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92-556: (Redirected from Twinned ) [REDACTED] Look up twinning in Wiktionary, the free dictionary. Twinning (making a twin of) may refer to: In biology and agriculture, producing two offspring (i.e., twins ) at a time, or having a tendency to do so In engineering and manufacturing, the creation of a digital twin or the synching of such twins Twinning (cooperation) Afri Twin , an exchange partnership between schools in

184-527: A 2015 reality show on VH1 See also [ edit ] Twining (disambiguation) Topics referred to by the same term [REDACTED] This disambiguation page lists articles associated with the title Twinning . If an internal link led you here, you may wish to change the link to point directly to the intended article. Retrieved from " https://en.wikipedia.org/w/index.php?title=Twinning&oldid=1243664121 " Category : Disambiguation pages Hidden categories: Short description

276-698: A fleet to reach Peru by sea, and sought the military support of various rebels from the Viceroyalty of Peru. In 1822 the two men met at the Guayaquil Conference in Ecuador, where they failed to agree on governance strategies for the liberated nations. Two years later Bolívar's forces beat the Spanish at the Battle of Ayacucho , securing the independence of Peru and the rest of South America. In

368-497: A greater chance of dizygotic multiple births. In the United States it has been estimated that by 2011 36% of twin births resulted from conception by assisted reproductive technology . The risk of twin birth can vary depending on what types of fertility treatments are used. With in vitro fertilisation (IVF), this is primarily due to the insertion of multiple embryos into the uterus. Ovarian hyperstimulation without IVF has

460-459: A long history of colonialism , the overwhelming majority of South Americans speak Spanish or Portuguese , and societies and states are rich in Western traditions . Relative to Africa, Asia, and Europe, post-1900 South America has been a peaceful continent with few wars, although high rates of violent crime remain a concern in some countries. South America occupies the southern portion of

552-506: A more likely explanation. A high twinning rate has also been observed in other places of the world, including: The widespread use of fertility drugs causing hyperovulation (stimulated release of multiple eggs by the mother) has caused what some call an "epidemic of multiple births ". In 2001, for the first time ever in the US , the twinning rate exceeded 3% of all births. Nevertheless, the rate of monozygotic twins remains at about 1 in 333 across

644-460: A pair of monozygotic twins reproduces with another pair or with the same person), rather than first cousins. Identical twins do not have the same fingerprints however, because even within the confines of the womb, the fetuses touch different parts of their environment, giving rise to small variations in their corresponding prints and thus making them unique. Monozygotic twins always have the same genotype . Normally due to an environmental factor or

736-682: A part of Oceania, also administered by Chile), the Galápagos Islands (administered by Ecuador , sometimes considered part of Oceania), and Tierra del Fuego (split between Argentina and Chile). In the Atlantic Ocean, Brazil administers Fernando de Noronha , Trindade and Martim Vaz , and the Saint Peter and Saint Paul Archipelago , while the Falkland Islands (Spanish: Islas Malvinas ) and South Georgia and

828-545: A rate of about 3 in every 1000 deliveries worldwide. The likelihood of a single fertilization resulting in monozygotic twins is uniformly distributed in all populations around the world. This is in marked contrast to dizygotic twinning, which ranges from about six per thousand births in Japan (almost similar to the rate of identical twins, which is around 4–5) to 15 and more per thousand in some parts of India and up to over 20 in some Central African countries. The exact cause for

920-406: A separate fetus, rather than by the embryo splitting while hatching from the zona pellucida (the gelatinous protective coating around the blastocyst). Monozygotic twins may also be created artificially by embryo splitting. It can be used as an expansion of in vitro fertilization (IVF) to increase the number of available embryos for embryo transfer . Monozygotic twinning occurs in birthing at

1012-481: A site called Chavín de Huantar in modern Peru at an elevation of 3,177 meters (10,423 ft). Chavín civilization spanned 900 BC to 300 BC. In the central coast of Peru, around the beginning of the 1st millennium AD, Moche (100 BC – 700 AD, at the northern coast of Peru), Paracas and Nazca (400 BC – 800 AD, Peru) cultures flourished with centralized states with permanent militia improving agriculture through irrigation and new styles of ceramic art. At

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1104-541: A study in 2012 found that it is possible for a polar body to result in a healthy fetus. In 2003, a study argued that many cases of triploidy arise from sesquizygotic (semi-identical) twinning which happens when a single egg is fertilized by two sperm and splits the three sets of chromosomes into two separate cell sets. The degree of separation of the twins in utero depends on if and when they split into two zygotes. Dizygotic twins were always two zygotes. Monozygotic twins split into two zygotes at some time very early in

