession. Starting in approximately 1983, growth began a recovery. Both fiscal stimulus and money supply growth were policy at this time. A five- to six-year jump in unemployment during the Volcker disinflation suggests Volcker may have trusted unemployment to self-correct and return to its natural rate within a reasonable period.


title: Yoda

text: Yoda () is a fictional character in the "Star Wars" universe, first appearing in the 1980 film "The Empire Strikes Back". He is a small, green humanoid alien who is powerful with the Force and is a leading member of the Jedi Order until its near annihilation. In "The Empire Strikes Back", Yoda was voiced and puppeteered by Frank Oz, who reprised the role in "Return of the Jedi", the prequel trilogy, and the sequel trilogy. Outside of the films, the character has been mainly voiced by Tom Kane, starting with the 2003 "" animated television series. Yoda is an iconic figure in popular culture due to his distinct pattern of speech and role as a wise mentor.


title: Yoda

text: In his first appearance in the original trilogy, Yoda is described as the mentor of Obi-Wan Kenobi, and lives in exile on the swamp planet of Dagobah. He trains Luke Skywalker in the ways of the Force until his death at the age of 900 in "Return of the Jedi", though he later returns as a Force spirit. In the prequel trilogy, Yoda leads the Jedi High Council and trains the young generations of Jedi until they are assigned to a master. When the Clone Wars breaks out, he becomes a general in the Galactic Republic's army and leads several legions of clone troopers. Yoda is one of the few Jedi to survive the events of Order 66 at the end of the war, when he battles Emperor Palpatine and is forced to go into hiding. Yoda's spirit appears again in the sequel trilogy, advising an older Luke on his training of Rey.


title: Yoda

text: Franchise creator George Lucas has stated that he originally had Obi-Wan Kenobi training Luke Skywalker, but decided that it would not make sense to have him standing around watching Luke do all the fighting in the films and not help him, so he killed him off in the first film. He then created a new character, Yoda, to have someone train Luke. Lucas approached Jim Henson to voice the character; Henson was busy with other projects but recommended Frank Oz for the role.


title: Yoda

text: According to the make-up artist Stuart Freeborn, Yoda's face is based on his own and Albert Einstein's (particularly the eye wrinkles of the latter). For "The Phantom Menace", he was redesigned to look younger. He was created using computer-generated imagery (CGI) for two distant shots in the 1999 release but remained mostly a puppet, with Stuart Freeborn's original design reinterpreted by Nick Dudman.


title: Yoda

text: Frank Oz provided Yoda's voice in each film and performed as lead puppeteer in "" (1980), "Episode VI – Return of the Jedi" (1983), "Episode I – The Phantom Menace" (1999) and "Episode VIII – The Last Jedi" (2017). He also performed a vocal cameo as Yoda in "Episode IX – The Rise of Skywalker" (2019). For some walking scenes in "The Empire Strikes Back" and "The Phantom Menace", dwarf actors Deep Roy and Warwick Davis appeared in costume as Yoda (though neither was credited). While Oz served as the primary performer, over the years he had been assisted by a multitude of other puppeteers, including: Kathryn Mullen ("Ep. V"), Wendy Froud ("Ep. V"), David Barclay ("Ep. V–VI"), Mike Quinn ("Ep. VI"), David Greenaway ("Ep. I" & "VI"), Don Austen ("Ep. I"), Kathy Smee ("Ep. I"), Dave Chapman ("Ep. VIII"), Damian Farrell ("Ep. VIII"), and Colin Purves ("Ep. VIII"). For the radio dramatizations of "The Empire Strikes Back" and "Return of the Jedi", Yoda was voiced by John Lithgow while Tom Kane voiced him in the and several video games.


title: Yoda

text: Rendered with computer animation in "Episode II – Attack of the Clones" and "Episode III – Revenge of the Sith", Yoda appeared in ways not previously possible, including his participation in elaborate fight scenes. In "Revenge of the Sith", his face appears in several big close-ups, demanding highly detailed CGI work. His digital incarnation, overseen by Rob Coleman, was deliberately designed to be consistent with the limitations of the puppet version, including the occasional ear-jiggling.


title: Yoda

text: Yoda was recreated in CGI for the 2011 Blu-ray release of "The Phantom Menace". A clip of the new CG Yoda from "The Phantom Menace" was first seen in the featurette "The Chosen One", included in the 2005 DVD release of "Revenge of the Sith". The 2012 theatrical 3D release of "The Phantom Menace" matches the 2011 cut featuring the CG version of Yoda.


title: Yoda

text: To perform Yoda in "The Empire Strikes Back", Frank Oz inserted his right hand into the puppet's head, using said hand to control Yoda's mouth, while his left hand controlled Yoda's left hand. A second puppeteer, Kathryn Mullen, assisted Oz on the Dagobah set, operating Yoda's right hand. Wendy Midener, a puppet builder who had worked with Oz and Mullen on "The Muppet Show", and later "The Dark Crystal" and "Labyrinth", was originally supposed to control Yoda's eyes, but when something on the set caused an allergic reaction for Midener, she was demoted to controlling Yoda's ears, with then-newcomer David Barclay operating the eyes instead (Barclay also substituted for Oz as lead Yoda puppeteer for production shoots when Oz was unavailable). For wide shots of Yoda moving around, actor and stunt performer Deep Roy wore a life-sized Yoda costume.


title: Yoda

text: Grand Master Yoda is among the oldest, most stoic, and most powerful Jedi Masters in the "Star Wars" universe. George Lucas opted to have many details of the character's life history remain unknown. Yoda's race and home world have not been named in any official media, canonical or otherwise, and he is merely said to be of a "species unknown" by the "Star Wars" Databank. Yoda's characteristic speech patterns were conceived by Lucas and Lawrence Kasdan, and developed by Oz. Academic syntacticians have found them somewhat inconsistent, but have extrapolated that they possess object–subject–verb (OSV) word order, making them anastrophic.


title: Yoda

text: The films and Expanded Universe reveal that Yoda had a hand in training almost every Jedi Master in the galaxy. In the "Star Wars" prequel films, he instructs several younglings in the Jedi Temple before they are assigned to a master. In "The Empire Strikes Back" he mentions that he had been training Jedi "for 800 years", which means he must have been a Master Jedi for quite some time before that.


title: Yoda

text: Yoda makes his first film appearance in "The Empire Strikes Back". Luke Skywalker (Mark Hamill) arrives on Dagobah to seek his guidance, having been instructed to do so by the Force ghost of Obi-Wan Kenobi (Alec Guinness), who describes him as "the Jedi Master who instructed me."


title: Yoda

text: Yoda does not initially identify himself to Luke and instead tests his patience by presenting himself as a comical backwater individual, deliberately provoking both Luke and R2-D2. Luke is shocked when he finally discovers that this small, eccentric creature is the powerful Jedi Master he was seeking. Finding that Luke has the same anger and recklessness which caused his father's downfall, Yoda is reluctant to teach him the ways of the Force and agrees only at Obi-Wan's behest. Before finishing his training, Luke chooses to leave Dagobah in order to confront Darth Vader and save his friends on Bespin. Yoda and Obi-Wan warn him that he is not ready to face Vader and is being lured into a trap but Luke leaves anyway. When Obi-Wan laments that Luke is their "last hope," Yoda reminds him that "there is another."


title: Yoda

text: Yoda makes a brief appearance in "Return of the Jedi", set a year after "The Empire Strikes Back". Now sick and frail, Yoda informs Luke that he has completed his training but will not be a Jedi until he confronts Darth Vader; he also confirms that Vader is Luke's father, something Vader had told Luke in the previous film. Yoda then peacefully dies at the age of 900, his body disappearing as he becomes "one with the Force". He leaves Luke with the knowledge that "there is another Skywalker." Moments later, Obi-Wan's ghost helps Luke come to the realization that the "other" of whom Yoda spoke is his twin sister, Princess Leia.


title: Yoda

text: In the film's final scene, after the Empire has been defeated, Luke sees Yoda's spirit looking upon him with pride alongside Obi-Wan and the redeemed Anakin Skywalker, Vader's former Jedi self.


