text: People reported that trains and houses were being searched for 'Anastasia Romanov' by soldiers and secret police. When she was put in prison for a short time at Perm in 1918, Princess Helena Petrovna, the wife of Anastasia's distant cousin, Prince Ioann Konstantinovich of Russia, said that a guard took a girl who called herself Anastasia Romanova to her cell and asked her if the girl was the Tsar's daughter. When she did not recognize the girl, the guard took her away. Others in Perm later said that they saw Anastasia, her mother and sisters in Perm after they were killed, but this was only a rumor. Surprisingly, the rumors that had started to hide the fact that the family was dead helped the rumors that they were alive. A few days after they had been killed, the German government sent telegrams to Russia asking for "the safety of the princesses of German blood". Russia had signed a peace treaty with the Germans and did not want to tell them that the women were dead. Instead, they told them they had been moved to a safer place. This could have been why the 'Perm stories' began.


title: Grand Duchess Anastasia Nikolaevna of Russia

text: Another time, eight people said that they saw a young woman being captured at a railway station at Siding 37 in September 1918 after trying to escape. These people were Maxim Grigoyev, Tatiana Sitnikova and her son Fyodor Sitnikov, Ivan Kuklin and Matrina Kuklina, Vassily Ryabov, Ustinya Varankina, and Dr. Pavel Utkin. Some of these people said that the girl was Anastasia when they saw photographs of the grand duchess by White Russian Army investigators. Dr. Pavel Utkin also told the investigators that the girl, whom he had helped in Perm when she was hurt, had said, "I am the daughter of the ruler, Anastasia." During that time, there were similar stories of young people in Russia saying that they were Romanovs who had escaped. Boris Soloviev, the husband of Rasputin's daughter Maria, defrauded many important Russian families by asking for money for a Romanov to escape to China. Soloviev was helped by young women who pretended to be one of the grand duchesses to help trick the families.


text: Some suggest that there might have been a way for a guard to save anyone in the family who still lived. Yakov Yurovsky ordered the guards to come to his office and give him the things they had stolen after the murder. At that time, it is said that there was a short time when the killed bodies were left in the truck and in the basement of the house. Some guards who had not joined in the murders and had felt sorry for the grand duchesses were left in the basement with the bodies.


text: There were also stories from Bulgaria that Anastasia and her brother were still alive. In 1953, Peter Zamiatkin told a 16-year-old person being treated at a hospital that he had taken Anastasia and Alexei to the village where he was born near Odessa. He said he was a member of the guard of the Romanovs, and that the Tsar had asked him to do this. Zamiatkin said that after the rest of the family had been killed, he escaped with the children on a ship. "Anastasia" and "Alexei" lived under false names in the Bulgarian town of Gabarevo. The Bulgarian "Anastasia" called herself Eleonora Albertovna Kruger. She died in 1954.


text: In 1991, the place where the Imperial family and their servants were supposedly buried as found in the woods outside Yekaterinburg. It had actually been found almost ten years earlier, but had been kept hidden by the people who discovered it. They did not want the Communists, who still ruled Russia at that time, to know where the grave was. The grave only had nine bodies instead of 11. DNA and studies on their skeletons showed that they were the bodies of Tsar Nicholas II, his wife, and three of the Grand Duchesses (Olga, Tatiana, and Maria). The other remains had different DNA. They were the bodies of the family's doctor (Yevgeny Botkin), valet (Alexei Trupp), cook (Ivan Kharitonov) and Alexandra's maid (Anna Demidova). Dr. William Maples decided that the Tsarevitch Alexei and Anastasia's bodies were missing. Russian scientists did not agree with this. They claimed that it was the body of Maria was missing, not Anastasia's. The Russians used a computer program to compare photos of Anastasia with the skulls from the grave. When some of the pieces of bone in the skulls were missing, they guessed how long or wide it was instead. American scientists thought this way of studying the bodies was wrong.


text: American scientists thought the missing body was Anastasia's. This was because none of the female skeletons showed signs that it was not fully grown yet. The remains of the Imperial Family were buried in 1998. At that time, a body that measured about 5 feet, 7 inches (170 cm) was buried as the body of Anastasia. Photographs of her standing next to her sisters six months before she died show that Anastasia was a few inches shorter than all of them.


text: The "Yurovsky Note" showed that two of the bodies were taken from the main grave and burned secretly to hide the burials of the Imperial family. However, people could not find the place where the bodies were burnt for many years. However, on 23 August 2007, a Russian archaeologist declared that he had found two burned skeletons near Yekaterinburg, at a place which seemed to match what was described in Yurovsky's writings. The archaeologists said that the bones were from a boy who was about 10 to 13, and a young woman who was between 18 and 23 years old. Anastasia was 17 years and one month old when she was killed; Maria was 19 years, one month old, and Alexei was just two weeks before his fourteenth birthday. Anastasia's older sisters, Olga and Tatiana, were 22 and 23 when they died. They used metal detectors to find the bones.


text: Many international laboratories such as the Armed Forces DNA Identification Laboratory and Medical University of Innsbruck did DNA tests. They proved that the remains were from the body of Tsarevich Alexei and one of his sister. They agreed that everyone in the family, including Anastasia, died in 1918. All the parents and children has his or her own special DNA.


text: In 2000, Anastasia and her family were canonized as passion bearers by the Russian Orthodox Church. In 1981, they had already been canonized by the Russian Orthodox Church Abroad as holy martyrs. The bodies of Tsar Nicholas II, Tsarina Alexandra, and three of their daughters were buried in the St. Catherine Chapel at St. Peter and Paul Cathedral in St. Petersburg on 17 July 1998. This was 80 years after they had been murdered.


text: The stories of how Anastasia might have escaped became the subject of theatrical and television movies. The earliest, made in 1928, was called "Clothes Make the Woman". The story was about a woman who acts the character of Anastasia in a Hollywood movie, and is later recognized by the Russian soldier who saved her.


text: In 1956, a movie called "Anastasia" was made. Ingrid Bergman acted Anna Anderson, Yul Brynner was General Bounine (a fictional character based on several real men), and Helen Hayes as the Dowager Empress Marie, Anastasia's grandmother. The movie is about a woman from an asylum who came to Paris in 1928 and was captured by some Russian émigrés who use her so that they can fool Anastasia's grandmother into thinking Anderson actually is her granddaughter. This is because they want to get a Tsarist fortune. After some time, they begin wondering if "Madame A. Anderson" really is the missing Grand Duchess.


text: In 1986, NBC began a mini-series inspired by a book published in 1983 by Peter Kurth called "Anastasia: The Riddle of Anna Anderson". The movie, "", was a series with two parts. It began with the young Anastasia Nicholaievna and her family being sent to Yekaterinburg, where they are killed by Bolshevik soldiers. The story then moves to 1923, saying that Anna Anderson is Anastasia. Amy Irving was the actress for Anna Anderson.


text: The most recent movie is 1997's "Anastasia". This was an animated musical adaptation of the story of Anastasia's fictional (not real) escape from Russia and how she tried to be recognized. The movie often used wrong historical facts.


text: In "The Romanov Prophecy," a 2004 novel by Steve Berry, Anastasia and Alexei are saved by guards and taken away to the United States. There, they live under false names with a family paid by Felix Yusupov. In the novel, both children died in the 1920s because they became sick. However, before they died, Alexei married and had a son.


title: Vatican City

text: Vatican City (; officially Vatican City State, ) is an independent sovereign state and the smallest country in the world by size, at 0.49 km². Its territory is completely surrounded by Italy and it is only one of three countries in the world that are enclaves of another country (the others being San Marino, also in Italy, and Lesotho in southern Africa). Also, it is the only country in the world that is an enclave of a city, as all of the land around it is part of Rome, the capital of Italy. The Vatican City is a city-state, because all its territory is urban and built-up.


title: Vatican City

text: The Vatican City is the headquarters of the Roman Catholic Church and its government, the Holy See. Its head of state is the Pope which is, religiously speaking, the Bishop of Rome and head of the Roman Catholic Church. The current Pope, Pope Francis, former cardinal Jorge Mario Bergoglio, was elected on 13 March 2013.


title: Vatican City

text: Established on 11 February 1929 with the Lateran Agreement ("Patti Lateranensi") signed by Benito Mussolini and Pope Pius XI, the Vatican City is also important for its culture and art. The Vatican's masterpieces are very well known in the world: St. Peter's Square, St. Peter's Basilica, the Sistine Chapel, the Vatican Museums and the Apostolic Palace, where the Pope lives. There are also hundreds of other sculptures and pictures.


title: Vatican City

text: The Pope used to rule the Papal States, which included most of Italy. Catholic popes had generally tried to stop Italy from becoming one country because they feared they would lose their control of at least one of the Papal States. In 1861 Italy was unified under the King of Savoy, but Rome and Latium remained unconquered. On September 20, 1870 Italian troops invaded. Rome became capital of the new kingdom.


title: Vatican City

text: The Pope claimed he was a prisoner of the Italian state and excommunicated all the people who helped invade the Papal state. This stopped Catholics from taking part in public life under Catholic government.


title: Vatican City

text: In 1929 Benito Mussolini, decided to sign an agreement with the Holy See, called the Lateran Treaty, which created the Vatican State. Another treaty gave the Vatican money each year to compensate for the lost territories.


title: Vatican City

text: The government structure is theocracy with the pontifical leader being the highest authority. The pope is elected by the College of Cardinals which can lead the Roman Catholic Church and the city-state itself. The Pope also holds the title of "Bishop of Rome".


title: Vatican City

text: Vatican City has a population of 453 people, and 246 of them are citizens. The citizens of the Vatican include the Pope, all the cardinals, all the ambassadors (who are called nuncios) and other diplomats, all the Swiss Guards, and other important people. Also, there are 372 Vatican citizens who live in other countries, including cardinals and nuncios. Vatican citizenship cannot be passed to children and spouses; and, except for the Pope and cardinals, Vatican citizenship is lost when the term of office comes to an end, for the Swiss Guards, nuncios and diplomats, and other people working for the Vatican.