1196-689: A subtropical climate of the dinaric type. At the highest points of the Andean region, climates are colder than the ones occurring at the highest point of the Norwegian fjords. In the Andean plateaus, the warm climate prevails, although it is tempered by the altitude, while in the coastal strip, there is an equatorial climate of the Guinean type. From this point until the north of the Chilean coast appear, successively, Mediterranean oceanic climate , temperate of

1288-478: A very high risk of multiple birth. Reversal of anovulation with clomifene (trade names including Clomid ) has a relatively less but yet significant risk of multiple pregnancy. A 15-year German study of 8,220 vaginally delivered twins (that is, 4,110 pregnancies) in Hesse yielded a mean delivery time interval of 13.5 minutes. The delivery interval between the twins was measured as follows: The study stated that

1380-557: Is a genetically linked tendency to hyper- ovulate . There is no known genetic link for identical twinning. Other factors that increase the odds of having fraternal twins include maternal age, fertility drugs and other fertility treatments, nutrition, and prior births. Some women intentionally turn to fertility drugs in order to conceive twins. The vast majority of twins are either dizygotic (fraternal) or monozygotic (identical). In humans dizygotic twins occur more often than monozygotic twins. Less common variants are discussed further down

1472-526: Is because the most extensive part of the continent is in the equatorial zone (the region has more areas of equatorial plains than any other region), therefore giving the Southern Cone more oceanic influence, which moderates year round temperatures. The average annual temperatures in the Amazon basin oscillate around 27 °C (81 °F), with low thermal amplitudes and high rainfall indices. Between

1564-460: Is by far the most populous South American country, with almost half of the continent's population, followed by Colombia, Argentina, Venezuela, and Peru. In recent decades, Brazil has also generated half of the continent's GDP and has become the continent's first regional power. Most of the population lives near the continent's western or eastern coasts while the interior and the far south are sparsely populated. The geography of western South America

1656-493: Is different from Wikidata All article disambiguation pages All disambiguation pages Twin In contrast, a fetus that develops alone in the womb (the much more common case in humans) is called a singleton , and the general term for one offspring of a multiple birth is a multiple . Unrelated look-alikes whose resemblance parallels that of twins are referred to as doppelgänger . The human twin birth rate in

1748-605: Is dominated by the Andes mountains; in contrast, the eastern part contains both highland regions and vast lowlands where rivers such as the Amazon , Orinoco and Paraná flow. Most of the continent lies in the tropics, except for a large part of the Southern Cone located in the middle latitudes . The continent's cultural and ethnic outlook has its origin with the interaction of Indigenous peoples with European conquerors and immigrants and, more locally, with African slaves . Given

1840-446: Is fertilized to form one zygote (hence, "monozygotic") which then divides into two separate embryos . The chances of having identical twins is relatively rare – around 3 or 4 in every 1,000 births. Regarding spontaneous or natural monozygotic twinning, a 2007 theory related to in vitro fertilization (IVF) proposes that monozygotic twins may be formed when a blastocyst contains two inner cell masses (ICM), each of which will lead to

1932-614: Is now Colombia. They established the Muisca Confederation of many clans, or cacicazgos , that had a free trade network among themselves. Many were goldsmiths and farmers. Other important Pre-Columbian cultures include: the Cañaris (in south central Ecuador), Chimú Empire (1300–1470, Peruvian northern coast), Chachapoyas , and the Aymaran kingdoms (1000–1450, Western Bolivia and southern Peru). Holding their capital at

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2024-480: Is one of the most biodiverse continents on Earth. It is home to many unique species of animals including the llama , anaconda , piranha , jaguar , vicuña , and tapir , and to one of the largest known insects in the world, the Titan beetle . The Amazon rainforests possess high biodiversity , with Brazil estimated to contain 10% of Earth's species . 83% of South America's large mammals ( megafauna ) became extinct at

2116-582: Is the largest country in South America, covering a little less than half of the continent's land area and encompassing around half of the continent's population. The remaining countries and territories are divided among four subregions : the Andean states , Caribbean South America , The Guianas , and the Southern Cone . Physiographically, South America also includes some of the nearby islands. The Dutch ABC islands ( Aruba , Bonaire , and Curaçao ),