title: Yoda

text: Yoda returns as a younger version of himself in the prequel trilogy beginning with "The Phantom Menace". The film marked the final time Oz would portray the character as a puppet until the release of "The Last Jedi" (2017). However, in the 2011 Blu-ray release of "The Phantom Menace", the Yoda puppet was replaced by a CGI character to match the later depiction of the character. In the film, which is set 35 years before "The Empire Strikes Back", Jedi Master Qui-Gon Jinn brings the young Anakin Skywalker to the Jedi Council. Qui-Gon is convinced that Anakin is the "Chosen One" of Jedi prophecy who will bring balance to the Force and requests the boy be trained as a Jedi. Yoda senses great fear in Anakin, especially in regards to his attachment to his mother Shmi, and foresees "grave danger" in his training. The council, led at the time by Yoda's former padawan Mace Windu, rejects Qui-Gon's request.


title: Yoda

text: When Qui-Gon is mortally wounded in a duel with Sith Lord Darth Maul, his dying request to his Padawan Obi-Wan Kenobi (Ewan McGregor) is that Anakin be trained as a Jedi. Obi-Wan, determined to fulfill his promise to his master, tells Yoda that he will train the boy, even without the council's approval. Yoda makes Obi-Wan a Jedi knight and reluctantly gives his blessing to Anakin's training.


title: Yoda

text: Yoda makes his first CGI appearance in "Attack of the Clones", set a decade after "The Phantom Menace". Yoda, now in direct control of the Order's policy as Master of the High Council in addition to his traditional position as Grandmaster, is one of the many Jedi who are concerned about the emergence of the Confederacy of Independent Systems, a secessionist movement wanting independence from the Galactic Republic. After the first attempted assassination of Senator Padmé Amidala, Chancellor Palpatine suggests that she be put under the protection of Obi-Wan, who is training Anakin. In a deleted scene, a meditating Yoda senses Anakin slaughtering the Tusken Raiders who murdered his mother.


title: Yoda

text: At the climax of the film, Yoda arrives in time to save Obi-Wan and Anakin from the Separatists and defeats his former apprentice, Count Dooku, the Separatists’ leader and a Sith lord, in a lightsaber duel.


title: Yoda

text: In "Revenge of the Sith", Yoda leads the Jedi Council in pursuing the mysterious Sith Lord Darth Sidious. Palpatine has by then amassed near-dictatorial emergency powers and begins interfering in Jedi affairs by appointing Anakin as his personal representative on the council. The Council grants Anakin a Council seat but denies him the rank of Master, feeling that doing so would amount to giving Palpatine a vote in the council. Additionally they order him to spy on Palpatine, whom Anakin considers a friend and mentor.


title: Yoda

text: Anakin seeks Yoda's counsel about his prophetic visions that someone close to him will die. Yoda, unaware that the person of whom Anakin speaks is Padmé, or that she is Anakin's wife and pregnant with his child, tells him to "train yourself to let go of everything that you fear to lose." Unsatisfied, Anakin turns to Palpatine, who then reveals himself as Darth Sidious. Sidious manipulates the young Jedi into becoming his Sith apprentice, Darth Vader, with the promise that the dark side of the Force holds the power to save Padmé from dying in childbirth.


title: Yoda

text: Sidious later transforms the Republic into the tyrannical Galactic Empire, proclaiming himself emperor for life and ordering the clone troopers to kill their Jedi generals. Yoda is on Kashyyyk, overseeing the battle between the Separatist forces and a combined command of clone troopers and Wookiees. Through the Force, Yoda feels the deaths of each of the Jedi as they are assassinated by their own troops. After swiftly killing the clone troopers instructed to kill him, he escapes with Wookiee leaders Tarfful and Chewbacca to Coruscant, where he and Obi-Wan fight their way into the Jedi Temple to stop a trap for all surviving Jedi. Inside, they discover that all the Jedi inside, younglings included, have been slaughtered. They then discover a holographic recording revealing Vader as the assassin. Yoda decides to face Sidious, sending Obi-Wan to kill Vader. When Obi-Wan protests, Yoda tells him that the Anakin he knew no longer exists, having been "consumed by Darth Vader."


title: Yoda

text: Subsequently, Yoda battles Sidious in a lightsaber duel that damages the Senate Rotunda. In the end, neither is able to overcome the other and Yoda is forced to retreat. He goes into exile on Dagobah so that he may hide from the Empire and wait for another opportunity to destroy the Sith. At the end of the film, it is revealed that Yoda has been in contact with Qui-Gon's spirit, learning the secret of immortality from him and passing it on to Obi-Wan.


title: Yoda

text: Yoda is also instrumental in deciding the fate of the Skywalker children after Padmé dies in childbirth, recommending that Luke and Leia be hidden from Vader and Sidious; he sends Leia to be adopted by Senator Bail Organa of Alderaan, and Luke to Vader's stepfamily Owen and Beru Lars on Tatooine. Other than the ancient Jedi Master, only the Organas, the Lars family, R2-D2 and Obi-Wan know of their true identities.


title: Yoda

text: In "", set 30 years after Yoda's death in "Return of the Jedi", Yoda's voice is heard by the young scavenger Rey in a Force vision after she discovers Luke Skywalker's lightsaber under a castle owned by Maz Kanata.


title: Yoda

text: In "The Last Jedi", Yoda appears to Luke as a Force spirit as he debates whether to burn down the tree storing the Sacred Texts of the Jedi. As Luke makes his way to the tree, Yoda appears behind him and reminds him that a Jedi must always be sure of his path. When Luke decides to burn down the tree, Yoda summons a lightning bolt and sets it ablaze. When confronting Yoda as to why he did it, Yoda assures Luke that the books contained no knowledge that Rey didn't already possess. He stressed that true Jedi knowledge was not found in books but within Jedi themselves—and it is their responsibility to pass that knowledge on, reminding him, "The greatest teacher, failure is." As Luke takes in the message, he shares a quiet moment with his former master, who informs him that the burden of all masters is being surpassed by their students.


title: Yoda

text: Unlike in the prequels, where fight scenes necessitated the character be rendered in with computer-generated imagery, Yoda is once more portrayed using puppetry, with Frank Oz once again both puppeteering (with three assistants) and voicing the character.


title: Yoda

text: Yoda is heard in "Star Wars: The Rise of Skywalker" as one of the voices of Jedi past who speak to Rey during her battle against the reborn Darth Sidious.


title: Yoda

text: Yoda appears in the 2003 Cartoon Network 2D-animated television series "Star Wars: Clone Wars", voiced by Tom Kane. In the show, Yoda is made a general, like many of the Jedi Knights and Masters. Yoda escorts Padmé on their journey to an unspecified planet, but Yoda senses several Jedi in distress on Ilum. Using the Jedi mind trick to convince Captain Typho to take them to Ilum, Yoda saves two Jedi Knights and finds a message from Count Dooku giving orders to destroy the Jedi Temple on Ilum. In the animated series' final episode, Yoda fights side by side with Mace Windu to defend Coruscant, which is under attack from the Separatists. The two Jedi Masters realize too late that the battle is a distraction; Separatist leader General Grievous truly intends to kidnap Palpatine. The Jedi Master's effort to stop Grievous fails, and Palpatine is taken hostage, thus setting the stage for "Revenge of the Sith".


title: Yoda

text: Yoda appears in "The Clone Wars", again voiced by Tom Kane. In , Yoda assigns Anakin Skywalker his own padawan, Ahsoka Tano as he believes that she will help Anakin grow as a Jedi and as a person. Throughout most of the series, Yoda spends his time on Coruscant with the Jedi Council but he occasionally leaves for certain tasks, such as negotiations with King Katuunko on Rugosa and a confrontation with Asajj Ventress's droid army. Yoda also watches over Anakin and Ahsoka throughout the series, pleased that they are both maturing with each other's influence. However, in the final arc of season five, Ahsoka is framed for a crime she didn't commit and Yoda and the Jedi Council turn her over to the Republic military. Along with other members of the council, Yoda observes Ahsoka's trial but Anakin bursts in with the true culprit, fallen Jedi Barriss Offee, before the verdict can be read. Afterwards Yoda, Anakin, and the Council personally invite Ahsoka to rejoin the Order but she refuses and leaves. According to show runner Dave Filoni, Yoda blames himself for Ahsoka's departure as he had made her Anakin's padawan in the first place.