title: Vatican City

text: The Vatican does not have a law declaring an official language. Italian is the main language used. The Holy See's official language is Latin.


title: Vatican City

text: The official religion of the Vatican is Roman Catholic Christianity, and because the state is ruled by a Pope, it is a theocracy.


title: Photography

text: Photography is a way of making a picture using a camera. A person who makes pictures using a camera is called a "photographer". A picture made using a camera is called a photograph or photo. Photography became popular in the middle 19th century with Daguerreotype. Later wet plate and dry plate methods were invented. Most photography in the 20th century was on photographic film and most in the 21st uses digital cameras.


title: Photography

text: A camera is, in its simplest form, a box with a hole in its front. There is a special piece of glass in front of the hole called a lens. To take a photograph, the lens makes a small picture of the object inside the camera, which it does by focusing light. A lens in a camera works like a lens in glasses (spectacles) or a magnifying glass. One type of camera called the Pinhole camera has no lens but uses a very small hole to focus light.


title: Photography

text: To make a photograph with a camera, the "shutter release" button is pressed. Pressing the button opens the "shutter". The shutter is like a door. It covers the hole in the camera box. The shutter is behind the lens. When the shutter is closed no light can enter the camera box. When the shutter is open light can enter the camera. When the button is pressed the shutter opens and then closes. This happens very fast. The amount of time the shutter stays open for is called the "shutter speed". The shutter speed can change between 1/1000th of a second (0.001 s) to a few seconds. Normally the time taken for the shutter to open and close is far less than 1 second.


title: Photography

text: The photograph in a camera may be made on film or, if it is a digital camera, on an electronic sensor.


title: Photography

text: The picture the lens makes is recorded on photographic film. Film is placed inside the camera box. Light coming through the lens, aperture and open shutter shines on the film. Photographic film is coated with chemicals that react when light shines on it. Letting light shine on the film is called "exposing" the film.


title: Photography

text: There are many different types of photographic film. There are films for taking colour photographs and films for taking black and white photographs. There are different sizes of film. The most common size is "35 mm". It is called 35 mm because the width of the film is 35 millimetres.


title: Photography

text: Another difference between films is how sensitive they are to light. Films have a number, called an "ISO number", which tells how fast a film reacts when light shines on it.


title: Photography

text: Once the film has been exposed it is "processed". Processing has to be done in total darkness or the film will be exposed too much and the picture will be lost. Processing stops the film reacting to light any more. After the film has been processed the picture can be seen on the film.


title: Photography

text: A photographic "print" is a photograph made on paper. A light sensitive paper is used. The picture on the film is placed in an "enlarger". An enlarger is a machine that shines light through the film and makes a bigger picture on the light sensitive paper. A chemical reaction happens in the paper, which turns the areas hit with light black when the paper is 'developed'. (The more light, the darker the area.) "Developing" makes the picture appear on the paper – now it is a photograph. Then the paper is put into other chemicals that make it not sensitive to light any more. This is called "fixing". Last, the paper is washed so that there are no more chemicals on it and then dried. Then it is finished.


title: Photography

text: Digital photography uses a digital camera. Sometimes it is called "digital imaging". Like other cameras a digital camera has a lens, aperture, and shutter. The picture the lens makes is recorded by a light-sensitive electronic sensor. A digital camera does not use photographic film to record a picture. Digital photographs are stored in storage devices such as SD cards. They can later be transferred to a computer. Paper prints can also be made from digital pictures. Digital cameras are also not expensive to use, as there is no film to buy.


title: Photography

text: One of the most important things when taking a photograph is focusing the lens. If the lens is not focused well, the photograph will be blurry. Autofocus cameras focus automatically when the shutter release is pressed. There are also "manual" focus cameras (usually older ones).


title: Photography

text: Three other things are important when taking a photograph. These control how bright or dark the photograph will be. The brighter you have it the more transparent the picture comes out, if you have it to bright the whole screen can turn out to be all white, if the camera settings are set to be to dark, well, then the picture will come out to dark. So it really depends on how you want the picture, some cameras automatically come in with the setting at 50%, this is most recommended if you want to take a normal picture, but if you want to adjust the settings, it is recommended to keep it between 45% and 75%.


title: Photography

text: A slower shutter speed, a bigger aperture, and faster film/higher ISO sensor all make a brighter picture. A faster shutter speed, a smaller aperture, and a slower film/lower ISO sensor all make a darker picture. A good picture is not too bright and not too dark. When it is too bright it would be called "overexposed". An automatic camera changes these things by itself when the shutter release is pressed.


title: Tebibyte

text: A tebibyte (TiB) is a unit of measurement in computers and similar electronic devices. Tebibytes hold 1024 gibibytes (GiB) or 1,099,511,627,776 bytes. Some people incorrectly call this number of bytes a terabyte, which is actually one trillion bytes, or 1000 gigabytes (GB).


title: Volcanoes of South America

text: The volcanoes of South America are part of the Pacific Ring of Fire. Most of them are along the backbone of the Andes.


title: Volcanoes of South America

text: The Andes, together with the volcanoes, has been produced by the movement of the Americas towards the west. This has been happening for a long time, certainly 60 million years or more. This continental drift leads to subduction of oceanic plates beneath the continental plates of the land mass. In turn, this produced the mountain ranges (orogeny) and the volcanic activity. A rather different cause is at work on the Galápagos Islands. There, a hotspot under the plate caused the islands and their volcanoes to rise up from the sea floor.


title: Volcanoes of South America

text: The country of Bolivia hosts numerous active and extinct volcanoes across its territory. The active volcanoes are located in western Bolivia where they make up the western limit of the Altiplano plateau. Many of the active volcanoes are international mountains shared with Chile. Apart from Andean volcanoes, Bolivia has the remnants of ancient volcanoes around the Precambrian Guaporé Shield in the eastern part of the country.


title: Volcanoes of South America

text: Earthquake activity in Chile is related to subduction of the Nazca Plate to the east. Chile notably holds the record for the largest earthquake ever recorded, the 1960 Valdivia earthquake. Villarrica, one of Chile's most active volcanoes, rises above Villarrica Lake and the town of Villarrica. It is the westernmost of three large stratovolcanoes that trend perpendicular to the Andean chain. A 6-km wide caldera formed during the late Pleistocene, >0.9 million years ago.


title: Volcanoes of South America

text: The Llaima Volcano is one of the largest and most active volcanoes in Chile. It is situated 82 km northeast of Temuco and 663 km southeast of Santiago, within the borders of Conguillío National Park. Llaima’s activity has been documented since the 17th century, and consists of several separate episodes of moderate explosive eruptions with occasional lava flows. The last major eruption occurred in 1994.


title: Volcanoes of South America

text: Chile has experienced numerous volcanic eruptions from 60 volcanoes, including Llaima Volcano and the Chaitén Volcano.


title: Volcanoes of South America

text: Lascar Volcano is a stratovolcano, the most active volcano of the northern Chilean Andes. The largest eruption of Lascar took place about 26,500 years ago. Frequent small-to-moderate explosive eruptions have been recorded from Lascar in historical times since the mid-19th century.


title: Volcanoes of South America

text: Villarrica, is one of only five volcanoes worldwide known to have an active lava lake inside its crater. The volcano usually generates strombolian eruptions, with ejection of fiery pyroclasts and lava flows. Melting of snow and glacier ice as well as rainfalls often cause massive lahars (mud and debris flows), such as during the eruptions of 1964 and 1971.


title: Volcanoes of South America

text: Cotopaxi is a stratovolcano in the Andes Mountains, about south of Quito, Ecuador, South America. It is the second highest summit in the country, reaching a height of . Some consider it the world's highest active volcano. Others give this status to the much higher Llullaillaco, which most recently erupted in 1877 and is one of Ecuador's most active volcanoes. Since 1738, Cotopaxi has erupted more than 50 times, resulting in the creation of numerous valleys formed by lahars (mudflows) around the volcano.


title: Volcanoes of South America

text: In October 1999, Pichincha Volcano erupted in Quito and covered the city with several inches of ash. Before that, the last major eruptions were in 1553 and in 1660, when about 30 cm of ash fell on the city.


title: Volcanoes of South America

text: At 5230 meters, Sangay Volcano is an active [stratovolcano] in central Ecuador. It is one of the highest active volcanoes in the world and one of Ecuador's most active ones, erupting three times in recorded history. It shows mostly Strombolian activity. The most recent eruption, which started in 1934, is still ongoing. Geologically, Sangay marks the southern bound of the Northern Volcanic Zone, and its position straddling two major pieces of crust accounts for its high level of activity. Sangay's approximately 500,000 year old history is one of instability. Two previous versions of the mountain were destroyed in massive flank collapses, evidence of which still litters its surroundings today. Sangay is one of two active volcanoes located in the namesake Sangay National Park, the other being Tungurahua to the north. The Park has been listed as a UNESCO World Heritage Site since 1983.


title: Volcanoes of South America

text: Reventador is an active stratovolcano which lies in the eastern Andes of Ecuador. Since 1541 it has erupted over 25 times with most recent eruption in 2009, but the largest historical eruption occurred in 2002. During that eruption the plume from the volcano reached a height of 17 km and pyroclastic flows went up to 7 km from the cone. On March 30, 2007, the mountain spewed ash again. The ash reached a height of about two miles (3 km, 11,000 ft). No injuries or damages have been reported.


title: Volcanoes of South America

text: The Galápagos Islands are an isolated set of volcanoes, consisting of shield volcanoes and lava plateaus, west of Ecuador. They are driven by the Galápagos hotspot, and are between 4.2 million and 700,000 years of age. The largest island, Isabela Island, consists of six coalesced shield volcanoes, each delineated by a large summit caldera. Española, the oldest island, and Fernandina, the youngest, are also shield volcanoes, as are most of the other islands in the chain. The Galápagos Islands are perched on a large lava plateau known as the Galápagos Platform. This platform creates a shallow water depth of at the base of the islands, which stretch over a -long diameter.


title: Volcanoes of South America

text: Since Charles Darwin's famous visit to the islands in 1835, there have been over 60 recorded eruptions in the islands, from six different shield volcanoes. Of the 21 emergent volcanoes, 13 are considered active.