2208-419: Is the most common type of twin. Dizygotic twins, like any other siblings, will practically always have different sequences on each chromosome, due to chromosomal crossover during meiosis . Dizygotic twins share on average 50 percent of each other's genes, the same as siblings that are conceived and born at different times. Like any other siblings , dizygotic twins may look similar , particularly as they are

2300-519: The Altiplano , Tiahuanaco or Tiwanaku (100 BC – 1200 AD, Bolivia) managed a large commercial network based on religion. Around the 7th century, both Tiahuanaco and Wari or Huari Empire (600–1200, Central and northern Peru) expanded its influence to all the Andean region, imposing the Huari urbanism and Tiahuanaco religious iconography. The Muisca were the main indigenous civilization in what

2392-586: The Archipelago of San Andrés, Providencia and Santa Catalina ( San Andrés Island , Providencia Island , and Santa Catalina Island etc., which are administered by Colombia ) are politically parts of South American countries but physiographically parts of North America. Other islands often associated with geopolitical South America are the Chiloé Archipelago and Robinson Crusoe Island (both administered by Chile), Easter Island (culturally

2484-820: The Atacama Desert ; the wettest place on earth, López de Micay in Colombia; the largest rainforest, the Amazon rainforest ; the highest capital city, La Paz , Bolivia ; the highest commercially navigable lake in the world, Lake Titicaca ; and, excluding research stations in Antarctica , the world's southernmost permanently inhabited community, Puerto Toro , Chile. South America's major mineral resources are gold, silver, copper, iron ore, tin , and petroleum. These resources have brought high income to its countries, especially in times of war or of rapid economic growth by industrialized countries elsewhere. However,

2576-717: The Bering Land Bridge (now the Bering Strait ) at least 15,000 years ago from the territory that is present-day Russia. They migrated south through North America, and eventually reached South America through the Isthmus of Panama . Amongst the oldest evidence for human presence in South America is the Monte Verde II site in Chile, suggested to date to around 14,500 years ago. From around 13,000 years ago,

2668-634: The Caribbean colonies and Brazil, as European nations built up economically slave-dependent colonies in the New World . Nearly 40% of all African slaves trafficked to the Americas went to Brazil. An estimated 4.9 million slaves from Africa came to Brazil during the period from 1501 to 1866. In contrast to other European colonies in the Americas which mainly used the labor of African slaves, Spanish colonists mainly enslaved indigenous Americans. In 1750,

2760-1030: The Falkland Islands and South Georgia and the South Sandwich Islands ; and one internal territory : French Guiana . The ABC islands of the Dutch Caribbean (north of Venezuela in the Leeward Antilles ), Ascension Island (a part of Saint Helena, Ascension and Tristan da Cunha ), Bouvet Island (a dependency of Norway ), Panama , and the Caribbean island country of Trinidad and Tobago may also be considered parts of South America. South America has an area of 17,840,000 square kilometers (6,890,000 sq mi). Its population as of 2021 has been estimated at more than 434 million. South America ranks fourth in area (after Asia, Africa, and North America) and fifth in population (after Asia, Africa, Europe, and North America). Brazil

2852-470: The Fishtail projectile point style became widespread across South America, with its disappearance around 11,000 years ago coincident with the disappearance of South America's megafauna. Maize was present in northern South America by around 6,000 years ago. By 2000 BC, many agrarian communities had been settled throughout the Andes and the surrounding regions. Fishing became a widespread practice along

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2944-472: The Fortaleza area, contemporaneous with the pyramids of Ancient Egypt , one of the oldest-known civilizations in the Americas and one of the six sites where civilization separately originated in the ancient world. Caral–Supe governing class established a trade network and developed agriculture then followed by Chavín by 900 BC, according to some estimates and archaeological finds. Artifacts were found at

3036-715: The Maracaibo Lake and the mouth of the Orinoco, predominates an equatorial climate of the type Congolese, that also includes parts of the Brazilian territory. The east-central Brazilian plateau has a humid and warm tropical climate. The northern and eastern parts of the Argentine pampas have a humid subtropical climate with dry winters and humid summers of the Chinese type, while the western and eastern ranges have

3128-599: The Orinoco Llanos and in the Guianas Plateau , the precipitation levels go from moderate to high. The Pacific coast of Colombia and northern Ecuador are rainy regions, with Chocó in Colombia being the rainiest place in the world along with the northern slopes of Indian Himalayas. The Atacama Desert, along this stretch of coast, is one of the driest regions in the world. The central and southern parts of Chile are subject to extratropical cyclones , and most of