title: Yoda

text: In the final arc of the sixth season, Yoda hears Qui-Gon Jinn speaking to him from beyond the grave. Yoda flees the Jedi Temple with R2-D2 to travel to Dagobah, his future home, to find answers. Shown cryptic visions of the fall of the Jedi, Yoda learns he has been chosen to manifest his consciousness after death as a Force ghost. Yoda is tested by a group of spirit priestesses in order to overcome trials and temptations on his pilgrimage; one of these tests is to face an illusion of ancient Sith lord Darth Bane. Yoda's final test is to resist an attempt by Darth Sidious and Dooku to lure him to the dark side with a false vision of deceased Jedi Master Sifo Dyas. Yoda engages in a metaphysical battle with Sidious and appears to sacrifice his life in order to save Anakin's–only to awaken and discover that the battle was merely a vision and that he has passed the test. The priestesses inform Yoda that his training will resume in time.


title: Yoda

text: Yoda was heard in the "Star Wars Rebels" episode "Path of the Jedi" with Frank Oz reprising the role for the first time since "Revenge of the Sith". He communicates with padawan Ezra Bridger and his master Kanan Jarrus during their experience in an ancient temple on Lothal, helping the pair do some soul-searching to analyze their true motivations. He appears physically for the first time in the season two episode "Shroud of Darkness", in which he appears in a vision of Ezra's and reunites with Ahsoka. His appearance in the series differs from his usual countenance as an homage to an early Ralph McQuarrie design for the character as well as a classic Kenner action figure. This was justified by premise that Ezra is viewing the character through his own imagination, but the decision was confusing to many viewers.


title: Yoda

text: Yoda is seen in two of the six episodes of Tales of the Jedi, in a non-speaking role. His first appearance can be found in the third episode of the anthology miniseries, titled "Choices", in which he attends the funeral of Jedi Master Katri. The Jedi Grand Master's second appearance in the series can be found within its fifth episode, "Practice Makes Perfect". In this, Yoda is present alongside other Jedi Masters, including Mace Windu, watching Padawan Ahsoka Tano being tested against training remotes designed to simulate battle droids. In his final appearance in the series (within the same episode), Yoda, alongside Obi-Wan Kenobi, lays witness to a conversation between Anakin Skywalker and Ahsoka Tano, in which Skywalker informs Tano that he will formulate a test more challenging than the one she just partook in.


title: Yoda

text: Yoda appears extensively in the "Star Wars Expanded Universe", mostly in works set during or before the prequel trilogy, including Sean Stewart's 2004 novel "Yoda: Dark Rendezvous", in which he sends an impersonator of himself to negotiate a potential treaty with Dooku, suspected his offer to be a feint. He also appears as a supporting character in Dark Horse Comics' "", and various other Clone Wars-related titles. In April 2014, following The Walt Disney Company's acquisition of Lucasfilm, all of these works were rebranded as "Star Wars Legends" and declared non-canon to the rest of the franchise.


title: Yoda

text: Since 2014, Yoda has also been featured in a number of canon books and other works, including "Dooku: Jedi Lost" and "Master & Apprentice", which take place before "The Phantom Menace". He is set to appear in the upcoming "", set 200 years before the prequel trilogy.


title: Yoda

text: In 1980, American musician and parody artist "Weird Al" Yankovic wrote and recorded a parody of the Kinks' "Lola", called "Yoda". It was later rerecorded for his 1985 album "Dare to Be Stupid", after Yankovic was able to obtain permission from both George Lucas and the Kinks.


title: Yoda

text: In 2007, Yoda was selected by "Empire" magazine as the "25th greatest movie character of all time." On their list of the "100 Greatest Fictional Characters", Fandomania.com ranked Yoda at number 60.


title: Yoda

text: Linguistics professor David Ager from Queen Mary University of London says Yoda's language most closely resembles the Hawaiian language.


title: Yoda

text: In 2017, a photoshopped image of Yoda seated next to King Faisal at the signing of the Charter of the United Nations in San Francisco in 1945 was inadvertently printed in a social studies textbook. The textbook was withdrawn once the error was discovered.


title: Yoda

text: In 2019, discount store Poundland used the voice of Yoda at its self-service checkouts in stores across the United Kingdom.


title: Western Front (World War I)

text: The Western Front was one of the main theatres of war during the First World War. Following the outbreak of war in August 1914, the German Army opened the Western Front by invading Luxembourg and Belgium, then gaining military control of important industrial regions in France. The German advance was halted with the Battle of the Marne. Following the Race to the Sea, both sides dug in along a meandering line of fortified trenches, stretching from the North Sea to the Swiss frontier with France, which changed little except during early 1917 and in 1918.


title: Western Front (World War I)

text: Between 1915 and 1917 there were several offensives along this front. The attacks employed massive artillery bombardments and massed infantry advances. Entrenchments, machine gun emplacements, barbed wire and artillery repeatedly inflicted severe casualties during attacks and counter-attacks and no significant advances were made. Among the most costly of these offensives were the Battle of Verdun, in 1916, with a combined 700,000 casualties, the Battle of the Somme, also in 1916, with more than a million casualties, and the Battle of Passchendaele, in 1917, with 487,000 casualties.


title: Western Front (World War I)

text: To break the deadlock of trench warfare on the Western Front, both sides tried new military technology, including poison gas, aircraft, and tanks. The adoption of better tactics and the cumulative weakening of the armies in the west led to the return of mobility in 1918. The German spring offensive of 1918 was made possible by the Treaty of Brest-Litovsk that ended the war of the Central Powers against Russia and Romania on the Eastern Front. Using short, intense "hurricane" bombardments and infiltration tactics, the German armies moved nearly to the west, the deepest advance by either side since 1914, but the result was indecisive.


title: Western Front (World War I)

text: The unstoppable advance of the Allied armies during the Hundred Days Offensive of 1918 caused a sudden collapse of the German armies and persuaded the German commanders that defeat was inevitable. The German government surrendered in the Armistice of 11 November 1918, and the terms of peace were settled by the Treaty of Versailles in 1919.


title: Western Front (World War I)

text: The Western Front was the place where the most powerful military forces in Europe, the German and French armies, met and where the First World War was decided. At the outbreak of the war, the German Army, with seven field armies in the west and one in the east, executed a modified version of the Schlieffen Plan, bypassing French defenses along the common border by moving quickly through neutral Belgium, and then turning southwards to attack France and attempt to encircle the French Army and trap it on the German border. Belgian neutrality had been guaranteed by Britain under the Treaty of London, 1839; this caused Britain to join the war at the expiration of its ultimatum at midnight on 4 August. Armies under German generals Alexander von Kluck and Karl von Bülow attacked Belgium on 4 August 1914. Luxembourg had been occupied without opposition on 2 August. The first battle in Belgium was the Siege of Liège, which lasted from 5–16 August. Liège was well fortified and surprised the German Army under Bülow with its level of resistance. German heavy artillery was able to demolish the main forts within a few days. Following the fall of Liège, most of the Belgian field army retreated to Antwerp, leaving the garrison of Namur isolated, with the Belgian capital, Brussels, falling to the Germans on 20 August. Although the German army bypassed Antwerp, it remained a threat to their flank. Another siege followed at Namur, lasting from about 20–23 August.


title: Western Front (World War I)

text: The French deployed five armies on the frontier. The French Plan XVII was intended to bring about the capture of Alsace-Lorraine. On 7 August, the VII Corps attacked Alsace to capture Mulhouse and Colmar. The main offensive was launched on 14 August with the First and Second Armies attacking toward Sarrebourg-Morhange in Lorraine. In keeping with the Schlieffen Plan, the Germans withdrew slowly while inflicting severe losses upon the French. The French Third and Fourth Armies advanced toward the Saar River and attempted to capture Saarburg, attacking Briey and Neufchateau but were repulsed. The French VII Corps captured Mulhouse after a brief engagement first on 7 August, and then again on 23 August, but German reserve forces engaged them in the Battle of Mulhouse and forced the French to retreat twice.