title: Volcanoes of South America

text: Blue Hill is a shield volcano on the south western part of Isabela Island in the Galápagos Islands and is one of the most active in the Galapagos, with the last eruption between May and June 2008. The Galápagos islands are geologically young for such a big chain, and the pattern of their rift zones follows one of two trends, one north-northwest, and one east-west. The composition of the lavas of the Galápagos shields are strikingly similar to those of the Hawaiian volcanoes.


title: Volcanoes of South America

text: How exactly the islands were formed remains a geological mystery, although several theories have been fronted. Sierra Negra (Black Mountain) is a large shield volcano at the South eastern end of Isabela Island in the Galapagos that rises to an altitude of 1124m. It coalesces with the volcanoes Cerro Azul to the west and Alcedo to the north. The volcano is one of the most active in the Galapagos, with the last eruption starting on 22 October 2005 and lasting until 30 October 2005.


title: Volcanoes of South America

text: Alcedo Volcano is one of the six coalescing shield volcanoes that make up Isabela Island in the Galapagos. The remote location of the volcano has meant that even the most recent eruption in 1993 was not recorded until two years later.


title: Volcanoes of South America

text: Fernandina Island (formerly known in English as Narborough Island, after John Narborough) is the third largest, and youngest, island of the Galápagos Islands. Like the others, the island was formed by the Galápagos hotspot. The island is an active shield volcano that has been erupting since April 11, 2009.


title: Volcanoes of South America

text: Sabancaya is an active stratovolcano in the Andes of southern Peru, about northwest of Arequipa. It is the most active volcano in Peru with an ongoing eruption that started in August 2014 and is continuing.


title: Volcanoes of South America

text: Ubinas is another active volcano in southern Peru with an ongoing eruption. Until 2006, this stratovolcano had not erupted for about 40 years. On April 23, 2006, Peru declared a state of emergency in towns near the volcano. On April 28, 2014, Despite a recent decline in earthquakes, Ubinas Volcano erupted an ash plume on April 28, 2014.


title: Menstrual cycle

text: The menstrual cycle is a process that adult women can go through. The menstrual cycle for a woman will repeat every 28 days while they are not pregnant. During this time, the women's ovaries create a mature ovum (egg). Then the woman's body prepares for pregnancy by thickening the walls of the uterus. If the woman does not become pregnant during this time, the egg and the lining of the uterus come out of the woman's body during menstruation.


title: Menstrual cycle

text: The menstrual cycle process is controlled by four major hormones: FSH (follicle stimulating hormone); LH (luteinising hormone); estrogen; and progesterone. These hormones prepare the uterus to receive a fertilized egg and control its development.


title: Menstrual cycle

text: The menstrual cycle has three stages: the Follicular stage, Ovulation, and the Luteal (or premenstrual) stage. The cycle will stop if the woman gets pregnant (if a fertilized egg implants itself into the lining of the uterus).


title: Menstrual cycle

text: This stage is the start of the menstrual cycle, and is counted as day one of the cycle. This stage starts when the amount of progesterone and estrogen in a woman's blood drop. This causes the endometrium - the thick lining of the uterus - to leave the woman's body through menstruation. It will appear as bleeding from the vagina. This stage lasts from 4–6 days.


title: Menstrual cycle

text: At the start of this stage, the pituitary gland will begin to release more FSH. This will continue for 3-4 days. The FSH makes several follicles grow in one of the ovaries. Each follicle contains an immature ova (egg). These follicles create estrogen.


title: Menstrual cycle

text: Usually, the amount of FSH in the body peaks during the third or fourth day of menstruation. All but one of the follicles dies off. The one that is left releases even more estrogen. Once again, the lining of the uterus thickens. Near the end of the stage, a woman's estrogen levels peak. This causes the pituitary gland to release LH, which also peaks at this time.


title: Menstrual cycle

text: Ovulation happens roughly every 14 days. This is when the mature egg is released into the oviduct (or fallopian tube) ready for fertilisation.


title: Menstrual cycle

text: Ovulation happens if there is both a rise in estrogen and a peak in LH at the end of the follicular stage. The rising levels of LH make the ovum mature. The follicle that contains the ovum swells and breaks open. (In the next stage, the leftover cells of the follicle turn into an important structure called the corpus luteum.) The ovum is released into the Fallopian tube.


title: Menstrual cycle

text: The follicle cells that used to hold the ovum now release progesterone into the body. This causes the endometrium to get even thicker.


title: Menstrual cycle

text: If an ovum is going to be fertilized, it happens during this step. A woman becomes pregnant when a man's sperm fertilizes one of her ova, which then plants itself into the lining of the uterus.


title: Menstrual cycle

text: If the ovum is fertilized during Ovulation, it will become a zygote. It will start to copy itself over and over again through mitosis. It will also move from the ovarian duct into the uterus. The levels of estrogen and progesterone in the body remain high. The zygote grows into an embryo and implants itself into the endometrium tissue of the uterus. This forms a placenta, which starts to mature.


title: Menstrual cycle

text: After fertilization, the menstrual cycle stops so the embryo can continue to mature for the next 9 months. Progesterone and estrogen levels will stay high until the fetus is ready to be birthed.


title: Menstrual cycle

text: Eventually, after giving birth, a woman's menstrual cycle will return to the way it was before she got pregnant.


title: Menstrual cycle

text: Until around day 22, estrogen levels increase a little. However, after day 22, the corpus luteum stops making progesterone, and the levels of both progesterone and estrogen in the body start to drop. The amount of progesterone and estrogen in the body are at their lowest around the 28th day of the menstrual cycle.


title: Asteroid

text: An asteroid is a space rock. It is a small object in the Solar System that travels around the Sun. It is like a planet but smaller. They range from very small (smaller than a car) to 600 miles (1000 km) across. A few asteroids have asteroid moon.


title: Asteroid

text: The name "asteroid" means "like a star" in the ancient Greek language. Asteroids may look like small stars in the sky, but they really do move around the Sun, while stars only seem to move because the Earth spins. Like planets, asteroids do not make their own light. Because of this, some people think "asteroids" is not a good name, and think that the name "planetoid" ("like a planet") would be a better name.


title: Asteroid

text: Giuseppe Piazzi found the first asteroid, in 1801. He called it Ceres, and it is the biggest object in the asteroid belt. Others, like Juno, Pallas, and Vesta were found later. In the 1850s so many had been found, that they were numbered by a Minor planet designation starting with 1 Ceres. Today, astronomers using computerized telescopes find thousands of asteroids every month. Asteroid impact prediction is one of the purposes.


title: Asteroid

text: Asteroids are the leftover rock and other material from the formation of the Solar System. These rocks were too small to come together to make a planet. Some are made of carbon or metal. Depending on what's on the surface, they are classified into various asteroid spectral types including Type M (metal), Type S (stone), and Type C (carbon).


title: Asteroid

text: Most asteroids in our Solar System are in the asteroid belt between Mars and Jupiter. Many are not in the main asteroid belt. The ones that come close to Earth are called Near-Earth asteroids. Many scientists think asteroids striking the Earth killed off all the dinosaurs and caused some of the other extinction events.


title: Pashupatinath Temple

text: Pashupatinath is one of the most sacred temples of Hinduism. It is in Kathmandu, the capital city of Nepal. It is the temple of the Hindu god Shiva.


title: Steel

text: Steel is iron mixed with carbon and perhaps other metals. It is harder and stronger than iron. Iron with more than 1.7% percent carbon by weight is named cast iron. Steel is different from wrought iron, which has little or no carbon.


title: Steel

text: Steel has a long history. People in India and Sri Lanka were making small amounts of steel more than 2,500 years ago. It was very expensive and was often used to make swords and knives. In the Middle Ages, steel could be made only in small amounts since the processes took a long time.


title: Steel

text: In the time since, there have been many changes to the way steel is made. In about the year 1610 steel started to be made in England, and the way it was made got better and cheaper over the next 100 years. Cheap steel helped start the Industrial Revolution in England and in Europe. The first industrial Converter (metallurgy) for making cheap steel was the Bessemer converter, followed by Siemens-Martin open-hearth process.


title: Steel

text: Today the most common way of making steel is the basic-oxygen process. The converter is a large turnip-shaped vessel. Liquid raw iron called "pig iron" is poured in and some scrap metal is added in to balance the heat. Oxygen is then blown into the iron. The oxygen burns off the extra carbon and other impurities. Then enough carbon is added to make the carbon contents as wanted. The liquid steel is then poured. It can be either cast into molds or rolled into sheets, slabs, beams and other so-called "long products", such as railway tracks. Some special steels are made in electric arc furnaces.


title: Steel

text: Steel is most often made by machines in huge buildings called "steel mills". It is a very cheap metal and is used to make many things. Steel is used in making buildings and bridges, and all kinds of machines. Almost all ships and cars are today made from steel. When a steel object is old, or it is broken beyond repair, it is called "scrap". It can be melted down and re-shaped into a new object. Steel is "recyclable" material; that is, the same steel can be used and re-used.


title: Steel

text: Every material is made up of atoms which are very small parts. Some atoms hold together quite well, which is what makes some solid materials hard. Something made of pure iron is softer than steel because the atoms can slip over one another. If other atoms like carbon are added, they are different from iron atoms and stop the iron atoms from sliding apart so easily. This makes the metal stronger and harder.


title: Steel

text: Changing the amount of carbon (or other atoms) added to steel will change those things that are interesting and useful about the metal. These are called the properties of the steel. Some properties are:


title: Steel

text: Steel with more carbon is harder and stronger than pure iron, but it also breaks more easily (brittle).


title: Steel

text: All steels have some elements that have a bad effect, such as phosphorus (P) and sulphur (S). Steel makers take out as much P and S as possible.


title: Steel

text: Plain carbon steels are made only of iron, carbon, and undesired elements. They fall into three general groups. Plain carbon steel with 0.05 to 0.2% carbon does not harden by heat treating. Welding it is simple, so it is used for shipbuilding, boilers, pipes, fence wire and other purposes where low cost is important. Plain steels are used for springs, gears, and engine parts. Plain carbon steel with 0.45 to 0.8% carbon is used for very hard items such as shears and machine tools.