3220-547: The Portuguese Crown abolished the enslavement of indigenous peoples in colonial Brazil , under the belief that they were unfit for labor and less effective than enslaved Africans. Enslaved Africans were brought to the Americas on slave ships , under inhuman conditions and ill-treatment, and those who survived were sold in slave markets . After independence, all South American countries maintained slavery for some time. The first South American country to abolish slavery

3312-738: The Portuguese Kingdom of Brazil , Dom Pedro I (also Pedro IV of Portugal), son of the Portuguese King Dom João VI , proclaimed the independent Kingdom of Brazil in 1822, which later became the Empire of Brazil . Despite the Portuguese loyalties of garrisons in Bahia , Cisplatina and Pará , independence was diplomatically accepted by Portugal in 1825, on condition of a high compensation paid by Brazil mediated by

3404-665: The South American Plate . South America is home to several superlatives, including the world's highest uninterrupted waterfall , Angel Falls in Venezuela; the highest single-drop waterfall Kaieteur Falls in Guyana; the largest river by volume, the Amazon River ; the longest mountain range, the Andes (whose highest mountain is Aconcagua at 6,962 m or 22,841 ft); the driest non-polar place on earth,

3496-939: The Southern Hemisphere , with a considerably smaller portion in the Northern Hemisphere . It can also be described as the southern subregion of the Americas . South America is bordered on the west by the Pacific Ocean and on the north and east by the Atlantic Ocean ; North America and the Caribbean Sea lie to the northwest. The continent includes twelve sovereign states : Argentina , Bolivia , Brazil , Chile , Colombia , Ecuador , Guyana , Paraguay , Peru , Suriname , Uruguay , and Venezuela ; two dependent territories :

3588-613: The Spanish American wars of independence between the patriots, who promoted such autonomy, and the royalists , who supported Spanish authority over the Americas. The Juntas, in both Spain and the Americas, promoted the ideas of the Enlightenment . Five years after the beginning of the war, Ferdinand VII returned to the throne and began the Absolutist Restoration , as the royalists got the upper hand in

3680-683: The Yoruba to 10% for Linha São Pedro, a tiny Brazilian settlement which belongs to the city of Cândido Godói . In Cândido Godói, one in five pregnancies has resulted in twins. The Argentine historian Jorge Camarasa has put forward the theory that experiments of the Nazi doctor Josef Mengele could be responsible for the high ratio of twins in the area. His theory was rejected by Brazilian scientists who had studied twins living in Linha São Pedro; they suggested genetic factors within that community as

3772-462: The blastocysts have fused. Monochorionic twins share the same placenta , and thus have a risk of twin-to-twin transfusion syndrome . Monoamniotic twins are always monozygotic . The survival rate for monoamniotic twins is somewhere between 50% and 60%. Monoamniotic twins, as with diamniotic monochorionic twins, have a risk of twin-to-twin transfusion syndrome . Also, the two umbilical cords have an increased chance of being tangled around

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3864-712: The native populations had no immune resistance – caused large-scale depopulation of the native population under Spanish control. Systems of forced labor, such as the haciendas and mining industry's mit'a also contributed to the depopulation. After this, enslaved Africans , who had developed immunities to these diseases, were quickly brought in to replace them. The Spaniards were committed to converting their native subjects to Christianity and were quick to purge any native cultural practices that hindered this end; however, many initial attempts at this were only partially successful, as native groups simply blended Catholicism with their established beliefs and practices. Furthermore,

3956-755: The Americas. The continent is generally delimited on the northwest by the Darién watershed along the Colombia–Panama border , although some may consider the border instead to be the Panama Canal . Geopolitically and geographically, all of Panama – including the segment east of the Panama Canal in the isthmus – is typically included in North America alone and among the countries of Central America . Almost all of mainland South America sits on

4048-692: The Argentine Patagonia is desert . In the Pampas of Argentina, Uruguay and South of Brazil the rainfall is moderate, with rains well distributed during the year. The moderately dry conditions of the Chaco oppose the intense rainfall of the eastern region of Paraguay. In the semiarid coast of the Brazilian Northeast the rains are linked to a monsoon regime. Important factors in the determination of climates are sea currents, such as