title: Western Front (World War I)

text: The German Army swept through Belgium, executing civilians and razing villages. The application of "collective responsibility" against a civilian population further galvanised the allies. Newspapers condemned the German invasion, violence against civilians and destruction of property, which became known as the "Rape of Belgium." After marching through Belgium, Luxembourg and the Ardennes, the Germans advanced into northern France in late August, where they met the French Army, under Joseph Joffre, and the divisions of the British Expeditionary Force under Field Marshal Sir John French. A series of engagements known as the Battle of the Frontiers ensued, which included the Battle of Charleroi and the Battle of Mons. In the former battle the French Fifth Army was almost destroyed by the German 2nd and 3rd Armies and the latter delayed the German advance by a day. A general Allied retreat followed, resulting in more clashes at the Battle of Le Cateau, the Siege of Maubeuge and the Battle of St. Quentin (also called the First Battle of Guise).


title: Western Front (World War I)

text: The German Army came within of Paris but at the First Battle of the Marne (6–12 September), French and British troops were able to force a German retreat by exploiting a gap which appeared between the 1st and 2nd Armies, ending the German advance into France. The German Army retreated north of the Aisne River and dug in there, establishing the beginnings of a static western front that was to last for the next three years. Following this German retirement, the opposing forces made reciprocal outflanking manoeuvres, known as the Race for the Sea and quickly extended their trench systems from the Swiss frontier to the North Sea. The territory occupied by Germany held 64 percent of French pig-iron production, 24 percent of its steel manufacturing and 40 percent of the coal industry – dealing a serious blow to French industry.


title: Western Front (World War I)

text: On the Entente side (those countries opposing the German alliance), the final lines were occupied with the armies of each nation defending a part of the front. From the coast in the north, the primary forces were from Belgium, the British Empire and then France. Following the Battle of the Yser in October, the Belgian army controlled a length of West Flanders along the coast, known as the Yser Front, along the Yser river and the Yperlee canal, from Nieuwpoort to Boesinghe. Meanwhile, the British Expeditionary Force (BEF) occupied a position on the flank, having occupied a more central position.


title: Western Front (World War I)

text: From 19 October until 22 November, the German forces made their final breakthrough attempt of 1914 during the First Battle of Ypres, which ended in a mutually-costly stalemate. After the battle, Erich von Falkenhayn judged that it was no longer possible for Germany to win the war by purely military means and on 18 November 1914 he called for a diplomatic solution. The Chancellor, Theobald von Bethmann-Hollweg; "Generalfeldmarschall" Paul von Hindenburg, commanding "Ober Ost" (Eastern Front high command); and his deputy, Erich Ludendorff, continued to believe that victory was achievable through decisive battles. During the Lodz offensive in Poland Falkenhayn hoped that the Russians would be made amenable to peace overtures. In his discussions with Bethmann-Hollweg, Falkenhayn viewed Germany and Russia as having no insoluble conflict and that the real enemies of Germany were France and Britain. A peace with only a few annexations of territory also seemed possible with France and that with Russia and France out of the war by negotiated settlements, Germany could concentrate on Britain and fight a long war with the resources of Europe at its disposal. Hindenburg and Ludendorff continued to believe that Russia could be defeated by a series of battles which cumulatively would have a decisive effect, after which Germany could finish off France and Britain.


title: Western Front (World War I)

text: Trench warfare in 1914, while not new, quickly improved and provided a very high degree of defense. According to two prominent historians:


title: Western Front (World War I)

text: Between the coast and the Vosges was a westward bulge in the trench line, named the Noyon salient for the captured French town at the maximum point of advance near Compiègne. Joffre's plan for 1915 was to attack the salient on both flanks to cut it off. The Fourth Army had attacked in Champagne from 20 December 1914 – 17 March 1915 but the French were not able to attack in Artois at the same time. The Tenth Army formed the northern attack force and was to attack eastwards into the Douai plain across a front between Loos and Arras. On 10 March, as part of the larger offensive in the Artois region, the British Army fought the Battle of Neuve Chapelle to capture Aubers Ridge. The assault was made by four divisions along a front. Preceded by a surprise bombardment lasting only 35 minutes, the initial assault made rapid progress and the village was captured within four hours. The advance then slowed because of supply and communication difficulties. The Germans brought up reserves and counter-attacked, forestalling the attempt to capture the ridge. Since the British had used about one-third of their supply of artillery ammunition, General Sir John French blamed the failure on the shortage of ammunition, despite the early success.


title: Western Front (World War I)

text: All sides had signed the Hague Conventions of 1899 and 1907, which prohibited the use of chemical weapons in warfare. In 1914, there had been small-scale attempts by both the French and Germans to use various tear gases, which were not strictly prohibited by the early treaties but which were also ineffective. The first use of more lethal chemical weapons on the Western Front was against the French near the Belgian town of Ypres. The Germans had already deployed gas against the Russians in the east at the Battle of Bolimów.


title: Western Front (World War I)

text: Despite the German plans to maintain the stalemate with the French and British, Albrecht, Duke of Württemberg, commander of the 4th Army planned an offensive at Ypres, site of the First Battle of Ypres in November 1914. The Second Battle of Ypres, April 1915, was intended to divert attention from offensives in the Eastern Front and disrupt Franco-British planning. After a two-day bombardment, the Germans released of of chlorine gas onto the battlefield. Though primarily a powerful irritant, it can asphyxiate in high concentrations or prolonged exposure. Being heavier than air, the gas crept across no man's land and drifted into the French trenches. The green-yellow cloud started killing some defenders and those in the rear fled in panic, creating an undefended gap in the Allied line. The Germans were unprepared for the level of their success and lacked sufficient reserves to exploit the opening. Canadian troops on the right drew back their left flank and halted the German advance. The gas attack was repeated two days later and caused a withdrawal of the Franco-British line but the opportunity had been lost.


title: Western Front (World War I)

text: The success of this attack would not be repeated, as the Allies countered by introducing gas masks and other countermeasures. An example of the success of these measures came a year later, on 27 April in the Gas attacks at Hulluch to the south of Ypres, where the 16th (Irish) Division withstood several German gas attacks. The British retaliated, developing their own chlorine gas and using it at the Battle of Loos in September 1915. Fickle winds and inexperience led to more British casualties from the gas than German. French, British and German forces all escalated the use of gas attacks through the rest of the war, developing the more deadly phosgene gas in 1915, then the infamous mustard gas in 1917, which could linger for days and could kill slowly and painfully. Countermeasures also improved and the stalemate continued.


title: Western Front (World War I)

text: Specialised aeroplanes for aerial combat were introduced in 1915. Aircraft were already in use for scouting and on 1 April, the French pilot Roland Garros became the first to shoot down an enemy aircraft by using a machine-gun that shot forward through the propeller blades. This was achieved by crudely reinforcing the blades to deflect bullets. Several weeks later Garros force-landed behind German lines. His aeroplane was captured and sent to Dutch engineer Anthony Fokker, who soon produced a significant improvement, the interrupter gear, in which the machine gun is synchronised with the propeller so it fires in the intervals when the blades of the propeller are out of the line of fire. This advance was quickly ushered into service, in the Fokker E.I ("Eindecker", or monoplane, Mark 1), the first single seat fighter aircraft to combine a reasonable maximum speed with an effective armament. Max Immelmann scored the first confirmed kill in an "Eindecker" on 1 August. Both sides developed improved weapons, engines, airframes and materials, until the end of the war. It also inaugurated the cult of the ace, the most famous being Manfred von Richthofen (the Red Baron). Contrary to the myth, anti-aircraft fire claimed more kills than fighters.


title: Western Front (World War I)

text: The final Entente offensive of the spring was the Second Battle of Artois, an offensive to capture Vimy Ridge and advance into the Douai plain. The French Tenth Army attacked on 9 May after a six-day bombardment and advanced to capture Vimy Ridge. German reinforcements counter-attacked and pushed the French back towards their starting points because French reserves had been held back and the success of the attack had come as a surprise. By 15 May the advance had been stopped, although the fighting continued until 18 June. In May the German Army captured a French document at La Ville-aux-Bois describing a new system of defence. Rather than relying on a heavily fortified front line, the defence was to be arranged in a series of echelons. The front line would be a thinly manned series of outposts, reinforced by a series of strongpoints and a sheltered reserve. If a slope was available, troops were deployed along the rear side for protection. The defence became fully integrated with command of artillery at the divisional level. Members of the German high command viewed this new scheme with some favour and it later became the basis of an elastic defence in depth doctrine against Entente attacks.