title: Steel

text: Alloy steels are plain carbon steel with metals such as Boron (B), manganese (Mn), chromium (Cr), nickel (Ni), molybdenum (Mo), tungsten (W), and cobalt (Co) added. These give other properties than plain carbon steel. Alloy steels are made for specialized purposes. For example, chromium can be added to make stainless steel, which does not rust easily, or boron can be added to make very hard steel that is also not brittle.


title: Steel

text: There are a huge number of things that people make from steel. It is one of the most common and useful metals.


title: Palaeolithic

text: The Palaeolithic (or Paleolithic) was a period of prehistory when humans made stone tools. It was the first and longest part of the Stone Age. It began around 3.3 million years ago and ended around 11,650 years ago. About 99% of human history happened in the Palaeolithic.


title: Palaeolithic

text: The Palaeolithic began when hominids (early humans) started to use stones as tools for bashing, cutting, and scraping. All members of the genus "Homo" made stone tools, starting with relatively crude tools made by "Homo habilis" and "Homo erectus". In Europe, the large-brained Neanderthal Man ("Homo neanderthalensis") made tools of high quality. Our own species, "Homo sapiens", made even higher-quality tools. These tools are the first cultural products which have survived to modern times.


title: Palaeolithic

text: The oldest stone tools ever found are about 3.3 million years old. Archaeologists found these tools in the Great Rift Valley of Africa. Australopithecines probably made them. Archaeologists have found stone tools in continental Europe from about one million years ago, and in Britain from about 700,000 years ago.


title: Palaeolithic

text: During the Palaeolithic Age, humans grouped together in small bands. They lived by gathering plants and hunting wild animals. They made tools out of wood and bone as well as stone. They probably also used leather and vegetable fibers, but these do not last as long as stone and have not survived to modern times.


title: Palaeolithic

text: The Palaeolithic ended around 11,650 years ago, when humans began to make smaller, finer tools. In Western Europe, this was the beginning of the Mesolithic period. In warmer climates like Africa, the Epipaleolithic period came after the Palaeolithic.


title: Palaeolithic

text: The Pleistocene geological epoch (also called the Ice Age) happened at the same time as the Palaeolithic. In some areas, like Western Europe, this ice age affected the way people lived. In the Middle East, people began to switch from hunting and gathering to agriculture. Both the Palaeolithic and the Pliestocene ended around the same time.


title: Palaeolithic

text: Hominids began to make Oldowan tools around 2.6 million years ago. They continued to make these tools until about 1.7 million years ago. After that, hominids began to make more sophisticated tools, which archaeologists call Acheulean.


title: Palaeolithic

text: Oldowan tools are named after Olduvai Gorge in Tanzania, where Oldowan tools were first found. The archaeologist Louis Leakey made this discovery in the 1930s. For a long time after that, archaeologists thought that the Oldowan were the earliest tools ever made. Now they know that hominids made stone tools much earlier in history - about 3.3 million years ago. This was before the genus "Homo" had evolved.


title: Palaeolithic

text: Archaeologists do not know for sure which species actually created and used Oldowan tools. The use of these tools reached its peak with early species of "Homo," such as "H. habilis" and "H. ergaster". Archaeologists think that early "Homo erectus" inherited Oldowan technology, then refined it into the Acheulean industry beginning about 1.7 million years ago. Oldowan tools are sometimes called "pebble tools", because the blanks chosen for their production already resemble, in pebble form, the final product. They are sometimes subdivided into types, such as choppers, scrapers and pounders, based on their main uses.


title: Palaeolithic

text: Around 1.7 million years ago, "Homo habilis" began to make oval- and pear-shaped hand axes. Archaeologists call these tools Acheulean. They were more sophisticated than Oldowan tools, and had more uses. Early humans made these tools in Africa, western Asia, and Europe during the Lower Palaeolithic era. They are usually found with "Homo erectus" remains.


title: Palaeolithic

text: Acheulean tools were the dominant technology for most of human history. More than a million years ago, Acheulean tool users left Africa to colonize Eurasia. Although it developed in Africa, the Acheulean industry is named after the type site of Saint-Acheul, where archaeologists first found Acheulean tools in the 19th century. This area is now a suburb of Amiens in northern France.


title: Palaeolithic

text: John Frere was the first to suggest in writing that hominids started making Acheulean tools during "a very ancient period." In 1797, Frere sent two examples of Acheulean tools to the Royal Academy in London from Hoxne in Suffolk. He had found them in prehistoric lake deposits, along with the bones of extinct animals. He concluded that they were made by people ""who had not the use of metals"" and said they belonged to a ""very ancient period indeed, even beyond the present world"". However, other archaeologist still held a pre-Darwinian view of human evolution, and they ignored Frere's ideas.


title: Palaeolithic

text: Based on radiometric dating (often potassium-argon dating), hominids began to use Acheulean techniques around 1.65 million years ago, and continued to use these tools until about 100,000 years ago. Archaeologists found the oldest known Acheulean tools in the West Turkana region of Kenya. These tools are 1.65 million years old. Some archaeologists think that hominids began to use Acheulean techniques earlier, around 1.8 million years ago.


title: Palaeolithic

text: In individual regions, scientists can use radiometric dating to determine the age of a tool much more precisely. For example, Acheulean methods did not reach Europe until around 400,000 years ago. In smaller study areas, scientists can narrow down a tool's age even more. However, numerical dates can be misleading. It is common to associate examples of this early human tool industry with one or more glacial or interglacial periods, or with a particular species of early human. The earliest user of Acheulean tools was "Homo ergaster," who first appeared about 1.8 million years ago. Some researchers prefer to call these hominids "early Homo erectus". Later forms of early humans also used Acheulean techniques. These are described below.


title: Palaeolithic

text: There is considerable time overlap in early prehistoric stone-working industries. In some regions, Acheulean tool-using groups were contemporary with other, less sophisticated industries such as the Clactonian. Then, later, Acheulean tools occur at the same time as the more sophisticated Mousterian. The Acheulean was not a neatly defined period, but a tool-making technique which flourished especially well in early prehistory. It was a basic method for making stone tools which was shared across much of the Old World.


title: Palaeolithic

text: In Europe, early humans began to make flint tools during the early part of the interglacial period, around 400,000 years ago. Archaeologists call these Clactonian tools. "Homo erectus" made Clactonian tools; modern humans did not. Early, crude flint tools from other regions, made using similar methods, are either called Clactonian tools or "core & flake" technology.


title: Palaeolithic

text: These tools are named after Clacton-on-Sea in the English county of Essex. There, in 1911, archaeologists found Clactonian artifacts along with the remains of a giant elephant and hippopotamus. These artifacts included flint chopping tools, flint flakes, and the tip of a worked wooden shaft. Archaeologists have found other Clactonian tools at sites in Swanscombe, Kent, and Barnham in Suffolk. Evidence shows that early humans made this type of tool throughout Northern Europe.


title: Palaeolithic

text: To make Clactonian tools, early humans struck thick, irregular flakes from a core of flint. They used the flint core as a chopper, and used the flakes as crude knives or scrapers. Archaeologists have found Clactonian tools which were notched, implying that they were attached to a handle or shaft.


title: Palaeolithic

text: The Clactonian and Acheulean industries might have existed at the same time. However, in 2004, archaeologists excavated a butchered Pleistocene elephant near Dartford, Kent. They found many Clactonian flint tools, but no hand axes. Since hand axes would have been more useful than choppers to dismember an elephant carcass, this is evidence that the Clactonian was a separate industry. Flint of sufficient quality was available in the area, so archaeologists think the people who carved up the elephant did not know how to make hand axes.


title: Palaeolithic

text: The Mousterian is an industry of stone tools associated with Neanderthal Man ("Homo neanderthalensis"). Early humans started making these tools around 300,000 years ago, and continued to make them until about 30,000 years ago. There are up to thirty types of Mousterian tools, compared to about six in the Acheulean style.


title: Palaeolithic

text: The Mousterian was named after the type site of Le Moustier, a rock shelter in the Dordogne region of France. Archaeologists have found similar flintwork all over unglaciated Europe, as well as the Near East and North Africa. Mousterian hand axes usually had long blades and points. Overall, these tools are finished more perfectly than any previous style of toolmaking.


title: Palaeolithic

text: To make Mousterian tools, early humans used the Levallois technique. This is a prepared-core technique: the toolmaker works on the core of the stone for so that they can strike off a long, fine blade. For this quality of work, early humans had to use a 'soft' hammer made of something like deer antler, not a stone hammer. Neanderthals had larger brains than humans; this may have helped them develop Mousterian technology.


title: Palaeolithic

text: All cultures of modern humans, "Homo sapiens", used the Mousterian style"." It is characteristic of our species to produce many more tools, all specialised for particular tasks. There are at least 100 types of tools in the Upper Palaeolithic, compared to a maximum of 30 tools in the Mousterian.


title: Palaeolithic

text: The Palaeolithic is sometimes divided into three (somewhat overlapping) periods which mark technological and cultural advances in different human communities:


title: Palaeolithic

text: The Mesolithic and Neolithic eras followed the Palaeolithic. The Neolithic ended around 1900 BC. At this time, the Stone Age ended and the Bronze Age began. Later, when the Bronze Age ended, the Iron Age began.


title: Palaeolithic

text: Venus figurines may be some of the first pieces of art ever made. These are very small statues of women, mostly pregnant with visible breasts. Archaeologists have found them in areas of Western Europe, stretching to Siberia.


title: Palaeolithic

text: Most of the Venus figurines that archaeologists have found are between 20,000 and 30,000 years old. However, they have found two figurines that are much older. The Venus of Tan-Tan, found in Morocco, is 300,000 to 500,000 years old. The Venus of Berekhat Ram, found on the Golan Heights, is between 200,000 and 300,000 years ago. These may be the some of the earliest things that show the human form.