4140-748: The Breton type and, already in Tierra del Fuego , cold climate of the Siberian type. The distribution of rainfall is related to the regime of winds and air masses. In most of the tropical region east of the Andes, winds blowing from the northeast, east and southeast carry moisture from the Atlantic, causing abundant rainfall. However, due to a consistently strong wind shear and a weak Intertropical Convergence Zone , South Atlantic tropical cyclones are rare. In

4232-499: The South Sandwich Islands ( biogeographically and hydrologically associated with Antarctica) have been administered as two British Overseas Territories under the Crown , whose sovereignty over the islands is disputed by Argentina . An isolated volcanic island on the South American Plate , Ascension Island is geologically a part of South America. Administered as a dependency of Saint Helena, Ascension and Tristan da Cunha ,

4324-1014: The Spaniards brought their language to the degree they did with their religion, although the Roman Catholic Church 's evangelization in Quechua , Aymara , and Guaraní actually contributed to the continuous use of these native languages albeit only in the oral form. Eventually, the natives and the Spaniards interbred, forming a mestizo class. At the beginning, many mestizos of the Andean region were offspring of Amerindian mothers and Spanish fathers. After independence, most mestizos had native fathers and European or mestizo mothers. Many native artworks were considered pagan idols and destroyed by Spanish explorers; this included many gold and silver sculptures and other artifacts found in South America, which were melted down before their transport to Spain or Portugal. Spaniards and Portuguese brought

4416-534: The Spanish and Portuguese colonies. First, Napoleon invaded Portugal, but the House of Braganza avoided capture by escaping to Brazil . Napoleon captured King Ferdinand VII of Spain, and appointed his own brother instead. This appointment provoked popular resistance, which created Juntas to rule in the name of the captured king. Many cities in the Spanish colonies, however, considered themselves equally authorized to appoint local Juntas like those of Spain. This began

4508-480: The United Kingdom and South Africa Twin towns and sister cities , towns and cities involved in town twinning A type of transnational education in which a student does part of their degree course in a local private college and part of it in an overseas institution tied to the college eTwinning , an EU collaboration project in which two schools in different locations are paired and communicate using

4600-423: The United Kingdom. The newly independent nations began a process of fragmentation, with several civil and international wars. However, it was not as strong as in Central America. Some countries created from provinces of larger countries stayed as such up to modern times (such as Paraguay or Uruguay), while others were reconquered and reincorporated into their former countries (such as the Republic of Entre Ríos and

4692-560: The United States rose 76% from 1980 through 2009, from 9.4 to 16.7 twin sets (18.8 to 33.3 twins) per 1,000 births. The Yoruba people have the highest rate of twinning in the world, at 45–50 twin sets (90–100 twins) per 1,000 live births, possibly because of high consumption of a specific type of yam containing a natural phytoestrogen which may stimulate the ovarys to release an egg from each side. In Central Africa , there are 18–30 twin sets (or 36–60 twins) per 1,000 live births. In South America , South Asia , and Southeast Asia ,

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4784-414: The article. Fraternal twins can be any of the following: Among non-twin births, male singletons are slightly (about five percent) more common than female singletons. The rates for singletons vary slightly by country. For example, the sex ratio of birth in the US is 1.05 males/female, while it is 1.07 males/female in Italy. However, males are also more susceptible than females to die in utero , and since

4876-473: The babies. Because of this, there is an increased chance that the newborns may be miscarried or suffer from cerebral palsy due to lack of oxygen. When the division of the developing zygote into 2 embryos occurs, 99% of the time it is within 8 days of fertilization. Mortality is highest for conjoined twins due to the many complications resulting from shared organs. A 2006 study has found that insulin-like growth factor present in dairy products may increase

4968-450: The chance of dizygotic twinning. Specifically, the study found that vegan mothers (who exclude dairy from their diets) are one-fifth as likely to have twins as vegetarian or omnivore mothers, and concluded that "Genotypes favoring elevated IGF and diets including dairy products, especially in areas where growth hormone is given to cattle, appear to enhance the chances of multiple pregnancies due to ovarian stimulation." From 1980 to 1997,

5060-437: The coast, helping establish fish as a primary source of food. Irrigation systems were also developed at this time, which aided in the rise of an agrarian society . South American cultures began domesticating llamas , vicuñas , guanacos , and alpacas in the highlands of the Andes circa 3500 BC. Besides their use as sources of meat and wool, these animals were used for transportation of goods. The rise of plant growing and