title: Western Front (World War I)

text: During the autumn of 1915, the "Fokker Scourge" began to have an effect on the battlefront as Allied reconnaissance aircraft were nearly driven from the skies. These reconnaissance planes were used to direct gunnery and photograph enemy fortifications but now the Allies were nearly blinded by German fighters. However, the impact of German air superiority was diminished by their primarily defensive doctrine in which they tended to remain over their own lines, rather than fighting over Allied held territory.


title: Western Front (World War I)

text: In September 1915 the Entente allies launched another offensive, with the French Third Battle of Artois, Second Battle of Champagne and the British at Loos. The French had spent the summer preparing for this action, with the British assuming control of more of the front to release French troops for the attack. The bombardment, which had been carefully targeted by means of aerial photography, began on 22 September. The main French assault was launched on 25 September and, at first, made good progress in spite of surviving wire entanglements and machine gun posts. Rather than retreating, the Germans adopted a new defence-in-depth scheme that consisted of a series of defensive zones and positions with a depth of up to .


title: Western Front (World War I)

text: On 25 September, the British began the Battle of Loos, part of the Third Battle of Artois, which was meant to supplement the larger Champagne attack. The attack was preceded by a four-day artillery bombardment of 250,000 shells and a release of 5,100 cylinders of chlorine gas. The attack involved two corps in the main assault and two corps performing diversionary attacks at Ypres. The British suffered heavy losses, especially due to machine gun fire during the attack and made only limited gains before they ran out of shells. A renewal of the attack on 13 October fared little better. In December, French was replaced by General Douglas Haig as commander of the British forces.


title: Western Front (World War I)

text: Falkenhayn believed that a breakthrough might no longer be possible and instead focused on forcing a French defeat by inflicting massive casualties. His new goal was to "bleed France white." As such, he adopted two new strategies. The first was the use of unrestricted submarine warfare to cut off Allied supplies arriving from overseas. The second would be attacks against the French army intended to inflict maximum casualties; Falkenhayn planned to attack a position from which the French could not retreat, for reasons of strategy and national pride and thus trap the French. The town of Verdun was chosen for this because it was an important stronghold, surrounded by a ring of forts, that lay near the German lines and because it guarded the direct route to Paris.


title: Western Front (World War I)

text: Falkenhayn limited the size of the front to to concentrate artillery firepower and to prevent a breakthrough from a counter-offensive. He also kept tight control of the main reserve, feeding in just enough troops to keep the battle going. In preparation for their attack, the Germans had amassed a concentration of aircraft near the fortress. In the opening phase, they swept the air space of French aircraft, which allowed German artillery-observation aircraft and bombers to operate without interference. In May, the French countered by deploying "escadrilles de chasse" with superior Nieuport fighters and the air over Verdun turned into a battlefield as both sides fought for air superiority.


title: Western Front (World War I)

text: The Battle of Verdun began on 21 February 1916 after a nine-day delay due to snow and blizzards. After a massive eight-hour artillery bombardment, the Germans did not expect much resistance as they slowly advanced on Verdun and its forts. Sporadic French resistance was encountered. The Germans took Fort Douaumont and then reinforcements halted the German advance by 28 February.


title: Western Front (World War I)

text: The Germans turned their focus to Le Mort Homme on the west bank of the Meuse which blocked the route to French artillery emplacements, from which the French fired across the river. After some of the most intense fighting of the campaign, the hill was taken by the Germans in late May. After a change in French command at Verdun from the defensive-minded Philippe Pétain to the offensive-minded Robert Nivelle, the French attempted to re-capture Fort Douaumont on 22 May but were easily repulsed. The Germans captured Fort Vaux on 7 June and with the aid of diphosgene gas, came within of the last ridge before Verdun before being contained on 23 June.


title: Western Front (World War I)

text: Over the summer, the French slowly advanced. With the development of the rolling barrage, the French recaptured Fort Vaux in November and by December 1916 they had pushed the Germans back from Fort Douaumont, in the process rotating 42 divisions through the battle. The Battle of Verdun—also known as the 'Mincing Machine of Verdun' or 'Meuse Mill'—became a symbol of French determination and self-sacrifice.


title: Western Front (World War I)

text: In the spring, Allied commanders had been concerned about the ability of the French Army to withstand the enormous losses at Verdun. The original plans for an attack around the River Somme were modified to let the British make the main effort. This would serve to relieve pressure on the French, as well as the Russians who had also suffered great losses. On 1 July, after a week of heavy rain, British divisions in Picardy began the Battle of the Somme with the Battle of Albert, supported by five French divisions on their right flank. The attack had been preceded by seven days of heavy artillery bombardment. The experienced French forces were successful in advancing but the British artillery cover had neither blasted away barbed wire, nor destroyed German trenches as effectively as was planned. They suffered the greatest number of casualties (killed, wounded and missing) in a single day in the history of the British Army, about 57,000.


title: Western Front (World War I)

text: The Verdun lesson learnt, the Allies' tactical aim became the achievement of air superiority and until September, German aircraft were swept from the skies over the Somme. The success of the Allied air offensive caused a reorganisation of the German air arm and both sides began using large formations of aircraft rather than relying on individual combat. After regrouping, the battle continued throughout July and August, with some success for the British despite the reinforcement of the German lines. By August, General Haig had concluded that a breakthrough was unlikely and instead, switched tactics to a series of small unit actions. The effect was to straighten out the front line, which was thought necessary in preparation for a massive artillery bombardment with a major push.


title: Western Front (World War I)

text: The final phase of the battle of the Somme saw the first use of the tank on the battlefield. The Allies prepared an attack that would involve 13 British and Imperial divisions and four French corps. The attack made early progress, advancing in places but the tanks had little effect due to their lack of numbers and mechanical unreliability. The final phase of the battle took place in October and early November, again producing limited gains with heavy loss of life. All told, the Somme battle had made penetrations of only and failed to reach the original objectives. The British had suffered about 420,000 casualties and the French around 200,000. It is estimated that the Germans lost 465,000, although this figure is controversial.


title: Western Front (World War I)

text: The Somme led directly to major new developments in infantry organisation and tactics; despite the terrible losses of 1 July, some divisions had managed to achieve their objectives with minimal casualties. In examining the reasons behind losses and achievements, once the British war economy produced sufficient equipment and weapons, the army made the platoon the basic tactical unit, similar to the French and German armies. At the time of the Somme, British senior commanders insisted that the company (120 men) was the smallest unit of manoeuvre; less than a year later, the section of ten men would be so.


title: Western Front (World War I)

text: In August 1916 the German leadership along the Western Front had changed as Falkenhayn resigned and was replaced by Hindenburg and Ludendorff. The new leaders soon recognised that the battles of Verdun and the Somme had depleted the offensive capabilities of the German Army. They decided that the German Army in the west would go over to the strategic defensive for most of 1917, while the Central powers would attack elsewhere.


title: Western Front (World War I)

text: During the Somme battle and through the winter months, the Germans created a fortification behind the Noyon Salient that would be called the Hindenburg Line, using the defensive principles elaborated since the defensive battles of 1915, including the use of Eingreif divisions. This was intended to shorten the German front, freeing 10 divisions for other duties. This line of fortifications ran from Arras south to St Quentin and shortened the front by about . British long-range reconnaissance aircraft first spotted the construction of the Hindenburg Line in November 1916.


title: Western Front (World War I)

text: The Hindenburg Line was built between and behind the German front line. On 25 February the German armies west of the line began Operation Alberich a withdrawal to the line and completed the retirement on 5 April, leaving a supply desert of scorched earth to be occupied by the Allies. This withdrawal negated the French strategy of attacking both flanks of the Noyon salient, as it no longer existed. The British continued offensive operations as the War Office claimed, with some justice, that this withdrawal resulted from the casualties the Germans received during the Battles of the Somme and Verdun, despite the Allies suffering greater losses.


title: Western Front (World War I)

text: On 6 April the United States declared war on Germany. In early 1915, following the sinking of the , Germany had stopped unrestricted submarine warfare in the Atlantic because of concerns of drawing the United States into the conflict. With the growing discontent of the German public due to the food shortages, the government resumed unrestricted submarine warfare in February 1917. The calculated that a successful submarine and warship siege of Britain would force that country out of the war within six months, while American forces would take a year to become a serious factor on the Western Front. The submarine and surface ships had a long period of success before Britain resorted to the convoy system, bringing a large reduction in shipping losses.