title: Palaeolithic

text: Early humans used different kinds of stone, bones, and ivory to make these figurines. They also made Venus figurines out of clay, then hardened the clay by heating it in a fire. This is one of the earliest known uses of ceramics.


title: Palaeolithic

text: Archaeologists do not know what these figurines meant to the people who made them. There are two basic theories:


title: Palaeolithic

text: Scientists know that these figurines were not linked to the fertility of fields, because agriculture had not been discovered when the figurines were made.


title: Palaeolithic

text: The two older Venus figurines may have formed mostly through natural processes. The Venus of Tan-Tan was covered with a substance that could have been some kind of paint. The substance contained traces of iron and manganese. The figurine of Berekhat Ram has traces of tool marks. A study done in 1997 states that nature alone could not have left these traces.


title: Palaeolithic

text: Cave paintings have been found in about 350 caves in Europe. Many were done in the Palaeolothic Age, between about 15,000 and 30,000 years ago. Some of the most famous are in the Cave of Altamira in Spain and the Lascaux Cave in France. Usually, cave paintings show animals, like aurochs, bisons or horses.


title: Palaeolithic

text: Nobody knows why these paintings were done. However, archaeologists know that people did not create cave paintings just to decorate their living spaces. Usually, there are no signs that humans ever lived in the caves where people painted.


title: Palaeolithic

text: The oldest known cave paintings are in the Chauvet Cave in France. There are two groups of paintings in this cave. The first group was painted 33,000 to 30,000 years ago. The second group was done 26,000 to 27,000 years ago. We know this because scientists did radiocarbon dating of "black from drawings, from torch marks and from the floors". By 1999, scientists had dated 31 samples from the cave. The oldest were from 33,390-32,410 years ago.


title: Palaeolithic

text: Some archaeologists say this timeline is incorrect. Christian Züchner studied the style of the Chauvet paintings and compared it to paintings done at other caves. He thought one group of paintings was done between 28,000 and 23,000 years ago. He said the other group was between 18,000 and 10,000 years old. Pettitt and Bahn also think the Chauvet painting styles do not match the dates identified through radiocarbon dating.


title: Palaeolithic

text: People from the Palaeolithic era drew well. They knew about perspective, and they knew of different ways to draw. They were able to observe the behaviour of animals they painted. Some of the paintings show how the animals behaved. The paintings may have been important for rituals.


title: Palaeolithic

text: Paleolithic hunter-gatherers ate leafy vegetables, fruit, nuts, insects, meat, shellfish, and other types of fish. Because there is little direct evidence, it is almost impossible to determine how much of their diet was plant food and how much was meat. Even the idea that most humans of a given period shared the same diet is problematic. The Paleolithic was an extended period of time. During that time, there were many technological advances, many of which had impact on human dietary structure. For example, until the Middle Palaeolithic, humans probably did not have control of fire, or the tools needed to do extensive fishing. On the other hand, archaeologists generally agree that both of these technologies were widely available to humans by the end of the Paleolithic. (This allowed humans in some regions of the planet to rely heavily on fishing and hunting.)


title: Palaeolithic

text: In addition, in the Palaeolithic, human populations spread across a wide geographical area. Archaeologists think that during the Lower Paleolithic, ancestors of modern humans lived only in Africa east of the Great Rift Valley. During the Middle and Upper Paleolithic, humans greatly expanded their area of settlement, reaching ecosystems as diverse as New Guinea and Alaska. The needed to adapt their diets to the local resources that were available.


title: Palaeolithic

text: Anthropologists have different opinions about the proportions of plant and animal foods consumed. Just as with still existing hunters and gatherers, there were many varied "diets" - in different groups -of fruit and vegetables. The relative proportions of plant and animal foods in the diets of Paleolithic people often varied between regions; in colder regions, more meat was necessary. These regions were not populated by anatomically modern humans until 30,000-50,000 BP. It is generally agreed that many modern hunting and fishing tools, such as fish hooks, nets, bows, and poisons, were not introduced until the Upper Palaeolithic and possibly even Neolithic. The only hunting tools widely available to humans during any significant part of the Paleolithic period were hand-held spears and harpoons. There's evidence of Paleolithic people killing and eating seals and elands as far as 100,000 years BP. On the other hand, buffalo bones found in African caves from the same period are typically of very young or very old individuals, and there's no evidence that pigs, elephants or rhinos were hunted by humans at the time.


title: Palaeolithic

text: Another view is that until the Upper Paleolithic, humans were frugivores (fruit eaters) who supplemented their meals with carrion, eggs, and small prey such as baby birds and mussels. Only on rare occasions did they manage to kill and consume big game such as antelopes. This view is supported by studies of higher apes, particularly chimpanzees. Chimpanzees are the closest to humans genetically. They share more than 96% of their DNA code with humans, and their digestive tract is functionally very similar. Chimpanzees are primarily frugivores, but they could and would consume and digest animal flesh, given the opportunity. In general, their actual diet in the wild is about 95% plant-based, with the remaining 5% filled with insects, eggs, and baby animals. In some ecosystems, however, chimpanzees are predatory, forming parties to hunt monkeys. Some comparative studies of human and higher primate digestive tracts do suggest that humans have evolved to obtain greater amounts of calories from sources such as animal foods, allowing them to shrink the size of the gastrointestinal tract relative to body mass and to increase the brain mass instead.


title: Palaeolithic

text: Paleolithic peoples suffered less famine and malnutrition than the Neolithic farming tribes that followed them. This was partly because Paleolithic hunter-gatherers accessed to a wider variety natural foods, which allowed them a more nutritious diet and a decreased risk of famine. Many of the famines experienced by Neolithic (and some modern) farmers were caused or amplified by their dependence on a small number of crops. It is thought that wild foods can have a significantly different nutritional profile than cultivated foods. The greater amount of meat obtained by hunting big game animals in Paleolithic diets than Neolithic diets may have also allowed Paleolithic hunter-gatherers to enjoy a more nutritious diet than Neolithic agriculturalists. It has been argued that the shift from hunting and gathering to agriculture resulted in an increasing focus on a limited variety of foods, with meat likely taking a back seat to plants. It is also unlikely that Paleolithic hunter-gatherers were affected by modern diseases of affluence such as Type 2 diabetes, coronary heart disease and cerebrovascular disease, because they ate mostly lean meats and plants and frequently engaged in intense physical activity, and because the average lifespan was shorter than the age of common-onset of these conditions.


title: Palaeolithic

text: Large-seeded legumes were part of the human diet long before the Neolithic agricultural revolution, as evident from archaeobotanical finds from the Mousterian layers of Kebara Cave, in Israel.<ref name="doi10.1016/j.jas.2004.11.006"></ref> There is evidence suggesting that Paleolithic societies were gathering wild cereals for food use at least as early as 30,000 years ago. However, seeds, such as grains and beans, were rarely eaten and never in large quantities on a daily basis.<ref name="doi:10.1080/11026480510032043"></ref> Recent archeological evidence also indicates that winemaking may have originated in the Paleolithic, when early humans drank the juice of naturally fermented wild grapes from animal-skin pouches. Paleolithic humans consumed animal organ meats, including the livers, kidneys and brains. Upper Paleolithic cultures appear to have had significant knowledge about plants and herbs and may have, albeit very rarely, practiced rudimentary forms of horticulture. In particular, bananas and tubers may have been cultivated as early as 25,000 BP in southeast Asia. Late Upper Paleolithic societies also appear to have occasionally practiced pastoralism and animal husbandry, presumably for dietary reasons. For instance, some European late Upper Paleolithic cultures domesticated and raised reindeer, presumably for their meat or milk, as early as 14,000 BP. Humans also probably consumed hallucinogenic plants during the Paleolithic period. The Australian Aborigines have been consuming a variety of native animal and plant foods, called bushfood, for an estimated 60,000 years, since the Middle Paleolithic.


title: Palaeolithic

text: People during the Middle Paleolithic, such as the Neanderthals and Middle Paleolithic Homo sapiens in Africa, began to catch shellfish for food as revealed by shellfish cooking in Neanderthal sites in Italy about 110,000 years ago and Middle Paleolithic "Homo sapiens" sites at Pinnacle Point, in Africa around 164,000 BP.<ref name="NYTIMES/10/08/07"></ref> Although fishing only became common during the Upper Paleolithic, fish have been part of human diets long before the dawn of the Upper Paleolithic and have certainly been consumed by humans since at least the Middle Paleolithic. For example, the Middle Paleolithic "Homo sapiens" in the region now occupied by the Democratic Republic of the Congo hunted large -long catfish with specialized barbed fishing points as early as 90,000 years ago. The invention of fishing allowed some Upper Paleolithic and later hunter-gatherer societies to become sedentary or semi-nomadic, which altered their social structures. Example societies are the Lepenski Vir as well as some contemporary hunter-gatherers such as the Tlingit. In some instances (at least the Tlingit) they developed social stratification, slavery and complex social structures such as chiefdoms.


title: Palaeolithic

text: Anthropologists such as Tim White suggest that cannibalism was common in human societies prior to the beginning of the Upper Paleolithic, based on the large amount of “butchered human" bones found in Neanderthal and other Lower/Middle Paleolithic sites. Cannibalism in the Lower and Middle Paleolithic may have occurred because of food shortages. However, it may have been for religious reasons, and would coincide with the development of religious practices thought to have occurred during the Upper Paleolithic. Nonetheless, it remains possible that Paleolithic societies never practiced cannibalism, and that the damage to recovered human bones was either the result of ritual post-mortem bone cleaning or predation by carnivores such as saber tooth cats, lions and hyenas.


title: Donkey punch

text: The donkey punch is an act during sexual intercourse. Some people wrongly think that if a man putting his penis in his partner's vagina or anus punches the back of their neck, the vagina and anus will become very tight, giving more pleasure to the man. In fact, no such reflex exists.


title: Portugal national football team

text: Portugal national football team is the national football team of Portugal. In July 2016, they won the European Championship. Their captain is Cristiano Ronaldo.


title: Districts of Bangladesh

text: There are 64 Districts of Bangladesh known as zilas (Bengali: জেলা "jela" - district). The districts are further subdivided into 493 sub-districts, or upazila (উপজেলা "upojela").