5152-461: The concentration in producing one, or few, major export commodities has often hindered the development and diversification of its economies. The fluctuation in the price of commodities in international markets has led historically to major highs and lows, booms and busts, in the economies of South American states, often causing political instability. This has led for calls to diversify production and increase trade within South America itself. Brazil

5244-424: The conflict. The independence of South America was secured by Simón Bolívar (Venezuela) and José de San Martín (Argentina), the two most important Libertadores . Bolívar led a great uprising in the north, then led his army south towards Lima , the capital of the Viceroyalty of Peru . Meanwhile, San Martín led an army across the Andes Mountains, along with Chilean expatriates, and liberated Chile. He organized

5336-405: The current Humboldt and Falklands . The equatorial current of the South Atlantic strikes the coast of the Northeast and there is divided into two others: the current of Brazil and a coastal current that flows to the northwest towards the Antilles , where there it moves towards northeast course thus forming the most Important and famous ocean current in the world, the Gulf Stream . South America

5428-406: The deactivation of different X chromosomes in female monozygotic twins, and in some extremely rare cases, due to aneuploidy , twins may express different sexual phenotypes , normally from an XXY Klinefelter syndrome zygote splitting unevenly. Monozygotic twins, although genetically very similar, are not genetically exactly the same. The DNA in white blood cells of 66 pairs of monozygotic twins

5520-413: The death rate in utero is higher for twins, it leads to female twins being more common than male twins. Zygosity is the degree of identity in the genome of twins. Dizygotic ( DZ ) or fraternal twins (also referred to as "non-identical twins", "dissimilar twins", "biovular twins", and, informally in the case of females, "sororal twins") usually occur when two fertilized eggs are implanted in

5612-408: The differences detected in this study would have occurred during embryonic cell-division (after the point of fertilization). If they occur early in fetal development, they will be present in a very large proportion of body cells. Another cause of difference between monozygotic twins is epigenetic modification , caused by differing environmental influences throughout their lives. Epigenetics refers to

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5704-405: The early stages of embryonic development. A 1981 study of a deceased XXX twin fetus without a heart showed that although its fetal development suggested that it was an identical twin, as it shared a placenta with its healthy twin, tests revealed that it was probably a polar body twin. The authors were unable to predict whether a healthy fetus could result from a polar body twinning. However,

5796-427: The end of the Pleistocene around 11,000 years ago as part of the Quaternary extinction event , among the highest of any continent, with the casualties including saber-toothed cats , ground sloths , glyptodonts , gomphotheres , the equines Hippidion and Equus neogeus , and all remaining South American native ungulates . South America is thought to have been first inhabited by humans when people were crossing

5888-633: The epigenetic difference of three-year-old twins. Twins who had spent their lives apart (such as those adopted by two different sets of parents at birth) had the greatest difference. However, certain characteristics become more alike as twins age, such as IQ and personality. In January 2021, new research from a team of researchers in Iceland was published in the journal Nature Genetics suggesting that identical twins may not be quite as identical as previously thought. The four-year study of monozygotic (identical) twins and their extended families revealed that these twins have genetic differences that begin in

5980-424: The globe. In a study on the maternity records of 5750 Hausa women living in the Savannah zone of Nigeria , there were 40 twins and 2 triplets per 1000 births. Twenty-six percent of twins were monozygotic. The incidence of multiple births, which was about five times higher than that observed in any western population, was significantly lower than that of other ethnic groups, who live in the hot and humid climate of

6072-502: The great city of Cusco , the Inca civilization dominated the Andes region from 1438 to 1533. Known as Tawantin suyu , and "the land of the four regions", in Quechua , the Inca Empire was highly distinct and developed. Inca rule extended to nearly a hundred linguistic or ethnic communities, some nine to fourteen million people connected by a 25,000 kilometer road system . Cities were built with precise, unmatched stonework, constructed over many levels of mountain terrain. Terrace farming

6164-416: The internet Twinning (roads) , construction of one road next to another In crystallography, crystal twinning refers to intergrown crystal forms that display a twin boundary In film, special effects that multiply the presence of the same actor or actress on screen In animation, twinning refers to when two parts on opposite sides of a character's body move the same way Twinning (TV series) ,

6256-417: The island is geopolitically a part of Africa. All of the world's major climate zones are present in South America. The distribution of the average temperatures in the region presents a constant regularity from the 30° of latitude south , when the isotherms tend, more and more, to be confused with the degrees of latitude. In temperate latitudes, winters and summers are milder than in North America. This