title: Western Front (World War I)

text: By 1917, the size of the British Army on the Western Front had grown to two-thirds of the size of the French force. In April 1917 the BEF began the Battle of Arras. The Canadian Corps and the 5th Division of the First Army, fought the Battle of Vimy Ridge, completing the capture of the ridge and the Third Army to the south achieved the deepest advance since trench warfare began. Later attacks were confronted by German reinforcements defending the area using the lessons learned on the Somme in 1916. British attacks were contained and, according to Gary Sheffield, a greater rate of daily loss was inflicted on the British than in "any other major battle".


title: Western Front (World War I)

text: During the winter of 1916–1917, German air tactics had been improved, a fighter training school was opened at Valenciennes and better aircraft with twin guns were introduced. The result was higher losses of Allied aircraft, particularly for the British, Portuguese, Belgians and Australians who were struggling with outmoded aircraft, poor training and tactics. The Allied air successes over the Somme were not be repeated. During their attack at Arras, the British lost 316 air crews and the Canadians lost 114 compared to 44 lost by the Germans. This became known to the Royal Flying Corps as Bloody April.


title: Western Front (World War I)

text: The same month, the French Commander-in-chief, General Robert Nivelle, ordered a new offensive against the German trenches, promising that it would end the war within 48 hours. The 16 April attack, dubbed the Nivelle Offensive (also known as the Second Battle of the Aisne), would be 1.2 million men strong, preceded by a week-long artillery bombardment and accompanied by tanks. The offensive proceeded poorly as the French troops, with the help of two Russian brigades, had to negotiate rough, upward-sloping terrain in extremely bad weather. Planning had been dislocated by the voluntary German withdrawal to the Hindenburg Line. Secrecy had been compromised and German aircraft gained air superiority, making reconnaissance difficult and in places, the creeping barrage moved too fast for the French troops. Within a week the French suffered 120,000 casualties. Despite the casualties and his promise to halt the offensive if it did not produce a breakthrough, Nivelle ordered the attack to continue into May.


title: Western Front (World War I)

text: On 3 May the weary French 2nd Colonial Division, veterans of the Battle of Verdun, refused orders, arriving drunk and without their weapons. Lacking the means to punish an entire division, its officers did not immediately implement harsh measures against the mutineers. Mutinies occurred in 54 French divisions and 20,000 men deserted. Other Allied forces attacked but suffered massive casualties. Appeals to patriotism and duty followed, as did mass arrests and trials. The French soldiers returned to defend their trenches but refused to participate in further offensive action. On 15 May Nivelle was removed from command, replaced by Pétain who immediately stopped the offensive. The French would go on the defensive for the following months to avoid high casualties and to restore confidence in the French High Command, while the British assumed greater responsibility.


title: Western Front (World War I)

text: On 25 June the first US troops began to arrive in France, forming the American Expeditionary Force. However, the American units did not enter the trenches in divisional strength until October. The incoming troops required training and equipment before they could join in the effort, and for several months American units were relegated to support efforts. In spite of this, however, their presence provided a much-needed boost to Allied morale, with the promise of further reinforcements that could tip the manpower balance towards the Allies.


title: Western Front (World War I)

text: In June, the British launched an offensive in Flanders, in part to take the pressure off the French armies on the Aisne, after the French part of the Nivelle Offensive failed to achieve the strategic victory that had been planned and French troops began to mutiny. The offensive began on 7 June, with a British attack on Messines Ridge, south of Ypres, to retake the ground lost in the First and Second battles in 1914. Since 1915 specialist Royal Engineer tunnelling companies had been digging tunnels under the ridge, and about of explosives had been planted in 21 mines under the German defences. Following several weeks of bombardment, the explosives in 19 of these mines were detonated, killing up to 7,000 German troops. The infantry advance that followed relied on three creeping barrages which the British infantry followed to capture the plateau and the east side of the ridge in one day. German counter-attacks were defeated and the southern flank of the Gheluvelt plateau was protected from German observation.


title: Western Front (World War I)

text: On 11 July 1917, during "Unternehmen Strandfest" (Operation Beachparty) at Nieuport on the coast, the Germans introduced a new weapon into the war when they fired a powerful blistering agent Sulfur mustard (Yellow Cross) gas. The artillery deployment allowed heavy concentrations of the gas to be used on selected targets. Mustard gas was persistent and could contaminate an area for days, denying it to the British, an additional demoralising factor. The Allies increased production of gas for chemical warfare but took until late 1918 to copy the Germans and begin using mustard gas.


title: Western Front (World War I)

text: From 31 July to 10 November the Third Battle of Ypres included the First Battle of Passchendaele and culminated in the Second Battle of Passchendaele. The battle had the original aim of capturing the ridges east of Ypres then advancing to Roulers and Thourout to close the main rail line supplying the German garrisons on the Western front north of Ypres. If successful the northern armies were then to capture the German submarine bases on the Belgian coast. It was later restricted to advancing the British Army onto the ridges around Ypres, as the unusually wet weather slowed British progress. The Canadian Corps relieved the II ANZAC Corps and took the village of Passchendaele on 6 November, despite rain, mud and many casualties. The offensive was costly in manpower for both sides for relatively little gain of ground against determined German resistance but the ground captured was of great tactical importance. In the drier periods, the British advance was inexorable and during the unusually wet August and in the Autumn rains that began in early October, the Germans achieved only costly defensive successes, which led the German commanders in early October to begin preparations for a general retreat. Both sides lost a combined total of over a half million men during this offensive. The battle has become a byword among some British revisionist historians for bloody and futile slaughter, whilst the Germans called Passchendaele "the greatest martyrdom of the war."


title: Western Front (World War I)

text: On 20 November the British launched the first massed tank attack and the first attack using predicted artillery-fire (aiming artillery without firing the guns to obtain target data) at the Battle of Cambrai. The Allies attacked with 324 tanks (with one-third held in reserve) and twelve divisions, advancing behind a hurricane bombardment, against two German divisions. The machines carried fascines on their fronts to bridge trenches and the German tank traps. Special "grapnel tanks" towed hooks to pull away the German barbed wire. The attack was a great success for the British, who penetrated further in six hours than at the Third Ypres in four months, at a cost of only 4,000 British casualties. The advance produced an awkward salient and a surprise German counter-offensive began on 30 November, which drove back the British in the south and failed in the north. Despite the reversal, the attack was seen as a success by the Allies, proving that tanks could overcome trench defences. The Germans realised that the use of tanks by the Allies posed a new threat to any defensive strategy they might mount. The battle had also seen the first mass use of German "Stosstruppen" on the Western front in the attack, who used infantry infiltration tactics to penetrate British defences, bypassing resistance and quickly advancing into the British rear.


title: Western Front (World War I)

text: Following the successful Allied attack and penetration of the German defences at Cambrai, Ludendorff and Hindenburg determined that the only opportunity for German victory lay in a decisive attack along the Western front during the spring, before American manpower became overwhelming. On 3 March 1918, the Treaty of Brest-Litovsk was signed and Russia withdrew from the war. This would now have a dramatic effect on the conflict as 33 divisions were released from the Eastern Front for deployment to the west. The Germans occupied almost as much Russian territory under the provisions of the Treaty of Brest-Litovsk as they did in the Second World War but this considerably restricted their troop redeployment. The Germans achieved an advantage of 192 divisions in the west to the 178 Allied divisions, which allowed Germany to pull veteran units from the line and retrain them as "Stosstruppen" (40 infantry and 3 cavalry divisions were retained for German occupation duties in the east).


title: Western Front (World War I)

text: The Allies lacked unity of command and suffered from morale and manpower problems, the British and French armies were severely depleted and not in a position to attack in the first half of the year, while the majority of the newly arrived American troops were still training, with just six complete divisions in the line. Ludendorff decided on an offensive strategy beginning with a big attack against the British on the Somme, to separate them from the French and drive them back to the channel ports. The attack would combine the new storm troop tactics with over 700 aircraft, tanks and a carefully planned artillery barrage that would include gas attacks.