title: Districts of Bangladesh

text: These 64 districts make up the eight divisions of Bangladesh, the districts are listed below in alphabetical order by division. The official English name of each district is followed by the official Bengali name (in brackets).


title: Atlantic Ocean

text: The Atlantic Ocean is the world's second largest ocean. It covers a total area of about . It covers about 20 percent of the Earth's surface. It is named after the god Atlas from Greek mythology.


title: Atlantic Ocean

text: The Atlantic formed when the Americas moved west from Eurasia and Africa. This began sometime in the Cretaceous period, roughly 135 million years ago. It was part of the break-up of the supercontinent Pangaea.


title: Atlantic Ocean

text: The east coast of South America is shaped somewhat like the west coast of Africa, and this gave a clue that continents moved over long periods of time (continental drift). The Atlantic Ocean is still growing now, because of sea-floor spreading from the mid-Atlantic Ridge, while the Pacific Ocean is said to be shrinking because the sea floor is folding under itself or subducting into the mantle.


title: Atlantic Ocean

text: The Atlantic Ocean is bounded on the west by North and South America. It connects to the Arctic Ocean through the Denmark Strait, Greenland Sea, Norwegian Sea and Barents Sea. It connects with the Mediterranean Sea through the Strait of Gibraltar.


title: Atlantic Ocean

text: In the southeast, the Atlantic merges into the Indian Ocean. The 20° East meridian defines its border.


title: Atlantic Ocean

text: In the southwest, the Drake Passage connects it to the Pacific Ocean. The Panama Canal links the Atlantic and Pacific.


title: Atlantic Ocean

text: The Atlantic Ocean is second in size to the Pacific. It occupies an area of about . The volume of the Atlantic, along with its adjacent seas (the seas next to it), is 354,700,000 cubic kilometres.


title: Atlantic Ocean

text: The average depth of the Atlantic, along with its adjacent seas, is . The greatest depth is Milwaukee Deep near Puerto Rico, where the Ocean is deep.


title: Atlantic Ocean

text: The Atlantic Ocean has important ocean currents. One of these, called the Gulf Stream, flows across the North Atlantic. Water gets heated by the sun in the Caribbean Sea and then moves northwest toward the North Pole. This makes France, the British Isles, Iceland, and Norway in Europe much warmer in winter than Newfoundland and Nova Scotia in Canada. Without the Gulf Stream, the climates of northeast Canada and northwest Europe might be the same, because these places are about the same distance from the North Pole.


title: Atlantic Ocean

text: There are currents in the South Atlantic too, but the shape of this sea means that it has less effect on South Africa.


title: Atlantic Ocean

text: The main feature of the Atlantic Ocean's seabed is a large underwater mountain chain called the Mid-Atlantic Ridge. It runs from north to south under the Ocean. This is at the boundary of four tectonic plates: Eurasian, North American, South American and African. The ridge extends from Iceland in the north to about 58° south.


title: Atlantic Ocean

text: The salinity of the surface waters of the open ocean ranges from 3337 parts per thousand and varies with latitude and season.


title: Website

text: A website is a set of webpages that are joined. People look at websites with a computer of some kind, sometimes including the computer inside mobile phones and televisions. The websites are kept on computers called web servers.


title: Website

text: There is almost always a single homepage which has links to other pages that are part of that "site". Sometimes it has links to pages that are part of other "sites" as well. (Note that net jargon uses the word site, which also means a physical place in the real world, to mean a web URL). A home page serves as the introduction page of a website.


title: Website

text: Websites can be used to advertise or sell things. They can also be used to talk to other people. A blog is a website where the location of the material is less relevant than who writes it, and which is more focused on dialogue. Very often the people who use blogs dislike the word "site" since it implies a controlled place. Sites are good for looking up information on the computer.


title: Website

text: There are many different types of website based on their purpose and the type of organisation they are created for.


title: Website

text: Users can access any website by using a URL. This is the website address which is shown near the top of the web browser. The homepage and the rest of the site usually have the same words at the start of the URL — for example, pages at the Simple English Wikipedia always start "http://simple.wikipedia.org/..." but are different after that. However, if a person does not buy a domain name, the website could be an IP Address. An example of an IP address is 172.217.13.228.


title: Website

text: Web sites are usually shown in HTML (Hyper Text Markup Language) but are not always written or kept that way - some use WAP and others use XML.


title: Website

text: Website builder software is usually a collection of software tools that allow the construction of websites without manual code editing. Several hosted website services have website builder software built-in.


title: North Korea

text: North Korea (officially called the Democratic People's Republic of Korea (DPRK)), is a country in the northern part of the Korean peninsula. North Korea is next to China, Russia, and South Korea. The capital city of North Korea is Pyŏngyang, which is also the largest city.


title: North Korea

text: The country was founded in 1948 after it had been freed from Japanese occupation, and a socialist state backed by the Soviet Union was established. The Republic of Korea is the southern half of the Korean Peninsula, and was occupied by the United States, and the U.S. set up a democracy in the south. At first, there was a war between the north and south which is called the Korean War, but while the fighting stopped in 1953, the war never officially ended. North Korea had ties with China and Russia but never was formally allied with either and became more isolated over time. Soon afterwards, the North's main trading partners the Soviet Union, collapsed. This left North Korea stranded and isolated. Throughout the 1990s, North Korea suffered from famines and natural disasters. As South Korea got richer, North Korea got poorer and life became worse there. Afterwards, things stabilized but continued to lag behind the South. Worldwide economic sanctions and embargoes are thought to have significantly impacted the quality of life in North Korea.


title: North Korea

text: North Korea is described as a totalitarian Stalinist dictatorship by western media, while North Korea describes itself as a democratic worker's state. The country's leader Kim Il-sung said that the government was following his own ideology of "Juche", which means "self-reliance". Later on, the country's leaders began to remove "communism" from North Korean laws and philosophy, although Juche can be described as a variant of communism. After Kim Il-sung died during the disasters of the 1990s, his son Kim Jong-il took his place and was promoted by the government as the leader who led North Korea out of the disasters. North Korea was the only communist country in history where leadership was directly given to the former leader's son after his death. This is called hereditary rule. Kim Jong-il enacted a new policy of "Songun", or "military-first", which turned the country into a military state. When he died in 2011, his youngest son Kim Jong-un took his place and continues to lead the country today.


title: North Korea

text: Historians believe that the Korean people have lived in the area for thousands of years. Before 1910, Korea was one country. It had a king and people were mostly farmers. The country was peaceful and was not communist. In 1910, that changed. Japan and Russia went to war. Since Japan and Russia were both very close to Korea, Japan took Korea for themselves as part of Japan. Japan then had control.


title: North Korea

text: Between 1910 and the end of World War II in 1945, Korea was considered a part of Japan due to Japan's colonization of Korea. In 1945, the USSR declared war on Japan and the United States bombed it (Nagasaki and Hiroshima); severely weakening its empire and forcing Japan to surrender. Japan's weak status allowed the Soviets to enter Korea fairly, freely and occupy the northern half whilst the United States took the southern half. Each created governments supporting their own ideologies, Marxist–Leninist Single Party State (North) and Democratic Capitalist State (South).


title: North Korea

text: In 1950, North Korea sent soldiers to South Korea. North Korea wanted to bring together North and South Korea to form a single Korean country, and Korean families that had been split by the division of North and South to be together again. The North Korean leaders wanted South Korea to be communist, like North Korea and the Soviet Union were.


title: North Korea

text: The United Nations sent soldiers to Korea. These soldiers came from many countries. These countries did not like Communism (to learn more, see the article about the Cold War). If South Korea became Communist, then maybe other countries would too. General Douglas MacArthur led the soldiers.


title: North Korea

text: North Korea had taken over much of South Korea by force. With the help of the other countries, South Korea took back their land, and even much of North Korea, up to the Yalu River, which forms the border between North Korea and China. China, which was also communist, helped the North Koreans to get the land back that the South Korean soldiers had taken.


title: North Korea

text: After three years, in 1953, North Korea and South Korea both decided that no one would win the war and both countries signed an armistice, which is an agreement that made both countries stop fighting. North Korea and South Korea were divided by a demilitarized zone, or DMZ, which is a special place that surrounds the border between North and South Korea where both countries can not place lots of soldiers, so that fighting does not start again.


title: North Korea

text: Even though the Korean Demilitarized Zone is meant to stop problems between the two countries, sometimes soldiers on both sides of the border fire their guns at each other. A special town in the zone, Panmunjom, is called the Joint Security Area, or JSA, and sometimes the leaders of both countries meet there to talk about possibly coming back together.


title: North Korea

text: North Korea is one of the few countries in the world that has made nuclear missiles, which can kill many people if they are exploded. North Korea will not say how many nukes it has, but other countries think that the North Korean government probably has built ten missiles so far out of a deadly element called plutonium.


title: North Korea

text: In October 2006, North Korea said that it tested one of its nuclear bombs. Although the North Korean government said that the test was not dangerous, many other countries and the United Nations were nonetheless enraged.


title: North Korea

text: Three years later in 2009, North Korea did another test, which broke a United Nations law called Resolution 1718, which said North Korea could not keep building and testing nuclear bombs.


title: North Korea

text: In 2010, a South Korean warship sank, killing over 40 soldiers. An international investigation concluded that North Korea had sunk a South Korean warship with a torpedo. North Korea strongly said that it did not have anything to do with the sinking. When the United States and South Korea planned to set up defenses in case North Korea tried to attack again, North Korea's National Defense Commission threatened on to start a war with its nuclear weapons.


title: North Korea

text: In April 2012, North Korea launched a rocket called Bright Star 3. The reasons for the launch were science and the 100th anniversary of the birth of the country's founder, Kim Il-Sung.


title: North Korea

text: The government said the rocket carried a weather satellite so the government could find out what the weather would be. However, other countries said that the weather satellite was a story made up by the government so the real purpose of the rocket would not the known—which most countries thought was to test a nuclear missile that could be launched at the United States or South Korea. South Korean leaders said it would shoot the rocket down when it came over South Korea.


title: North Korea

text: Because of this rocket, other countries stopped helping North Korea, even though the government invited other countries to see the rocket launch to make it seem like the North Koreans had nothing to hide from other countries. The rocket was eventually launched, but it did not work and crashed just a minute and thirty seconds after it was launched. In December 2012, the government tried to launch the rocket again. It worked this time and went into orbit circling the Earth, though the United States said that it was very unstable and might fall back to Earth. Experts in Europe noticed the satellite's reflection was fluctuating (getting brighter then dimmer); indicating that the satellite is tumbling in its orbit.


title: North Korea

text: In February 2013, North Korea tested a nuclear bomb for the 3rd time, causing much outrage from other countries. The government also released many videos that depicted possible missile targets in the United States. North Korea however does not posses missiles that could reach US mainland but some say Hawaii is a possibility. It is highly unlikely that North Korea would ever fire against the US, Japan or South Korea. Many missiles depicted in DPRK parades are fakes used to exaggerate North Korea's military strength. Most of its inventory dates from the Soviet years.


title: North Korea

text: People often think that North Korea is a communist country. It is actually a socialist-military dictatorship. In its most recent constitutional change, the word 'communism' was removed. Large pictures of Karl Marx and Vladimir Lenin were removed from Kim Il-Sung square in 2012. The government has a similar structure to the former Soviet Union (USSR), once a close ally, but it is very different from the USSR. Leaders of the USSR were elected by a group of government officials. In North Korea, the new leader is the current leader's male heir. For this reason, North Korea is often referred to as a hereditary dictatorship.


title: North Korea

text: North Korea's official state ideology is Juche. That is a form of socialism developed by the country's founder, Kim Il-Sung. Juche means self-reliance. It teaches that to achieve true socialism and become self-sufficient, the state must become fully isolated from the rest of society.


title: North Korea

text: In July 1994, Kim died. His son, Kim Jŏng-Il, took over. He became the third supreme leader and party general secretary.


title: North Korea

text: "Songun" is a North Korean idea. It means "army first." The job of every North Korean person is to feed the Army. Kim Jŏng-Un is the "General Secretary of the Workers' Party of Korea". That is one of many jobs he has. He is like a king, and can do what he wants. The average North Korean citizen makes around $900 a year. Kim Jŏng-Un makes around $800,000 a year. He lives in a palace. He has lots of soldiers who go wherever he goes to protect him.


title: North Korea

text: North Korea is technically a multi-party state since other parties do exist besides the Korean Workers' Party (KWP). However, the KWP also controls the other parties so it can stay in power. The constitution claims that North Korea's citizens have freedom of speech, religion and press. In real life, these citizens do not have these rights. People can be jailed if they criticise the party, government, or leaders. North Koreans are encouraged to report family members to the police if they think they are doing something illegal. In return they get more privileges. If someone is caught doing a crime, their whole family will be sent along with them to a labour camp. Most die there, but a few escape.


title: North Korea

text: North Korean people have very little freedom of speech. They get their news from the Korean Central News Agency (KCNA). The KCNA makes sure all the country's television, radio, and newspaper news makes the government look good. This is called propaganda. The government blocks access to the Internet. Only a few trusted military officials and party members can access the world Internet. It has been reported that almost all North Koreans do not know that men have landed on the moon. The government runs an intranet service that is available on all North Korean computers. It is nothing like the real Internet but is filled with propaganda that makes the government, party, and leaders look good. The government also tries to keep ideas from other countries out of North Korea.


title: North Korea

text: Capital punishment is a common type of punishment in North Korea. Stealing, murder, rape, drug smuggling, attempted murder, spying, slaughtering cattle for food, trying to challenge the laws of North Korea, traveling without permission, looking at media unapproved by North Korea (which includes South Korean dramas, pornography, and Western movies), possessing a USB drive, and practicing religions that are against worshipping Kim Jong-un and his family can all result in the death penalty.


title: North Korea

text: In parts of the country, there is not enough food. Currently, other countries give food to some people in North Korea. This is called "foreign aid". The aid sometimes stops coming if North Korea is thought to be testing nuclear bombs. Very recently, North Korea's food aid stopped after the government launched a satellite in April 2012. Other countries said North Korea had broken their side of an agreement. The North Korean government said that it was the United States that had broken the agreement.


title: North Korea

text: It is hard for people from other countries to visit North Korea. Visitors must be guided by two army members called "minders". The minders try and make sure the people do not find out about anything that might make the government look bad.


title: North Korea

text: North Korea is one of the poorest countries in the world. This is due to the government not wanting to allow North Koreans to earn their own money outside of their government-given jobs, to allow people to work the jobs they want, and to trade with other countries.


title: North Korea

text: Although Pyongyang (which is the one of the few areas foreign travelers are allowed to visit) makes the country look like it is richer and more prosperous than it truly is, life looks extremely different throughout the rest of the country. Only the highest-ranking North Koreans are allowed to live in Pyongyang, and they must have permission from the government to do so. Unlike the rest of the country, people often own cars and bicycles, there is a subway system, and power exists throughout the city. Meanwhile, very few people in the countryside own a car, or even a bicycle, and animal-drawn carts are very common. Electricity in rural areas is rare, if it even exists at all. Proof of this is that when seen from space, there are almost no lights that can be seen outside of Pyongyang. Even in Pyongyang, power cuts are common.


title: North Korea

text: As said earlier, starvation is very common way to die throughout the country. The soil in most of the country is not good enough to grow enough crops to feed people without any kind of fertilizer. As a result, people often steal human poop to fertilize the soil. People also go out into nature to look for anything to eat such as grass, bark, frogs, worms, etc.


title: North Korea

text: Since the government does not provide the average North Korean person enough resources to survive, most North Koreans get what they need from the black market. Even though buying and selling on the black market is illegal, people are able to avoid punishment by bribing officials. They might give things such as money, gifts, or sexual favors. Most people buying and selling at the black market are women. This is because all adult men are required by law to go to work during workhours, even when their workplace cannot or will not pay them for their work.


title: North Korea

text: Since electricity is rare throughout North Korea, tasks such as cooking and washing clothes take much longer and are more tiring. People often wash clothes in a river or creek and must start fires before they can cook.


title: North Korea

text: Although healthcare is free in North Korea, most hospitals and doctor's offices do not have the medicines or supplies needed to correctly treat patients. As a result, many patients die or become crippled for the rest of their lives in the hospital. On one occasion, North Korea hired an eye surgeon from Nepal to because there was not a single eye surgeon in the country.


title: North Korea

text: In order to raise money for the country, the government sometimes sends North Korean citizens to its allies, like China and Russia, to do work there. These jobs include food service in North Korean restaurants and logging. Even outside of North Korea, these North Koreans are often not allowed to interact with the local people outside of work, are forced to live in North Korean communities, and must obey North Korean laws.


title: North Korea

text: Other ways North Korea makes money is through selling illegal drugs to other countries, making fake money of other countries, and stealing money online.


title: North Korea

text: Historically, both South Korea and North Korea have the same set of values. In 1945, the peninsula was divided. Since then, the government of both North and South Korea were different. This has led to different developments in both North and South Korea.


title: North Korea

text: Human Rights Watch says that free religious activities do not exist in North Korea. The culture in Korea has been influenced by that of China. Despite this, Korea has developed a cultural identity that is different from that of Mainland China.


title: North Korea

text: Literature and arts in North Korea are state-controlled. Specialized committees of the KWP are responsible for this. Film is also a significant artistic medium in North Korea and Kim Jong Il's manifesto "The Cinema and Directing" (1987) is the basis for the nation's filmmakers.


title: North Korea

text: Korean culture came under attack during the Japanese rule from 1910 to 1945. Japan enforced a cultural assimilation policy. During the Japanese rule, Koreans were forced to learn and speak Japanese, adopt the Japanese family name system and Shinto religion, and were forbidden to write or speak the Korean language in schools, businesses, or public places. In addition, the Japanese altered or destroyed various Korean monuments including Gyeongbok Palace and documents which portrayed the Japanese in a negative light were revised.


title: North Korea

text: Both Koreas share a Buddhist and Confucian heritage and a recent history of Christian and Cheondoism ("religion of the Heavenly Way") movements. The North Korean constitution states that freedom of religion is permitted. According to the Western standards of religion, the majority of the North Korean population could be characterized as non-religious. However, the cultural influence of such traditional religions as Buddhism and Confucianism still have an effect on North Korean spiritual life.


title: North Korea

text: It seems that Buddhists are accepted more than other religious groups. Christians are said to be severely persecuted by the authorities, often by throwing them in prison or executing them publicly. Buddhists are given limited funding by the government to promote the religion, because Buddhism played an integral role in traditional Korean culture. In May 2014, an American tourist was arrested at Pyongyang Sunan Airport after it was discovered he left a Bible in a nightclub on the DPRK's east coast. He was convicted of attempting to overthrow the government but was eventually released several months later. At the time of his imprisonment, there were two other American citizens held by North Korea awaiting transfer to political prison camps. Both have since been released.


title: North Korea

text: Even though the country only has fewer than 25 million people, the country still has the world's fourth largest standing military at 1.28 million soldiers. This is because North Korea has a law that requires all men to join the military for ten years after they graduate high school.


title: North Korea

text: The government says it keeps a large military to protect the country from its enemies, particularly the United States and Japan. However, it is more likely that it exists to keep the government in power.


title: Entertainment

text: Entertainment is something that gives pleasure, or distracts a person from daily life, like a sport or game that excites people and keeps their attention. Some entertainment, like horror movies, can also make people feel sad or scared. Other entertainment, like comedy shows, are funny.


title: Entertainment

text: Entertainments is a form of activity that holds the attention and interest of an audience, or gives pleasure and delight. it can be an idea or an activity or even a task.


title: Johannes Gutenberg

text: Johannes Gensfleisch zur Laden zum Gutenberg (more commonly known as Johannes Gutenberg) (1390s – 3 February 1468), was a German metal-worker and inventor. He is famous for his work in printing in the 1450s, and is specifically known for inventing typography.


title: Johannes Gutenberg

text: Gutenberg was born in Mainz, Germany, as the son of a merchant, Friele Gensfleisch zur Laden. Gutenberg's father took the surname "zum Gutenberg" after the name of the place they now lived.


title: Johannes Gutenberg

text: Gutenberg invented a sort of metal alloy for printing; inks; a way to fix type (metal letters) very accurately; and a new sort of printing press. He took the idea for his printing press from the presses wine-makers used. Many people say Gutenberg invented printing with moveable type, but it was already invented in China before that: see printing.


title: Johannes Gutenberg

text: Before movable type, people used block printing, where the printer prints a whole page from one piece of metal or wood. With movable type, the printer makes a letter (A, B, C ...) from a piece of metal or wood, and can use it again and again in different words. Together, all Gutenberg's inventions made printing fast. In Renaissance Europe, the improved information technology made an information explosion – in a short time, people printed many new books about many topics.


title: Johannes Gutenberg

text: The high number of new books was partly because of the popular Bible Gutenberg printed – the Gutenberg Bible. This was the first Bible people made in large numbers; Gutenberg started on 23 February 1455. Gutenberg was not a clever businessman, and did not get much money from his system. He had legal problems, and lost his machines to his partner, Johann Fust. The Archbishop at the time sympathized with Gutenberg because of his contributions to society, so told him that he would receive a pension each year with clothes, wine, and grain. Gutenberg died in Mainz, Germany, in 1468.


title: Johannes Gutenberg

text: In his lifetime Gutenberg was not successful, but his invention was very important. In a short time, news and books were traveling around Europe very fast. Scientists could communicate better, which helped bring the scientific revolution and new technology. More Europeans, not just priests, scribes and scholars, learned to read.


title: Johannes Gutenberg

text: Today, there are still 60 Gutenberg Bibles. They are probably the oldest books that printers made with moveable type.


title: Johannes Gutenberg

text: The "Gutenberg Galaxy" and Project Gutenberg use Gutenberg's name. The city of Guttenberg, Iowa in the United States is named after him.


title: Adaptation

text: Adaptation is the evolutionary process where an organism becomes better suited to its habitat. This process takes place over many generations. It is one of the basic phenomena of biology.


title: Adaptation

text: When people speak about adaptation, they often mean a 'feature' (a trait) which helps an animal or plant survive. An example is the adaptation of horses' teeth to grinding grass. Grass is their usual food; it wears the teeth down, but horses' teeth continue to grow during life. Horses also have adapted to run fast, which helps them to escape their predators, such as lions. These features are the "product" of the process of adaptation.


title: Adaptation

text: The illustration of bird beaks shows an obvious sign of their different ways of life. However, eating a different food also means having a different digestive system, gut, claws, wings and above all, different inherited behaviour. For the major adaptations, what changes is not a single trait, but a whole group of features.


title: Adaptation

text: Adaptation occurs because the better adapted animals are the most likely to survive, and to reproduce successfully. This process is known as natural selection; it is the basic cause of evolutionary change.


title: Adaptation

text: Adaptation... could no longer be considered a static condition, a product of a creative past, and became instead a continuing dynamic process. "Ernst Mayr".


title: Adaptation

text: An internal parasite (such as a fluke) is a good example: it has a very simple bodily structure, but still the organism is highly adapted to its particular environment. From this we see that adaptation is not just a matter of visible traits: in such parasites critical adaptations take place in the life cycle, which is often quite complex.


title: Adaptation

text: However, as a practical term, adaptation is often used for the "product": those features of a species which result from the process. Many aspects of an animal or plant can be correctly called adaptations, though there are always some features whose function is in doubt. By using the term "adaptation" for the evolutionary "process", and "adaptive trait" for the bodily part or function (the product), the two senses of the word may be distinguished.


title: Adaptation

text: Adaptation is one of the two main processes that explain the diverse species we see in biology. The other is speciation (species-splitting or cladogenesis). A favourite example used today to study the interplay of adaptation and speciation is the evolution of cichlid fish in African lakes.


title: Adaptation

text: An organism must be viable at all stages of its development and at all stages of its evolution. This places "constraints" on the evolution of development, behaviour and structure of organisms.


title: Adaptation

text: The general idea is that each genetic and phenotypic change during evolution should be relatively small, because developmental systems are so complex and interlinked. But polyploidy in plants is a fairly common large genetic change. The origin of the eukaryota by the symbiosis of micro-organisms is a more exotic example.


title: Adaptation

text: All adaptations help organisms survive in their ecological niches. This implies an increase in biological fitness.


title: Adaptation

text: These adaptive traits may be structural, behavioural or physiological. Structural adaptations are physical features of an organism (shape, body covering, armament; and also the internal organization).


title: Adaptation

text: Behavioural adaptations are composed of inherited behaviour chains and/or the ability to learn: behaviours may be inherited in detail (instincts), or a tendency for learning may be inherited (see neuropsychology). Examples: searching for food, sex, vocalizations.


title: Adaptation

text: Physiological adaptations permit the organism to perform special functions (for instance, making venom, secreting slime, phototropism); but also more general functions such as growth and development, temperature regulation, ionic balance and other aspects of homeostasis. Adaptation, then, affects all aspects of the life of an organism.


title: Adaptation

text: Important adaptations do not come singly. They come in groups, which work together to make the animal or plant successful in its particular niche or life-style.


title: Adaptation

text: Woodpecker adaptations are a good example of how a whole suite of features are needed for a successful way of life.


title: Adaptation

text: Ancestral woodpeckers, which switched to climbing on tree trunks, had ancestral foot and tail structure. This suggests that a change in behaviour, perhaps to get at a better food source, was one of the first things that happened in the chain of events. The way evolutionary novelties start is an important topic.


title: Adaptation

text: Not all features of an organism are adaptations. It may need field investigations or experiments to find out whether it has a function in the life of the species.


title: Adaptation

text: Adaptations tend to reflect the past life of a species. If a species has recently changed its life style, a once valuable adaptation may become a dwindling vestige. Animals which live in dark caves often lose, over a long period, their colours and eyesight.


title: Adaptation

text: The reasons for this may vary. The loss of structure and function may be a positive adaptation which saves energy and materials. But it may be simply a by-product of genes selected for other functions (pleiotropy). Or the structure may be linked in development, and affected by selection for some other structure.


title: Adaptation

text: It is a general rule that any adaptations which are no longer useful either become vestigial organs (see vermiform appendix), or may be selected and adapted to other functions (see ear ossicles).


title: Adaptation

text: Many adaptations serve more than one function. This is often the reason some traits become so noticeable that they almost define the species concerned. The legs of a horse are also a main defence: a horse's kick is very destructive. The antlers of male deer serve a sexual function as well as a defence against predators. Man's large brain serves not only for language, but also for thinking and problem-solving. Bird feathers are not just used to fly; they are the basis of its heat conservation, temperature regulation and signalling


title: Adaptation

text: It is a profound truth that Nature does not know best; that genetical evolution... is a story of waste, makeshift, compromise and blunder. "Peter Medawar".


title: Adaptation

text: Adaptations are never perfect. There are always tradeoffs between the various functions and structures in a body. It is the organism as a whole which lives and reproduces, therefore it is the complete set of adaptations which gets passed on to future generations.


title: Adaptation

text: All adaptations have a downside: horse legs are great for running on grass, but they cannot scratch their backs; mammals' hair helps temperature regulation, but offers a niche for ectoparasites. Compromise and make-shift occur widely, not perfection. Selection pressures pull in different directions, and the adaptation that results is some kind of compromise.


title: Adaptation

text: Since the phenotype as a whole is the target of selection, it is impossible to improve simultaneously all aspects of the phenotype to the same degree. "Ernst Mayr".


title: Adaptation

text: Camouflage to avoid detection is destroyed when vivid colours are displayed at mating time. Here the risk to life is counterbalanced by the need for reproduction. The peacock's ornamental train (grown anew in time for each mating season) is a famous adaptation. It must reduce his maneuverability and flight, and is hugely conspicuous; also, its growth costs food resources.


title: Adaptation

text: Darwin's explanation of its advantage was in terms of sexual selection: "it depends on the advantage which certain individuals have over other individuals of the same sex and species, in relation to reproduction". The kind of sexual selection represented by the peacock is called 'mate choice', meaning the process selects the more fit over the less fit, and so has survival value. In practice, the blue peafowl "Pavo cristatus" is a pretty successful species, with a big natural range in India, so the overall outcome of their mating system is quite viable.


title: Adaptation

text: The size of the human foetal brain at birth means the brain of a newborn child is quite immature. The newborn's brain cannot be larger than about 400ccs, else it will not get through the mother's pelvis. Yet the size needed for an adult brain is about 1400ccs.


title: Adaptation

text: The most vital things in human life (locomotion, speech) just have to wait while the brain grows and matures. That is the result of the birth compromise. Much of the problem comes from our upright bipedal stance, without which our pelvis could be shaped more suitably for birth. Neanderthals had a similar problem.


title: Adaptation

text: The function of a trait can, and often does, change over time. Several terms have been used to describe this: "preadaptation", "exaptation", "cooption". 'Preadaptation' is the most common term used when a preexisting structure or trait inherited from an ancestor evolves a different function. It was the term used by Julian Huxley and Ernst Mayr. The term 'pre-' does not mean any foresight, it just means the adaptation was already available, serving some older function. 'Exaptation' was Stephen J. Gould's word.


title: Adaptation

text: One example of preadaptation is in dinosaurs, which evolved feathers with the function of thermo-insulation and display long before they were used for flight by early birds. Sweat glands in mammals were later transformed into mammary glands. Another example is the long journey of the mammalian ear ossicles, which started in the gill covers of ancient fish, then became part of the lower jaw of reptiles, and then became part of the inner ear of mammals. Another example is the wings of penguins. Once used for flying, they are now used for 'flying' under water.


title: Adaptation

text: Change of function in organs and structures is extremely common in evolution. Many of the features of tetrapods (land vertebrates) evolved from features with different functions in the ancestral lobe-finned fish (Sarcopterygii).