6348-487: The islands of Trinidad and Tobago ( Trinidad Island and Tobago Island etc.), the State of Nueva Esparta , and the Federal Dependencies of Venezuela sit on the northern portion of the South American continental shelf and are sometimes considered parts of the continent. Geopolitically, all the island countries and territories in the Caribbean have generally been grouped as a subregion of North America instead. By contrast, Aves Island (administered by Venezuela ) and

6440-466: The land outside Europe should be an exclusive duopoly between the two countries. The treaty established an imaginary line along a north–south meridian 370 leagues west of the Cape Verde Islands , roughly 46° 37' W. In terms of the treaty, all land to the west of the line (known to comprise most of the South American soil) would belong to Spain, and all land to the east, to Portugal. As accurate measurements of longitude were impossible at that time,

6532-536: The level of activity of any particular gene. A gene may become switched on, switched off, or could become partially switched on or off in an individual. This epigenetic modification is triggered by environmental events. Monozygotic twins can have markedly different epigenetic profiles. A study of 80 pairs of monozygotic twins ranging in age from three to 74 showed that the youngest twins have relatively few epigenetic differences. The number of epigenetic differences increases with age. Fifty-year-old twins had over three times

6624-476: The line was not strictly enforced, resulting in a Portuguese expansion of Brazil across the meridian. Beginning in the 1530s, the people and natural resources of South America were repeatedly exploited by foreign conquistadors , first from Spain and later from Portugal. These competing colonial nations claimed the land and resources as their own and divided it into colonies. European infectious diseases ( smallpox , influenza , measles , and typhus ) – to which

6716-406: The lowest mortality risk at about 9 percent, although that is still significantly higher than that of singletons. Monochorionic twins generally have two amniotic sacs (called Monochorionic–Diamniotic "MoDi"), which occurs in 60–70% of the pregnancies with monozygotic twins, and in 0.3% of all pregnancies. Monochorionic-Diamniotic twins are almost always monozygotic, with a few exceptions where

6808-459: The lowest rates are found; only 6 to 9 twin sets per 1,000 live births. North America and Europe have intermediate rates of 9 to 16 twin sets per 1,000 live births. Multiple pregnancies are much less likely to carry to full term than single births, with twin pregnancies lasting on average 37 weeks, three weeks less than full term. Women who have a family history of fraternal twins have a higher chance of producing fraternal twins themselves, as there

6900-458: The mid-17th century. It became a Dutch colony in 1667. The indigenous peoples of the Americas in various European colonies were forced to work in European plantations and mines; along with enslaved Africans who were also introduced in the proceeding centuries via the slave trade . European colonists were heavily dependent on indigenous labor during the initial phases of settlement to maintain

6992-525: The number of twin births in the United States rose 52%. This rise can at least partly be attributed to the increasing popularity of fertility drugs and procedures such as IVF, which result in multiple births more frequently than unassisted fertilizations do. It may also be linked to the increase of growth hormones in food. About 1 in 90 human births (1.1%) results from a twin pregnancy. The rate of dizygotic twinning varies greatly among ethnic groups , ranging as high as about 45 per 1000 births (4.5%) for

7084-414: The occurrence of complications "was found to be more likely with increasing twin-to-twin delivery time interval" and suggested that the interval be kept short, though it noted that the study did not examine causes of complications and did not control for factors such as the level of experience of the obstetrician, the wish of the women giving birth, or the "management strategies" of the procedure of delivering

7176-473: The pregnancy. The timing of this separation determines the chorionicity (the number of placentae) and amniocity (the number of sacs) of the pregnancy. Dichorionic twins either never divided (i.e.: were dizygotic) or they divided within the first 4 days. Monoamnionic twins divide after the first week. In very rare cases, twins become conjoined twins . Non-conjoined monozygotic twins form up to day 14 of embryonic development, but when twinning occurs after 14 days,

7268-408: The rate of monozygotic twins) to 14 and more per thousand in some African countries. Dizygotic twins are also more common for older mothers, with twinning rates doubling in mothers over the age of 35. With the advent of technologies and techniques to assist women in getting pregnant, the rate of fraternals has increased markedly. Monozygotic ( MZ ) or identical twins occur when a single egg

7360-444: The same age. However, dizygotic twins may also look very different from each other (for example, be of opposite sexes). Studies show that there is a genetic proclivity for dizygotic twinning. However, it is only the mother who has any effect on the chances of having such twins; there is no known mechanism for a father to cause the release of more than one ovum . Dizygotic twinning ranges from six per thousand births in Japan (similar to

7452-542: The second twin. There have also been cases in which twins are born a number of days apart. Possibly the worldwide record for the duration of the time gap between the first and the second delivery was the birth of twins 97 days apart in Cologne, Germany, the first of which was born on November 17, 2018. South America South America is a continent entirely in the Western Hemisphere and mostly in

7544-455: The southern part of the country. The incidence of multiple births was related to maternal age but did not bear any association to the climate or prevalence of malaria . Twins are more common in people of African descent. The predisposing factors of monozygotic twinning are unknown. Dizygotic twin pregnancies are slightly more likely when the following factors are present in the woman: Women undergoing certain fertility treatments may have

7636-414: The splitting of a zygote or embryo is unknown. IVF techniques are more likely to create dizygotic twins. For IVF deliveries, there are nearly 21 pairs of twins for every 1,000. Monozygotic twins are genetically nearly identical and they are the same chromosomal sex unless there has been a mutation during development. The children of monozygotic twins test genetically as half-siblings (or full siblings, if

7728-421: The subsequent appearance of permanent human settlements allowed for the multiple and overlapping beginnings of civilizations in South America. One of the earliest known South American civilizations was Caral–Supe , on the central Peruvian coast. Though a pre-ceramic culture, the monumental architecture of Caral–Supe created one of the first cities of the world, generally dated to around 3500 BC, at Huaricanga in

7820-411: The subsistence economy, and natives were often captured by expeditions. The importation of African slaves began midway through the 16th century, but the enslavement of indigenous peoples continued well into the 17th and 18th centuries. The Atlantic slave trade brought enslaved Africans primarily to South American colonies, beginning with the Portuguese since 1502. The main destinations of this phase were

7912-436: The twins will likely be conjoined. Furthermore, there can be various degrees of shared environment of twins in the womb, potentially leading to pregnancy complications . It is a common misconception that two placentas automatically implies dizygotic twins, but if monozygotic twins separate early enough, the arrangement of sacs and placentas in utero is in fact indistinguishable from that of dizygotic twins. DiDi twins have

8004-466: The uterus wall at the same time. When two eggs are independently fertilized by two different sperm cells , fraternal twins result. The two eggs, or ova , form two zygotes , hence the terms dizygotic and biovular . Fraternal twins are, essentially, two ordinary siblings who happen to develop in the womb together and who are born at the same time, since they arise from two separate eggs fertilized by two separate sperm , just like ordinary siblings. This

8096-573: The western European architectural style to the continent, and helped to improve infrastructures like bridges, roads, and the sewer system of the cities they discovered or conquered. They also significantly increased economic and trade relations, not just between the old and new world but between the different South American regions and peoples. Finally, with the expansion of the Portuguese and Spanish languages, many cultures that were previously separated became united through that of Latin American. Guyana

8188-472: Was Chile in 1823, Uruguay in 1830, Bolivia in 1831, Guyana in 1833, Colombia and Ecuador in 1851, Argentina in 1853, Peru and Venezuela in 1854, Suriname in 1863, Paraguay in 1869, and in 1888 Brazil was the last South American nation and the last country in western world to abolish slavery. The European Peninsular War (1807–14), a theater of the Napoleonic Wars , changed the political situation of

8280-633: Was a useful form of agriculture. The Mapuche in Central and Southern Chile resisted the European and Chilean settlers, waging the Arauco War for more than 300 years. In 1494, Portugal and Spain, the two great maritime European powers of that time, on the expectation of new lands being discovered in the west, signed the Treaty of Tordesillas , by which they agreed, with the support of the Pope, that all

8372-420: Was analyzed for 506,786 single-nucleotide polymorphisms known to occur in human populations. Polymorphisms appeared in 2 of the 33 million comparisons, leading the researchers to extrapolate that the blood cells of monozygotic twins may have on the order of one DNA-sequence difference for every 12 million nucleotides, which would imply hundreds of differences across the entire genome. The mutations producing

8464-562: Was initially colonized by the Dutch before coming under British control , though there was a brief period during the Napoleonic Wars when it was occupied by the French . The region was initially partitioned between the Dutch, French and British before fully coming under the control of Britain. Suriname was first explored by the Spanish in the 16th century and then settled by the English in

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