title: Western Front (World War I)

text: Operation Michael, the first of the German spring offensives, very nearly succeeded in driving the Allied armies apart, advancing to within shelling distance of Paris for the first time since 1914. As a result of the battle, the Allies agreed on unity of command. General Ferdinand Foch was appointed commander of all Allied forces in France. The unified Allies were better able to respond to each of the German drives and the offensive turned into a battle of attrition. In May, the American divisions also began to play an increasing role, winning their first victory in the Battle of Cantigny. By summer, between 250,000 and 300,000 American soldiers were arriving every month. A total of 2.1 million American troops would be deployed on this front before the war came to an end. The rapidly increasing American presence served as a counter for the large numbers of redeployed German forces.


title: Western Front (World War I)

text: In July, Foch began the Second Battle of the Marne, a counter-offensive against the Marne salient which was eliminated by August. The Battle of Amiens began two days later, with Franco-British forces spearheaded by Australian and Canadian troops, along with 600 tanks and 800 aircraft. Hindenburg named 8 August as the "Black Day of the German army." The Italian 2nd Corps, commanded by General Alberico Albricci, also participated in the operations around Reims. German manpower had been severely depleted after four years of war and its economy and society were under great internal strain. The Allies fielded 216 divisions against 197 German divisions. The Hundred Days Offensive beginning in August proved the final straw and following this string of military defeats, German troops began to surrender in large numbers. As the Allied forces advanced, Prince Maximilian of Baden was appointed as Chancellor of Germany in October to negotiate an armistice. Ludendorff was forced out and fled to Sweden. The German retreat continued and the German Revolution put a new government in power. The Armistice of Compiègne was quickly signed, stopping hostilities on the Western Front on 11 November 1918, later known as Armistice Day. The German Imperial Monarchy collapsed when General Groener, the successor to Ludendorff, backed the moderate Social Democratic Government under Friedrich Ebert, to forestall a revolution like those in Russia the previous year.


title: Western Front (World War I)

text: The war along the Western Front led the German government and its allies to sue for peace in spite of German success elsewhere. As a result, the terms of the peace were dictated by France, Britain and the United States, during the 1919 Paris Peace Conference. The result was the Treaty of Versailles, signed in June 1919 by a delegation of the new German government. The terms of the treaty constrained Germany as an economic and military power. The Versailles treaty returned the border provinces of Alsace-Lorraine to France, thus limiting the coal required by German industry. The Saar, which formed the west bank of the Rhine, would be demilitarised and controlled by Britain and France, while the Kiel Canal opened to international traffic. The treaty also drastically reshaped Eastern Europe. It severely limited the German armed forces by restricting the size of the army to 100,000 and disallowing a navy or air force. The navy was sailed to Scapa Flow under the terms of surrender but was later scuttled as a reaction to the treaty.


title: Western Front (World War I)

text: The war in the trenches of the Western Front left tens of thousands of maimed soldiers and war widows. The unprecedented loss of life had a lasting effect on popular attitudes toward war, resulting later in an Allied reluctance to pursue an aggressive policy toward Adolf Hitler. Belgium suffered 30,000 civilian dead and France 40,000 (including 3,000 merchant sailors). The British lost civilian dead, were killed in air and naval attacks, were killed at sea and there were marine deaths. Another 62,000 Belgian, 107,000 British and 300,000 French civilians died due to war-related causes.


title: Western Front (World War I)

text: Germany in 1919 was bankrupt, the people living in a state of semi-starvation and having no commerce with the remainder of the world. The Allies occupied the Rhine cities of Cologne, Koblenz and Mainz, with restoration dependent on payment of reparations. In Germany a Stab-in-the-back myth ("Dolchstoßlegende") was propagated by Hindenburg, Ludendorff and other defeated generals, that the defeat was not the fault of the 'good core' of the army but due to certain left-wing groups within Germany who signed a disastrous armistice; this would later be exploited by nationalists and the Nazi party propaganda to excuse the overthrow of the Weimar Republic in 1930 and the imposition of the Nazi dictatorship after March 1933.


title: Western Front (World War I)

text: France suffered more casualties relative to its population than any other great power and the industrial north-east of the country was devastated by the war. The provinces overrun by Germany had produced 40 percent of French coal and 58 percent of its steel output. Once it was clear that Germany was going to be defeated, Ludendorff had ordered the destruction of the mines in France and Belgium. His goal was to cripple the industries of Germany's main European rival. To prevent similar German attacks in the future, France later built a massive series of fortifications along the German border known as the Maginot Line.


title: Inbreeding

text: Inbreeding is the production of offspring from the mating or breeding of individuals or organisms that are closely related genetically. By analogy, the term is used in human reproduction, but more commonly refers to the genetic disorders and other consequences that may arise from expression of deleterious or recessive traits resulting from incestuous sexual relationships and consanguinity. Animals avoid incest only rarely.


title: Inbreeding

text: Inbreeding results in homozygosity, which can increase the chances of offspring being affected by recessive traits. In extreme cases, this usually leads to at least temporarily decreased biological fitness of a population (called inbreeding depression), which is its ability to survive and reproduce. An individual who inherits such deleterious traits is colloquially referred to as "inbred". The avoidance of expression of such deleterious recessive alleles caused by inbreeding, via inbreeding avoidance mechanisms, is the main selective reason for outcrossing. Crossbreeding between populations sometimes has positive effects on fitness-related traits, but also sometimes leads to negative effects known as outbreeding depression. However, increased homozygosity increases probability of fixing beneficial alleles and also slightly decreases probability of fixing deleterious alleles in population. Inbreeding can result in purging of deleterious alleles from a population through purifying selection.


title: Inbreeding

text: Inbreeding is a technique used in selective breeding. For example, in livestock breeding, breeders may use inbreeding when trying to establish a new and desirable trait in the stock and for producing distinct families within a breed, but will need to watch for undesirable characteristics in offspring, which can then be eliminated through further selective breeding or culling. Inbreeding also helps to ascertain the type of gene action affecting a trait. Inbreeding is also used to reveal deleterious recessive alleles, which can then be eliminated through assortative breeding or through culling. In plant breeding, inbred lines are used as stocks for the creation of hybrid lines to make use of the effects of heterosis. Inbreeding in plants also occurs naturally in the form of self-pollination.


title: Inbreeding

text: Offspring of biologically related persons are subject to the possible effects of inbreeding, such as congenital birth defects. The chances of such disorders are increased when the biological parents are more closely related. This is because such pairings have a 25% probability of producing homozygous zygotes, resulting in offspring with two recessive alleles, which can produce disorders when these alleles are deleterious. Because most recessive alleles are rare in populations, it is unlikely that two unrelated marriage partners will both be carriers of the same deleterious allele; however, because close relatives share a large fraction of their alleles, the probability that any such deleterious allele is inherited from the common ancestor through both parents is increased dramatically. For each homozygous recessive individual formed there is an equal chance of producing a homozygous dominant individual — one completely devoid of the harmful allele. Contrary to common belief, inbreeding does not in itself alter allele frequencies, but rather increases the relative proportion of homozygotes to heterozygotes; however, because the increased proportion of deleterious homozygotes exposes the allele to natural selection, in the long run its frequency decreases more rapidly in inbred populations. In the short term, incestuous reproduction is expected to increase the number of spontaneous abortions of zygotes, perinatal deaths, and postnatal offspring with birth defects. The advantages of inbreeding may be the result of a tendency to preserve the structures of alleles interacting at different loci that have been adapted together by a common selective history.


title: Inbreeding

text: Malformations or harmful traits can stay within a population due to a high homozygosity rate, and this will cause a population to become fixed for certain traits, like having too many bones in an area, like the vertebral column of wolves on Isle Royale or having cranial abnormalities, such as in Northern elephant seals, where their cranial bone length in the lower mandibular tooth row has changed. Having a high homozygosity rate is problematic for a population because it will unmask recessive deleterious alleles generated by mutations, reduce heterozygote advantage, and it is detrimental to the survival of small, endangered animal populations. When deleterious recessive alleles are unmasked due to the increased homozygosity generated by inbreeding, this can cause inbreeding depression.


title: Inbreeding

text: There may also be other deleterious effects besides those caused by recessive diseases. Thus, similar immune systems may be more vulnerable to infectious diseases (see Major histocompatibility complex and sexual selection).


title: Inbreeding

text: Inbreeding history of the population should also be considered when discussing the variation in the severity of inbreeding depression between and within species. With persistent inbreeding, there is evidence that shows that inbreeding depression becomes less severe. This is associated with the unmasking and elimination of severely deleterious recessive alleles. However, inbreeding depression is not a temporary phenomenon because this elimination of deleterious recessive alleles will never be complete. Eliminating slightly deleterious mutations through inbreeding under moderate selection is not as effective. Fixation of alleles most likely occurs through Muller's ratchet, when an asexual population's genome accumulates deleterious mutations that are irreversible.


title: Inbreeding

text: Despite all its disadvantages, inbreeding can also have a variety of advantages, such as ensuring a child produced from the mating contains, and will pass on, a higher percentage of its mother/father's genetics, reducing the recombination load, and allowing the expression of recessive advantageous phenotypes. Some species with a Haplodiploidy mating system depend on the ability to produce sons to mate with as a means of ensuring a mate can be found if no other male is available. It has been proposed that under circumstances when the advantages of inbreeding outweigh the disadvantages, preferential breeding within small groups could be promoted, potentially leading to speciation.


title: Inbreeding

text: Autosomal recessive disorders occur in individuals who have two copies of an allele for a particular recessive genetic mutation. Except in certain rare circumstances, such as new mutations or uniparental disomy, both parents of an individual with such a disorder will be carriers of the gene. These carriers do not display any signs of the mutation and may be unaware that they carry the mutated gene. Since relatives share a higher proportion of their genes than do unrelated people, it is more likely that related parents will both be carriers of the same recessive allele, and therefore their children are at a higher risk of inheriting an autosomal recessive genetic disorder. The extent to which the risk increases depends on the degree of genetic relationship between the parents; the risk is greater when the parents are close relatives and lower for relationships between more distant relatives, such as second cousins, though still greater than for the general population.


title: Inbreeding

text: Children of parent-child or sibling-sibling unions are at an increased risk compared to cousin-cousin unions. Inbreeding may result in a greater than expected phenotypic expression of deleterious recessive alleles within a population. As a result, first-generation inbred individuals are more likely to show physical and health defects, including:


title: Inbreeding

text: The isolation of a small population for a period of time can lead to inbreeding within that population, resulting in increased genetic relatedness between breeding individuals. Inbreeding depression can also occur in a large population if individuals tend to mate with their relatives, instead of mating randomly.


title: Inbreeding

text: Due to higher prenatal and postnatal mortality rates, some individuals in the first generation of inbreeding will not live on to reproduce. Over time, with isolation, such as a population bottleneck caused by purposeful (assortative) breeding or natural environmental factors, the deleterious inherited traits are culled.


title: Inbreeding

text: Island species are often very inbred, as their isolation from the larger group on a mainland allows natural selection to work on their population. This type of isolation may result in the formation of race or even speciation, as the inbreeding first removes many deleterious genes, and permits the expression of genes that allow a population to adapt to an ecosystem. As the adaptation becomes more pronounced, the new species or race radiates from its entrance into the new space, or dies out if it cannot adapt and, most importantly, reproduce.


title: Inbreeding

text: The reduced genetic diversity, for example due to a bottleneck will unavoidably increase inbreeding for the entire population. This may mean that a species may not be able to adapt to changes in environmental conditions. Each individual will have similar immune systems, as immune systems are genetically based. When a species becomes endangered, the population may fall below a minimum whereby the forced interbreeding between the remaining animals will result in extinction.


title: Inbreeding

text: Natural breedings include inbreeding by necessity, and most animals only migrate when necessary. In many cases, the closest available mate is a mother, sister, grandmother, father, brother, or grandfather. In all cases, the environment presents stresses to remove from the population those individuals who cannot survive because of illness.


title: Inbreeding

text: There was an assumption that wild populations do not inbreed; this is not what is observed in some cases in the wild. However, in species such as horses, animals in wild or feral conditions often drive off the young of both sexes, thought to be a mechanism by which the species instinctively avoids some of the genetic consequences of inbreeding. In general, many mammal species, including humanity's closest primate relatives, avoid close inbreeding possibly due to the deleterious effects.


title: Inbreeding

text: Although there are several examples of inbred populations of wild animals, the negative consequences of this inbreeding are poorly documented. In the South American sea lion, there was concern that recent population crashes would reduce genetic diversity. Historical analysis indicated that a population expansion from just two matrilineal lines was responsible for most of the individuals within the population. Even so, the diversity within the lines allowed great variation in the gene pool that may help to protect the South American sea lion from extinction.


title: Inbreeding

text: In lions, prides are often followed by related males in bachelor groups. When the dominant male is killed or driven off by one of these bachelors, a father may be replaced by his son. There is no mechanism for preventing inbreeding or to ensure outcrossing. In the prides, most lionesses are related to one another. If there is more than one dominant male, the group of alpha males are usually related. Two lines are then being "line bred". Also, in some populations, such as the Crater lions, it is known that a population bottleneck has occurred. Researchers found far greater genetic heterozygosity than expected. In fact, predators are known for low genetic variance, along with most of the top portion of the trophic levels of an ecosystem. Additionally, the alpha males of two neighboring prides can be from the same litter; one brother may come to acquire leadership over another's pride, and subsequently mate with his 'nieces' or cousins. However, killing another male's cubs, upon the takeover, allows the new selected gene complement of the incoming alpha male to prevail over the previous male. There are genetic assays being scheduled for lions to determine their genetic diversity. The preliminary studies show results inconsistent with the outcrossing paradigm based on individual environments of the studied groups.


title: Inbreeding

text: In Central California, sea otters were thought to have been driven to extinction due to over hunting, until a small colony was discovered in the Point Sur region in the 1930s. Since then, the population has grown and spread along the central Californian coast to around 2,000 individuals, a level that has remained stable for over a decade. Population growth is limited by the fact that all Californian sea otters are descended from the isolated colony, resulting in inbreeding.


title: Inbreeding

text: Cheetahs are another example of inbreeding. Thousands of years ago, the cheetah went through a population bottleneck that reduced its population dramatically so the animals that are alive today are all related to one another. A consequence from inbreeding for this species has been high juvenile mortality, low fecundity, and poor breeding success.


title: Inbreeding

text: In a study on an island population of song sparrows, individuals that were inbred showed significantly lower survival rates than outbred individuals during a severe winter weather related population crash. These studies show that inbreeding depression and ecological factors have an influence on survival.


title: Inbreeding

text: A measure of inbreeding of an individual A is the probability "F"(A) that both alleles in one locus are derived from the same allele in an ancestor. These two identical alleles that are both derived from a common ancestor are said to be identical by descent. This probability F(A) is called the "coefficient of inbreeding".


title: Inbreeding

text: Another useful measure that describes the extent to which two individuals are related (say individuals A and B) is their coancestry coefficient f(A,B), which gives the probability that one randomly selected allele from A and another randomly selected allele from B are identical by descent. This is also denoted as the kinship coefficient between A and B.


title: Inbreeding

text: A particular case is the self-coancestry of individual A with itself, f(A,A), which is the probability that taking one random allele from A and then, independently and with replacement, another random allele also from A, both are identical by descent. Since they can be identical by descent by sampling the same allele or by sampling both alleles that happen to be identical by descent, we have f(A,A) = 1/2 + F(A)/2.


title: Inbreeding

text: Both the inbreeding and the coancestry coefficients can be defined for specific individuals or as average population values. They can be computed from genealogies or estimated from the population size and its breeding properties, but all methods assume no selection and are limited to neutral alleles.


title: Inbreeding

text: There are several methods to compute this percentage. The two main ways are the path method and the tabular method.


title: Inbreeding

text: Breeding in domestic animals is primarily assortative breeding (see selective breeding). Without the sorting of individuals by trait, a breed could not be established, nor could poor genetic material be removed.


title: Inbreeding

text: Homozygosity is the case where similar or identical alleles combine to express a trait that is not otherwise expressed (recessiveness). Inbreeding exposes recessive alleles through increasing homozygosity.


title: Inbreeding

text: Breeders must avoid breeding from individuals that demonstrate either homozygosity or heterozygosity for disease causing alleles. The goal of preventing the transfer of deleterious alleles may be achieved by reproductive isolation, sterilization, or, in the extreme case, culling. Culling is not strictly necessary if genetics are the only issue in hand. Small animals such as cats and dogs may be sterilized, but in the case of large agricultural animals, such as cattle, culling is usually the only economic option.


title: Inbreeding

text: The issue of casual breeders who inbreed irresponsibly is discussed in the following quotation on cattle: