Erhai or Er Lake ( Chinese : 洱海 ; pinyin : Ěrhǎi ), is an alpine fault lake in Dali City , Dali Prefecture , Yunnan province, China . Erhai was also known as Yeyuze ( 叶榆泽 ) or Kunming Lake ( 昆明池 ) in ancient times.
144-469: The character "洱" (er) does not have the same meaning as ear (耳). During the Han to Tang dynasty, there was an ancient ethnic named Kunming Yi or Kunming Barbarian ( 昆明夷 ) lived in the neighbouring region of Erhai lake. Therefore, the lake was also called "Kunming Lake". The Kunming Yi has another name Kun-mi ( 昆弥 ). In the following time, Chinese literature recorded the name "昆弥" as "昆弭" (Kun-mi) that "弭"
288-438: A food chain who lose their prey. "Species coextinction is a manifestation of one of the interconnectednesses of organisms in complex ecosystems ... While coextinction may not be the most important cause of species extinctions, it is certainly an insidious one." Coextinction is especially common when a keystone species goes extinct. Models suggest that coextinction is the most common form of biodiversity loss . There may be
432-644: A limited engagement at Mayi involving the assassination of the Chanyu would throw the Xiongnu realm into chaos and benefit the Han. When this plot failed in 133 BC, Emperor Wu launched a series of massive military invasions into Xiongnu territory. The assault culminated in 119 BC at the Battle of Mobei , when Han commanders Huo Qubing ( d. 117 BC ) and Wei Qing ( d. 106 BC ) forced
576-669: A nautilus to the Royal Society that was more than two feet in diameter, and morphologically distinct from any known living species. Hooke theorized that this was simply because the species lived in the deep ocean and no one had discovered them yet. While he contended that it was possible a species could be "lost", he thought this highly unlikely. Similarly, in 1695, Sir Thomas Molyneux published an account of enormous antlers found in Ireland that did not belong to any extant taxa in that area. Molyneux reasoned that they came from
720-647: A series of military campaigns to quell the Xiongnu. The Xiongnu were eventually defeated and forced to accept a status as Han vassals , and the Xiongnu confederation fragmented. The Han conquered the Hexi Corridor and Inner Asian territory of the Tarim Basin from the Xiongnu, helping to establish the Silk Road . The lands north of the Han's borders were later overrun by the nomadic Xianbei confederation. Emperor Wu also launched successful conquests in
864-415: A species or a population is the variety of genetic information in its living members. A large gene pool (extensive genetic diversity ) is associated with robust populations that can survive bouts of intense selection . Meanwhile, low genetic diversity (see inbreeding and population bottlenecks ) reduces the range of adaptions possible. Replacing native with alien genes narrows genetic diversity within
1008-436: A viable population for species preservation and possible future reintroduction to the wild, through use of carefully planned breeding programs . The extinction of one species' wild population can have knock-on effects, causing further extinctions. These are also called "chains of extinction". This is especially common with extinction of keystone species . A 2018 study indicated that the sixth mass extinction started in
1152-595: A Greek sailor had visited. Emperor Zhang 's ( r. 75–88 AD ) reign came to be viewed by later Eastern Han scholars as the high point of the dynastic house. Subsequent reigns were increasingly marked by eunuch intervention in court politics and their involvement in the violent power struggles of the imperial consort clans . In 92 AD, with the aid of the eunuch Zheng Zhong ( d. 107 AD ), Emperor He ( r. 88–105 AD ) had Empress Dowager Dou ( d. 97 AD ) put under house arrest and her clan stripped of power. This
1296-479: A Lazarus species when extant individuals were described in 2019. Attenborough's long-beaked echidna ( Zaglossus attenboroughi ) is an example of a Lazarus species from Papua New Guinea that had last been sighted in 1962 and believed to be possibly extinct, until it was recorded again in November 2023. Some species currently thought to be extinct have had continued speculation that they may still exist, and in
1440-503: A cascade of coextinction across the trophic levels . Such effects are most severe in mutualistic and parasitic relationships. An example of coextinction is the Haast's eagle and the moa : the Haast's eagle was a predator that became extinct because its food source became extinct. The moa were several species of flightless birds that were a food source for the Haast's eagle. Extinction as
1584-463: A change which debased the value of coinage. Although these reforms provoked considerable opposition, Wang's regime met its ultimate downfall with the massive floods of c. 3 AD and 11 AD. Gradual silt build-up in the Yellow River had raised its water level and overwhelmed the flood control works . The Yellow River split into two new branches: one emptying to the north and
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#17327662273201728-448: A coalition of former officials and officers against Dong, who burned Luoyang to the ground and resettled the court at Chang'an in May 191 AD. Dong Zhuo later poisoned Emperor Shao. Dong was killed by his adopted son Lü Bu ( d. 198 AD ) in a plot hatched by Wang Yun ( d. 192 AD ). Emperor Xian fled from Chang'an in 195 AD to the ruins of Luoyang. Xian
1872-429: A common ancestor with modern horses. Pseudoextinction is much easier to demonstrate for larger taxonomic groups. A Lazarus taxon or Lazarus species refers to instances where a species or taxon was thought to be extinct, but was later rediscovered. It can also refer to instances where large gaps in the fossil record of a taxon result in fossils reappearing much later, although the taxon may have ultimately become extinct at
2016-416: A coup against the eunuchs Hou Lan ( d. 172 AD ), Cao Jie ( d. 181 AD ), and Wang Fu ( 王甫 ). When the plot was uncovered, the eunuchs arrested Empress Dowager Dou ( d. 172 AD ) and Chen Fan. General Zhang Huan ( 張奐 ) favoured the eunuchs. He and his troops confronted Dou Wu and his retainers at the palace gate where each side shouted accusations of treason against
2160-527: A descendant of Emperor Jing ( r. 157–141 BC ), attempted to restore the Han dynasty and occupied Chang'an as his capital. However, he was overwhelmed by the Red Eyebrow rebels who deposed, assassinated, and replaced him with the puppet monarch Liu Penzi . Gengshi's distant cousin Liu Xiu, known posthumously as Emperor Guangwu ( r. 25–57 AD ), after distinguishing himself at
2304-399: A fact that was accepted by most scientists. The primary debate focused on whether this turnover caused by extinction was gradual or abrupt in nature. Cuvier understood extinction to be the result of cataclysmic events that wipe out huge numbers of species, as opposed to the gradual decline of a species over time. His catastrophic view of the nature of extinction garnered him many opponents in
2448-708: A higher risk of extinction and die out faster than less sexually dimorphic species, the least sexually dimorphic species surviving for millions of years while the most sexually dimorphic species die out within mere thousands of years. Earlier studies based on counting the number of currently living species in modern taxa have shown a higher number of species in more sexually dimorphic taxa which have been interpreted as higher survival in taxa with more sexual selection, but such studies of modern species only measure indirect effects of extinction and are subject to error sources such as dying and doomed taxa speciating more due to splitting of habitat ranges into more small isolated groups during
2592-405: A large range, a lack of individuals of both sexes (in sexually reproducing species), or other reasons. Pinpointing the extinction (or pseudoextinction ) of a species requires a clear definition of that species . If it is to be declared extinct, the species in question must be uniquely distinguishable from any ancestor or daughter species, and from any other closely related species. Extinction of
2736-607: A later point. The coelacanth , a fish related to lungfish and tetrapods , is an example of a Lazarus taxon that was known only from the fossil record and was considered to have been extinct since the end of the Cretaceous Period . In 1938, however, a living specimen was found off the Chalumna River (now Tyolomnqa) on the east coast of South Africa. Calliostoma bullatum , a species of deepwater sea snail originally described from fossils in 1844 proved to be
2880-594: A mathematical model that falls in all positions. By contrast, conservation biology uses the extinction vortex model to classify extinctions by cause. When concerns about human extinction have been raised, for example in Sir Martin Rees ' 2003 book Our Final Hour , those concerns lie with the effects of climate change or technological disaster. Human-driven extinction started as humans migrated out of Africa more than 60,000 years ago. Currently, environmental groups and some governments are concerned with
3024-456: A natural part of the evolutionary process. Only recently have extinctions been recorded and scientists have become alarmed at the current high rate of extinctions . Most species that become extinct are never scientifically documented. Some scientists estimate that up to half of presently existing plant and animal species may become extinct by 2100. A 2018 report indicated that the phylogenetic diversity of 300 mammalian species erased during
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#17327662273203168-441: A new mega-predator or by transporting animals and plants from one part of the world to another. Such introductions have been occurring for thousands of years, sometimes intentionally (e.g. livestock released by sailors on islands as a future source of food) and sometimes accidentally (e.g. rats escaping from boats). In most cases, the introductions are unsuccessful, but when an invasive alien species does become established,
3312-664: A number of limited institutional innovations. To finance its military campaigns and the settlement of newly conquered frontier territories, the Han government nationalised private salt and iron industries in 117 BC, creating government monopolies that were later repealed during the Eastern period. There were significant advances in science and technology during the Han period, including the emergence of papermaking , rudders for steering ships, negative numbers in mathematics , raised-relief maps , hydraulic -powered armillary spheres for astronomy , and seismometers that discerned
3456-610: A population a higher chance in the short term of surviving an adverse change in conditions. Effects that cause or reward a loss in genetic diversity can increase the chances of extinction of a species. Population bottlenecks can dramatically reduce genetic diversity by severely limiting the number of reproducing individuals and make inbreeding more frequent. Extinction sometimes results for species evolved to specific ecologies that are subjected to genetic pollution —i.e., uncontrolled hybridization , introgression and genetic swamping that lead to homogenization or out-competition from
3600-407: A race of animals to become extinct. A series of fossils were discovered in the late 17th century that appeared unlike any living species. As a result, the scientific community embarked on a voyage of creative rationalization, seeking to understand what had happened to these species within a framework that did not account for total extinction. In October 1686, Robert Hooke presented an impression of
3744-502: A reduction in agricultural productivity. Furthermore, increased erosion contributes to poorer water quality by elevating the levels of sediment and pollutants in rivers and streams. Habitat degradation through toxicity can kill off a species very rapidly, by killing all living members through contamination or sterilizing them. It can also occur over longer periods at lower toxicity levels by affecting life span, reproductive capacity, or competitiveness. Habitat degradation can also take
3888-578: A request by Kushan ruler Vima Kadphises ( r. c. 90 – c. 100 AD – ) for a marriage alliance with the Han was rejected in AD ;90, he sent his forces to Wakhan (modern-day Afghanistan) to attack Ban Chao. The conflict ended with the Kushans withdrawing because of lack of supplies. In AD 91, the office of Protector General of the Western Regions
4032-499: A result of climate change has been confirmed by fossil studies. Particularly, the extinction of amphibians during the Carboniferous Rainforest Collapse , 305 million years ago. A 2003 review across 14 biodiversity research centers predicted that, because of climate change, 15–37% of land species would be "committed to extinction" by 2050. The ecologically rich areas that would potentially suffer
4176-626: A rich biodiversity in Erhai. It is one of three major Yunnan lakes with a high number of endemics , the two other being Fuxian and Dian (Dianchi). Of the 23 fish species and subspecies known from Erhai, 8 are endemic: Cyprinus barbatus , C. daliensis , C. longipectoralis , C. megalophthalmus , Paracobitis erhaiensis , Poropuntius daliensis ( syn. Barbodes daliensis ), P. exiguus (syn. B. exigua ) and Zacco taliensis (syn. Schizothorax taliensis ). Among these, only C. barbatus and C. longipectoralis have been recorded since
4320-428: A series of reforms that limited the power of these kingdoms in 145, dividing their former territories into new commanderies under central control. Kings were no longer able to appoint their own staff; this duty was assumed by the imperial court. Kings became nominal heads of their fiefs and collected a portion of tax revenues as their personal incomes. The kingdoms were never entirely abolished and existed throughout
4464-479: A species (or replacement by a daughter species) plays a key role in the punctuated equilibrium hypothesis of Stephen Jay Gould and Niles Eldredge . In ecology , extinction is sometimes used informally to refer to local extinction , in which a species ceases to exist in the chosen area of study, despite still existing elsewhere. Local extinctions may be made good by the reintroduction of individuals of that species taken from other locations; wolf reintroduction
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4608-439: A species may come suddenly when an otherwise healthy species is wiped out completely, as when toxic pollution renders its entire habitat unliveable; or may occur gradually over thousands or millions of years, such as when a species gradually loses out in competition for food to better adapted competitors. Extinction may occur a long time after the events that set it in motion, a phenomenon known as extinction debt . Assessing
4752-404: A species or group of species. "Just as each species is unique", write Beverly and Stephen C. Stearns , "so is each extinction ... the causes for each are varied—some subtle and complex, others obvious and simple". Most simply, any species that cannot survive and reproduce in its environment and cannot move to a new environment where it can do so, dies out and becomes extinct. Extinction of
4896-408: A state pension and a territorial fiefdom . Holders of the rank immediately below, that of ordinary marquess, received a pension, but had no territorial rule. Scholar-bureaucrats who served in government belonged to the wider commoner social class and were ranked just below nobles in social prestige. The highest government officials could be enfeoffed as marquesses. Extinct Extinction
5040-518: A subsequent report, IPBES listed unsustainable fishing, hunting and logging as being some of the primary drivers of the global extinction crisis. In June 2019, one million species of plants and animals were at risk of extinction. At least 571 plant species have been lost since 1750, but likely many more. The main cause of the extinctions is the destruction of natural habitats by human activities, such as cutting down forests and converting land into fields for farming. A dagger symbol (†) placed next to
5184-545: A successful overthrow of her regime to enthrone Emperor Shun of Han ( r. 125–144 AD ). Yan was placed under house arrest, her relatives were either killed or exiled, and her eunuch allies were slaughtered. The regent Liang Ji ( d. 159 AD ), brother of Empress Liang Na ( d. 150 AD ), had the brother-in-law of Consort Deng Mengnü ( d. 165 AD ) killed after Deng Mengnü resisted Liang Ji's attempts to control her. Afterward, Emperor Huan employed eunuchs to depose Liang Ji, who
5328-474: A war to determine who would have hegemony over China, which had fissured into Eighteen Kingdoms , each claiming allegiance to either Xiang Yu or Liu Bang. Although Xiang Yu proved to be an effective commander, Liu Bang defeated him at the Battle of Gaixia (202 BC) in modern-day Anhui . Liu Bang assumed the title of Emperor at the urging of his followers and is known posthumously as Emperor Gaozu ( r. 202–195 BC ). Chang'an (modern Xi'an)
5472-451: Is 250 square kilometres (97 sq mi), making it the second largest highland lake in China, after Dianchi Lake . Its circumference reaches 116 kilometres (72 mi), its average depth is of 11 metres (36 ft) and the total storage capacity of 2.5 billion cubic metres (2,000,000 acre⋅ft). The lake serves as a backdrop to all of Dali City and sandwiches Dali Town in
5616-478: Is a rebus of "弥". And the name of the lake was also changed to the character "渳" (mi) which has a water-meaning radical ( 氵 ) attached to it. Fang Guoyu believe the name "洱" (er) was simplified from "渳", after that the name "Erhai" continues to this day. According to Bai scholar's research, the "Yeyu" in the Chinese name "Yeyuze" ( ze [泽] means lake) is evolved from Bai language which means "lower water",
5760-523: Is also evidence to suggest that this event was preceded by another mass extinction, known as Olson's Extinction . The Cretaceous–Paleogene extinction event (K–Pg) occurred 66 million years ago, at the end of the Cretaceous period; it is best known for having wiped out non-avian dinosaurs , among many other species. According to a 1998 survey of 400 biologists conducted by New York 's American Museum of Natural History , nearly 70% believed that
5904-623: Is an accepted version of this page The Han dynasty was an imperial dynasty of China (202 BC – 9 AD, 25–220 AD) established by Liu Bang and ruled by the House of Liu. The dynasty was preceded by the short-lived Qin dynasty (221–206 BC) and a warring interregnum known as the Chu–Han Contention (206–202 BC), and it was succeeded by the Three Kingdoms period (220–280 AD). The dynasty
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6048-444: Is an example of this. Species that are not globally extinct are termed extant . Those species that are extant, yet are threatened with extinction, are referred to as threatened or endangered species . Currently, an important aspect of extinction is human attempts to preserve critically endangered species. These are reflected by the creation of the conservation status "extinct in the wild" (EW) . Species listed under this status by
6192-585: Is difficult to demonstrate unless one has a strong chain of evidence linking a living species to members of a pre-existing species. For example, it is sometimes claimed that the extinct Hyracotherium , which was an early horse that shares a common ancestor with the modern horse , is pseudoextinct, rather than extinct, because there are several extant species of Equus , including zebra and donkey ; however, as fossil species typically leave no genetic material behind, one cannot say whether Hyracotherium evolved into more modern horse species or merely evolved from
6336-417: Is estimated as 100 to 1,000 times "background" rates (the average extinction rates in the evolutionary time scale of planet Earth), faster than at any other time in human history, while future rates are likely 10,000 times higher. However, some groups are going extinct much faster. Biologists Paul R. Ehrlich and Stuart Pimm , among others, contend that human population growth and overconsumption are
6480-493: Is now northern Sichuan and southern Shaanxi , was not quelled until 215 AD. Zhang Jue's massive rebellion across eight provinces was annihilated by Han forces within a year; however, the following decades saw much smaller recurrent uprisings. Although the Yellow Turbans were defeated, many generals appointed during the crisis never disbanded their assembled militias and used these troops to amass power outside of
6624-550: Is recorded in the Weilüe and Book of Later Han to have reached the court of Emperor Huan of Han ( r. 146–168 AD ) in AD 166, yet Rafe de Crespigny asserts that this was most likely a group of Roman merchants . In addition to Roman glasswares and coins found in China, Roman medallions from the reign of Antoninus Pius and his adopted son Marcus Aurelius have been found at Óc Eo in Vietnam. This
6768-592: Is the destruction of ocean floors by bottom trawling . Diminished resources or introduction of new competitor species also often accompany habitat degradation. Global warming has allowed some species to expand their range, bringing competition to other species that previously occupied that area. Sometimes these new competitors are predators and directly affect prey species, while at other times they may merely outcompete vulnerable species for limited resources. Vital resources including water and food can also be limited during habitat degradation, leading to extinction. In
6912-525: Is the most important determinant of genus extinction at background rates but becomes increasingly irrelevant as mass extinction arises. Limited geographic range is a cause both of small population size and of greater vulnerability to local environmental catastrophes. Extinction rates can be affected not just by population size, but by any factor that affects evolvability , including balancing selection , cryptic genetic variation , phenotypic plasticity , and robustness . A diverse or deep gene pool gives
7056-457: Is the termination of a taxon by the death of its last member . A taxon may become functionally extinct before the death of its last member if it loses the capacity to reproduce and recover. Because a species' potential range may be very large, determining this moment is difficult, and is usually done retrospectively. This difficulty leads to phenomena such as Lazarus taxa , where a species presumed extinct abruptly "reappears" (typically in
7200-538: The Battle of Kunyang in 23 AD, was urged to succeed Gengshi as emperor. Under Guangwu's rule, the Han Empire was restored. Guangwu made Luoyang his capital in 25 AD, and by 27 his officers Deng Yu and Feng Yi had forced the Red Eyebrows to surrender and executed their leaders for treason . From 26 until 36 AD, Emperor Guangwu had to wage war against other regional warlords who claimed
7344-462: The Battle of Zhizhi , in modern Taraz , Kazakhstan. In 121 BC, Han forces expelled the Xiongnu from a vast territory spanning the Hexi Corridor to Lop Nur . They repelled a joint Xiongnu- Qiang invasion of this northwestern territory in 111 BC. In that same year, the Han court established four new frontier commanderies in this region to consolidate their control: Jiuquan , Zhangyi , Dunhuang , and Wuwei . The majority of people on
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#17327662273207488-716: The Butterfly Springs on the Western bank. Islands on the lake – including Guanyin Ge , Jinsuo Island ( 金梭岛 ; 'Golden Shuttle Island'), Nanzhao Folklore Island ( 南诏风情岛 ) and Xiaoputuo Island ( 小普陀 ) – are also available for visits. The lake is an important food source for the local people ( Bais ), who are famous for their fishing method: their trained cormorants catch fish and return them to fishmongers. The birds are prevented from swallowing their fish by rings fixed around their neck. There is, or was,
7632-743: The Buyeo Kingdom in Manchuria to the Ili River of the Wusun people. The Xianbei reached their apogee under Tanshihuai ( d. AD 181 ), who consistently defeated Chinese armies. However, Tanshihuai's confederation disintegrated after his death. Ban Chao ( d. AD 102 ) enlisted the aid of the Kushan Empire , which controlled territory across South and Central Asia, to subdue Kashgar and its ally Sogdiana. When
7776-756: The Chu–Han Contention , the resulting Han dynasty was named after the Hanzhong fief. China's first imperial dynasty was the Qin dynasty (221–207 BC). The Qin united the Chinese Warring States by conquest, but their regime became unstable after the death of the first emperor Qin Shi Huang . Within four years, the dynasty's authority had collapsed in a rebellion. Two former rebel leaders, Xiang Yu ( d. 202 BC ) of Chu and Liu Bang ( d. 195 BC ) of Han , engaged in
7920-707: The Greco-Bactrian Kingdom ); he also gathered information on Shendu (the Indus River valley) and Anxi (the Parthian Empire ). All of these countries eventually received Han embassies. These connections marked the beginning of the Silk Road trade network that extended to the Roman Empire , bringing goods like Chinese silk and Roman glasswares between the two. From c. 115 BC until c. 60 BC , Han forces fought
8064-483: The International Union for Conservation of Nature (IUCN) are not known to have any living specimens in the wild and are maintained only in zoos or other artificial environments. Some of these species are functionally extinct, as they are no longer part of their natural habitat and it is unlikely the species will ever be restored to the wild. When possible, modern zoological institutions try to maintain
8208-485: The Late Pleistocene could take up to 5 to 7 million years to restore mammal diversity to what it was before the human era. Extinction of a parent species where daughter species or subspecies are still extant is called pseudoextinction or phyletic extinction. Effectively, the old taxon vanishes, transformed ( anagenesis ) into a successor, or split into more than one ( cladogenesis ). Pseudoextinction
8352-638: The Xiongnu , who were estranged from Han until their leader Bi ( 比 ), a rival claimant to the throne against his cousin Punu ( 蒲奴 ), submitted to Han as a tributary vassal in AD 50. This created two rival Xiongnu states: the Southern Xiongnu led by Bi, an ally of Han, and the Northern Xiongnu led by Punu, an enemy of Han. During the turbulent reign of Wang Mang, China lost control over
8496-575: The Yellow Turban Rebellion and Five Pecks of Rice Rebellion in 184 AD, largely because the court did not want to continue to alienate a significant portion of the gentry class who might otherwise join the rebellions. The Yellow Turbans and Five-Pecks-of-Rice adherents belonged to two different hierarchical Taoist religious societies led by faith healers Zhang Jue ( d. 184 AD ) and Zhang Lu ( d. 216 AD ), respectively. Zhang Lu's rebellion, in what
8640-532: The cosmology of later scholars such as Dong Zhongshu . The Han dynasty oversaw periods of economic prosperity as well as significant growth in the money economy that had first been established during the Zhou dynasty ( c. 1050 – 256 BC). The coinage minted by the central government in 119 BC remained the standard in China until the Tang dynasty (618–907 AD). The period saw
8784-616: The fossil record ) after a period of apparent absence. More than 99% of all species that ever lived on Earth , amounting to over five billion species, are estimated to have died out. It is estimated that there are currently around 8.7 million species of eukaryotes globally, and possibly many times more if microorganisms , like bacteria , are included. Notable extinct animal species include non-avian dinosaurs , saber-toothed cats , dodos , mammoths , ground sloths , thylacines , trilobites , golden toads , and passenger pigeons . Through evolution , species arise through
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#17327662273208928-410: The slender-billed curlew ( Numenius tenuirostris ), not seen since 2007. As long as species have been evolving, species have been going extinct. It is estimated that over 99.9% of all species that ever lived are extinct. The average lifespan of a species is 1–10 million years, although this varies widely between taxa. A variety of causes can contribute directly or indirectly to the extinction of
9072-488: The strata of the Paris basin. They saw alternating saltwater and freshwater deposits, as well as patterns of the appearance and disappearance of fossils throughout the record. From these patterns, Cuvier inferred historic cycles of catastrophic flooding, extinction, and repopulation of the earth with new species. Cuvier's fossil evidence showed that very different life forms existed in the past than those that exist today,
9216-400: The " Han people " or "Han Chinese". The spoken Chinese and written Chinese are referred to respectively as the "Han language" and " Han characters ". The Han emperor was at the pinnacle of Han society and culture . He presided over the Han government but shared power with both the nobility and the appointed ministers who came largely from the scholarly gentry class . The Han Empire
9360-639: The 20 biodiversity goals laid out by the Aichi Biodiversity Targets in 2010, only 6 were "partially achieved" by the deadline of 2020. The report warned that biodiversity will continue to decline if the status quo is not changed, in particular the "currently unsustainable patterns of production and consumption, population growth and technological developments". In a 2021 report published in the journal Frontiers in Conservation Science , some top scientists asserted that even if
9504-451: The Aichi Biodiversity Targets set for 2020 had been achieved, it would not have resulted in a significant mitigation of biodiversity loss. They added that failure of the global community to reach these targets is hardly surprising given that biodiversity loss is "nowhere close to the top of any country's priorities, trailing far behind other concerns such as employment, healthcare, economic growth, or currency stability." For much of history,
9648-618: The Earth is currently in the early stages of a human-caused mass extinction, known as the Holocene extinction . In that survey, the same proportion of respondents agreed with the prediction that up to 20% of all living populations could become extinct within 30 years (by 2028). A 2014 special edition of Science declared there is widespread consensus on the issue of human-driven mass species extinctions. A 2020 study published in PNAS stated that
9792-452: The Han as equal partners in a royal marriage alliance, but the Han were forced to send large amounts of tribute items such as silk clothes, food, and wine to the Xiongnu. Despite the tribute and negotiation between Laoshang Chanyu ( r. 174–160 BC ) and Emperor Wen ( r. 180–157 BC ) to reopen border markets, many of the Chanyu 's subordinates chose not to obey
9936-726: The Imperial University on a dubious charge of treason. In 167 AD, the Grand Commandant Dou Wu ( d. 168 AD ) convinced his son-in-law, Emperor Huan, to release them. However, the emperor permanently barred Li Ying and his associates from serving in office, marking the beginning of the Partisan Prohibitions . Following Huan's death, Dou Wu and the Grand Tutor Chen Fan ( d. 168 AD ) attempted
10080-584: The North American moose and that the animal had once been common on the British Isles . Rather than suggest that this indicated the possibility of species going extinct, he argued that although organisms could become locally extinct, they could never be entirely lost and would continue to exist in some unknown region of the globe. The antlers were later confirmed to be from the extinct deer Megaloceros . Hooke and Molyneux's line of thinking
10224-522: The Paris basin, could be formed by a slow rise and fall of sea levels . The concept of extinction was integral to Charles Darwin 's On the Origin of Species , with less fit lineages disappearing over time. For Darwin, extinction was a constant side effect of competition . Because of the wide reach of On the Origin of Species , it was widely accepted that extinction occurred gradually and evenly (a concept now referred to as background extinction ). It
10368-693: The Tarim Basin, which was conquered by the Northern Xiongnu in AD 63 and used as a base to invade the Hexi Corridor in Gansu . Dou Gu ( d. 88 AD ) defeated the Northern Xiongnu at the Battle of Yiwulu in AD 73, evicting them from Turpan and chasing them as far as Lake Barkol before establishing a garrison at Hami. After the new Protector General of the Western Regions Chen Mu ( d. AD 75 )
10512-514: The Xiongnu court to flee north of the Gobi Desert , and Han forces reached as far north as Lake Baikal . After Wu's reign, Han forces continued to fight the Xiongnu. The Xiongnu leader Huhanye ( r. 58–31 BC ) finally submitted to the Han as a tributary vassal in 51 BC. Huhanye's rival claimant to the throne, Zhizhi Chanyu ( r. 56–36 BC ), was killed by Han forces under Chen Tang and Gan Yanshou ( 甘延壽 ) at
10656-482: The Xiongnu over control of the oasis city-states in the Tarim Basin. The Han was eventually victorious and established the Protectorate of the Western Regions in 60 BC, which dealt with the region's defence and foreign affairs. The Han also expanded southward . The naval conquest of Nanyue in 111 BC expanded the Han realm into what are now modern Guangdong , Guangxi , and northern Vietnam. Yunnan
10800-546: The Yuan brothers, Zhang committed suicide by jumping into the Yellow River. General Dong Zhuo ( d. 192 AD ) found the young emperor and his brother wandering in the countryside. He escorted them safely back to the capital and was made Minister of Works , taking control of Luoyang and forcing Yuan Shao to flee. After Dong Zhuo demoted Emperor Shao and promoted his brother Liu Xie as Emperor Xian, Yuan Shao led
10944-429: The accumulation of slightly deleterious mutations , then a population will go extinct. Smaller populations have fewer beneficial mutations entering the population each generation, slowing adaptation. It is also easier for slightly deleterious mutations to fix in small populations; the resulting positive feedback loop between small population size and low fitness can cause mutational meltdown . Limited geographic range
11088-528: The capital was moved eastward to Luoyang. The era from his reign until the fall of Han is known as the Eastern Han or Later Han (25–220 AD). The Eastern Han ( traditional Chinese : 東漢 ; simplified Chinese : 东汉 ; pinyin : Dōnghàn ), also known as the Later Han ( 後漢 ; 后汉 ; Hòuhàn ), formally began on 5 August AD 25, when Liu Xiu became Emperor Guangwu of Han . During
11232-491: The cardinal direction of distant earthquakes by use of inverted pendulums . The Han dynasty had many conflicts with the Xiongnu , a nomadic confederation centred in the eastern Eurasian steppe . The Xiongnu defeated the Han in 200 BC , prompting the Han to appease the Xiongnu with a policy of marriage alliance and payments of tribute, though the Xiongnu continued to raid the Han's northern borders. Han policy changed in 133 BC, under Emperor Wu , when Han forces began
11376-434: The collapsing imperial authority. General-in-chief He Jin ( d. 189 AD ), half-brother to Empress He ( d. 189 AD ), plotted with Yuan Shao ( d. 202 AD ) to overthrow the eunuchs by having several generals march to the outskirts of the capital. There, in a written petition to Empress He, they demanded the eunuchs' execution. After a period of hesitation, Empress He consented. When
11520-600: The consequences can be catastrophic. Invasive alien species can affect native species directly by eating them, competing with them, and introducing pathogens or parasites that sicken or kill them; or indirectly by destroying or degrading their habitat. Human populations may themselves act as invasive predators. According to the "overkill hypothesis", the swift extinction of the megafauna in areas such as Australia (40,000 years before present), North and South America (12,000 years before present), Madagascar , Hawaii (AD 300–1000), and New Zealand (AD 1300–1500), resulted from
11664-418: The contemporary extinction crisis "may be the most serious environmental threat to the persistence of civilization, because it is irreversible." Biologist E. O. Wilson estimated in 2002 that if current rates of human destruction of the biosphere continue, one-half of all plant and animal species of life on earth will be extinct in 100 years. More significantly, the current rate of global species extinctions
11808-476: The deliberate destruction of some species, such as dangerous viruses , and the total destruction of other problematic species has been suggested. Other species were deliberately driven to extinction, or nearly so, due to poaching or because they were "undesirable", or to push for other human agendas. One example was the near extinction of the American bison , which was nearly wiped out by mass hunts sanctioned by
11952-490: The emperor was often a minor, ruled over by a regent such as the empress dowager or one of her male relatives. Ranked immediately below the emperor were the kings who were of the same Liu family clan. The rest of society, including nobles lower than kings and all commoners excluding slaves, belonged to one of twenty ranks ( ershi gongcheng 二十公乘 ). Each successive rank gave its holder greater pensions and legal privileges. The highest rank, of full marquess , came with
12096-593: The empire . The Han dynasty came to an end in 220 AD when Cao Pi , king of Wei , usurped the throne from Emperor Xian . According to the Records of the Grand Historian , after the collapse of the Qin dynasty the hegemon Xiang Yu appointed Liu Bang as prince of the small fief of Hanzhong , named after its location on the Han River (in modern southwest Shaanxi ). Following Liu Bang's victory in
12240-489: The empresses and empresses dowager . Imperial authority was also seriously challenged by large Taoist religious societies which instigated the Yellow Turban Rebellion and the Five Pecks of Rice Rebellion . Following the death of Emperor Ling ( r. 168–189 AD ), the palace eunuchs were massacred by military officers, allowing members of the aristocracy and military governors to become warlords and divide
12384-403: The endangered wild water buffalo is most threatened with extinction by genetic pollution from the abundant domestic water buffalo ). Such extinctions are not always apparent from morphological (non-genetic) observations. Some degree of gene flow is a normal evolutionary process; nevertheless, hybridization (with or without introgression) threatens rare species' existence. The gene pool of
12528-640: The eunuchs discovered this, however, they had her brother He Miao ( 何苗 ) rescind the order. The eunuchs assassinated He Jin on 22 September 189. Yuan Shao then besieged Luoyang's Northern Palace while his brother Yuan Shu ( d. 199 AD ) besieged the Southern Palace. On September 25 both palaces were breached and approximately two thousand eunuchs were killed. Zhang Rang had previously fled with Emperor Shao ( r. 189 AD ) and his brother Liu Xie—the future Emperor Xian of Han ( r. 189–220 AD ). While being pursued by
12672-591: The event of rediscovery would be considered Lazarus species. Examples include the thylacine , or Tasmanian tiger ( Thylacinus cynocephalus ), the last known example of which died in Hobart Zoo in Tasmania in 1936; the Japanese wolf ( Canis lupus hodophilax ), last sighted over 100 years ago; the American ivory-billed woodpecker ( Campephilus principalis ), with the last universally accepted sighting in 1944; and
12816-443: The extinction crisis. According to the International Union for Conservation of Nature (IUCN), 784 extinctions have been recorded since the year 1500, the arbitrary date selected to define "recent" extinctions, up to the year 2004; with many more likely to have gone unnoticed. Several species have also been listed as extinct since 2004. If adaptation increasing population fitness is slower than environmental degradation plus
12960-475: The extinction of species caused by humanity, and they try to prevent further extinctions through a variety of conservation programs. Humans can cause extinction of a species through overharvesting , pollution , habitat destruction , introduction of invasive species (such as new predators and food competitors ), overhunting, and other influences. Explosive, unsustainable human population growth and increasing per capita consumption are essential drivers of
13104-427: The family inheritance. His brothers Yuan Shang and Yuan Xi were killed in 207 AD by Gongsun Kang ( d. 221 AD ), who sent their heads to Cao Cao. After Cao's defeat at the naval Battle of Red Cliffs in 208 AD, China was divided into three spheres of influence, with Cao Cao dominating the north, Sun Quan (182–252 AD) dominating the south, and Liu Bei (161–223 AD) dominating
13248-540: The field of zoology , and biology in general, and has also become an area of concern outside the scientific community. A number of organizations, such as the Worldwide Fund for Nature , have been created with the goal of preserving species from extinction. Governments have attempted, through enacting laws, to avoid habitat destruction, agricultural over-harvesting, and pollution . While many human-caused extinctions have been accidental, humans have also engaged in
13392-435: The form of a physical destruction of niche habitats. The widespread destruction of tropical rainforests and replacement with open pastureland is widely cited as an example of this; elimination of the dense forest eliminated the infrastructure needed by many species to survive. For example, a fern that depends on dense shade for protection from direct sunlight can no longer survive without forest to shelter it. Another example
13536-601: The frontier were soldiers. On occasion, the court forcibly moved peasant farmers to new frontier settlements, along with government-owned slaves and convicts who performed hard labour. The court also encouraged commoners, such as farmers, merchants, landowners, and hired labourers, to voluntarily migrate to the frontier. Even before the Han's expansion into Central Asia, diplomat Zhang Qian 's travels from 139 to 125 BC had established Chinese contacts with many surrounding civilizations. Zhang encountered Dayuan ( Fergana ), Kangju ( Sogdiana ), and Daxia ( Bactria , formerly
13680-580: The habitat retreat of taxa approaching extinction. Possible causes of the higher extinction risk in species with more sexual selection shown by the comprehensive fossil studies that rule out such error sources include expensive sexually selected ornaments having negative effects on the ability to survive natural selection , as well as sexual selection removing a diversity of genes that under current ecological conditions are neutral for natural selection but some of which may be important for surviving climate change. There have been at least five mass extinctions in
13824-676: The heaviest losses include the Cape Floristic Region and the Caribbean Basin . These areas might see a doubling of present carbon dioxide levels and rising temperatures that could eliminate 56,000 plant and 3,700 animal species. Climate change has also been found to be a factor in habitat loss and desertification . Studies of fossils following species from the time they evolved to their extinction show that species with high sexual dimorphism , especially characteristics in males that are used to compete for mating, are at
13968-447: The history of life on earth, and four in the last 350 million years in which many species have disappeared in a relatively short period of geological time. A massive eruptive event that released large quantities of tephra particles into the atmosphere is considered to be one likely cause of the " Permian–Triassic extinction event " about 250 million years ago, which is estimated to have killed 90% of species then existing. There
14112-475: The human era since the Late Pleistocene would require 5 to 7 million years to recover. According to the 2019 Global Assessment Report on Biodiversity and Ecosystem Services by IPBES , the biomass of wild mammals has fallen by 82%, natural ecosystems have lost about half their area and a million species are at risk of extinction—all largely as a result of human actions. Twenty-five percent of plant and animal species are threatened with extinction. In
14256-431: The introduced ( or hybrid ) species. Endemic populations can face such extinctions when new populations are imported or selectively bred by people, or when habitat modification brings previously isolated species into contact. Extinction is likeliest for rare species coming into contact with more abundant ones; interbreeding can swamp the rarer gene pool and create hybrids, depleting the purebred gene pool (for example,
14400-488: The main drivers of the modern extinction crisis. In January 2020, the UN's Convention on Biological Diversity drafted a plan to mitigate the contemporary extinction crisis by establishing a deadline of 2030 to protect 30% of the Earth's land and oceans and reduce pollution by 50%, with the goal of allowing for the restoration of ecosystems by 2050. The 2020 United Nations ' Global Biodiversity Outlook report stated that of
14544-421: The modern understanding of extinction as the end of a species was incompatible with the prevailing worldview. Prior to the 19th century, much of Western society adhered to the belief that the world was created by God and as such was complete and perfect. This concept reached its heyday in the 1700s with the peak popularity of a theological concept called the great chain of being , in which all life on earth, from
14688-490: The name of a species or other taxon normally indicates its status as extinct. Examples of species and subspecies that are extinct include: A species is extinct when the last existing member dies. Extinction therefore becomes a certainty when there are no surviving individuals that can reproduce and create a new generation. A species may become functionally extinct when only a handful of individuals survive, which cannot reproduce due to poor health, age, sparse distribution over
14832-469: The natural course of events, species become extinct for a number of reasons, including but not limited to: extinction of a necessary host, prey or pollinator, interspecific competition , inability to deal with evolving diseases and changing environmental conditions (particularly sudden changes) which can act to introduce novel predators, or to remove prey. Recently in geological time, humans have become an additional cause of extinction of some species, either as
14976-410: The newly emerging school of uniformitarianism . Jean-Baptiste Lamarck , a gradualist and colleague of Cuvier, saw the fossils of different life forms as evidence of the mutable character of species. While Lamarck did not deny the possibility of extinction, he believed that it was exceptional and rare and that most of the change in species over time was due to gradual change. Unlike Cuvier, Lamarck
15120-459: The nobility, Wang Mang claimed on 10 January that the divine Mandate of Heaven called for the end of the Han dynasty and the beginning of his own: the Xin dynasty (9–23 AD). Wang Mang initiated a series of major reforms that were ultimately unsuccessful. These reforms included outlawing slavery, nationalizing and equally distributing land between households, and introducing new currencies,
15264-399: The original population, thereby increasing the chance of extinction. Habitat degradation is currently the main anthropogenic cause of species extinctions. The main cause of habitat degradation worldwide is agriculture, with urban sprawl , logging, mining, and some fishing practices close behind. The degradation of a species' habitat may alter the fitness landscape to such an extent that
15408-687: The other to the south of the Shandong Peninsula , though Han engineers managed to dam the southern branch by 70 AD. The flood dislodged thousands of peasant farmers, many of whom joined roving bandit and rebel groups such as the Red Eyebrows to survive. Wang Mang's armies were incapable of quelling these enlarged rebel groups. Eventually, an insurgent mob forced their way into the Weiyang Palace and killed Wang Mang. The Gengshi Emperor ( r. 23–25 AD ),
15552-560: The other. When the retainers gradually deserted Dou Wu, he was forced to commit suicide. Under Emperor Ling ( r. 168–189 AD ) the eunuchs had the partisan prohibitions renewed and expanded, while also auctioning off top government offices. Many affairs of state were entrusted to the eunuchs Zhao Zhong ( d. 189 AD ) and Zhang Rang ( d. 189 AD ) while Emperor Ling spent much of his time roleplaying with concubines and participating in military parades. The Partisan Prohibitions were repealed during
15696-702: The process of speciation —where new varieties of organisms arise and thrive when they are able to find and exploit an ecological niche —and species become extinct when they are no longer able to survive in changing conditions or against superior competition . The relationship between animals and their ecological niches has been firmly established. A typical species becomes extinct within 10 million years of its first appearance, although some species, called living fossils , survive with little to no morphological change for hundreds of millions of years. Mass extinctions are relatively rare events; however, isolated extinctions of species and clades are quite common, and are
15840-626: The pronunciation written in IPA as /jɛji/ . In the Bai language Dali dialect, the "lower" ( /jɛ/ ) is also pronounced /ɛɹ/ . Xu Lin believe the Chinese name "洱" is evolved from /ɛɹ/ . Erhai is situated at 1,972 metres (6,470 ft) above sea level. In size, the North-South length of the lake is 40 kilometres (25 mi) and the East-West width is roughly 7–8 kilometres (4.3–5.0 mi). Its area
15984-410: The relative importance of genetic factors compared to environmental ones as the causes of extinction has been compared to the debate on nature and nurture . The question of whether more extinctions in the fossil record have been caused by evolution or by competition or by predation or by disease or by catastrophe is a subject of discussion; Mark Newman, the author of Modeling Extinction , argues for
16128-603: The remainder of Western and Eastern Han. To the north of China proper , the nomadic Xiongnu chieftain Modu Chanyu ( r. 209–174 BC ) conquered various tribes inhabiting the eastern portion of the Eurasian Steppe . By the end of his reign, he controlled the Inner Asian regions of Manchuria , Mongolia , and the Tarim Basin , subjugating over twenty states east of Samarkand . Emperor Gaozu
16272-616: The salt and iron monopolies were eventually abolished in the early Eastern Han. The issuing of coinage remained a central government monopoly throughout the rest of the Han dynasty. The government monopolies were eventually repealed when a political faction known as the Reformists gained greater influence in the court. The Reformists opposed the Modernist faction that had dominated court politics in Emperor Wu's reign and during
16416-479: The south , annexing Nanyue in 111 BC and Dian in 109 BC . He further expanded Han territory into the northern Korean Peninsula , where Han forces conquered Gojoseon and established the Xuantu and Lelang commanderies in 108 BC. After 92 AD, palace eunuchs increasingly involved themselves in the dynasty's court politics, engaging in violent power struggles between various consort clans of
16560-460: The species is no longer able to survive and becomes extinct. This may occur by direct effects, such as the environment becoming toxic , or indirectly, by limiting a species' ability to compete effectively for diminished resources or against new competitor species. Habitat destruction, particularly the removal of vegetation that stabilizes soil, enhances erosion and diminishes nutrient availability in terrestrial ecosystems. This degradation can lead to
16704-479: The subsequent regency of Huo Guang ( d. 68 BC ). The Modernists argued for an aggressive and expansionary foreign policy supported by revenues from heavy government intervention in the private economy. The Reformists, however, overturned these policies, favouring a cautious, non-expansionary approach to foreign policy, frugal budget reform, and lower tax-rates imposed on private entrepreneurs. Wang Zhengjun (71 BC – 13 AD)
16848-430: The sudden introduction of human beings to environments full of animals that had never seen them before and were therefore completely unadapted to their predation techniques. Coextinction refers to the loss of a species due to the extinction of another; for example, the extinction of parasitic insects following the loss of their hosts. Coextinction can also occur when a species loses its pollinator , or to predators in
16992-412: The tiniest microorganism to God, is linked in a continuous chain. The extinction of a species was impossible under this model, as it would create gaps or missing links in the chain and destroy the natural order. Thomas Jefferson was a firm supporter of the great chain of being and an opponent of extinction, famously denying the extinction of the woolly mammoth on the grounds that nature never allows
17136-461: The title of emperor; when these warlords were defeated, China reunified under the Han. The period between the foundation of the Han dynasty and Wang Mang's reign is known as the Western Han ( 西漢 ; 西汉 ; Xīhàn ) or Former Han ( 前漢 ; 前汉 ; Qiánhàn ) (206 BC – 9 AD). During this period the capital was at Chang'an (modern Xi'an ). From the reign of Guangwu
17280-567: The total extinction of the dodo and the extirpation of indigenous horses to the British Isles. He similarly argued against mass extinctions , believing that any extinction must be a gradual process. Lyell also showed that Cuvier's original interpretation of the Parisian strata was incorrect. Instead of the catastrophic floods inferred by Cuvier, Lyell demonstrated that patterns of saltwater and freshwater deposits , like those seen in
17424-472: The treaty and periodically raided Han territories south of the Great Wall for additional goods. In a court conference assembled by Emperor Wu ( r. 141–87 BC ) in 135 BC, the majority consensus of the ministers was to retain the heqin agreement. Emperor Wu accepted this, despite continuing Xiongnu raids. However, a court conference the following year convinced the majority that
17568-517: The war with Chu, Emperor Gaozu enfeoffed some of them as kings. By 196, the Han court had replaced all of these kings with royal Liu family members, with the lone exception of Changsha . The loyalty of non-relatives to the emperor was questioned, and after several insurrections by Han kings—with the largest being the Rebellion of the Seven States in 154—the imperial court began enacting
17712-801: The west against the Cang Mountain . The lake's head is at Shangguan Town , its northern extremity, and its southernmost point is at Xiaguan Town. The lake receives water from the Miju and Mici Rivers in the north, the Bolou River in the east, and smaller streams from the Cang Mountains in the west. Yangbi River , to the south, is the lake's outlet and eventually flows into the Lancang River ( Mekong River ). The lakeshore can be explored by hiking. Highlights include Erhai Park and
17856-487: The west. Cao Cao died in March 220 AD. By December his son Cao Pi (187–226 AD) had Emperor Xian relinquish the throne to him and is known posthumously as Emperor Wen of Wei . This formally ended the Han dynasty and initiated an age of conflict between the Three Kingdoms : Cao Wei , Eastern Wu , and Shu Han . In the hierarchical social order, the emperor was at the apex of Han society and government. However,
18000-581: The wider scientific community of his theory. Cuvier was a well-regarded geologist, lauded for his ability to reconstruct the anatomy of an unknown species from a few fragments of bone. His primary evidence for extinction came from mammoth skulls found in the Paris basin . Cuvier recognized them as distinct from any known living species of elephant, and argued that it was highly unlikely such an enormous animal would go undiscovered. In 1812, Cuvier, along with Alexandre Brongniart and Geoffroy Saint-Hilaire , mapped
18144-411: The widespread rebellion against Wang Mang , the state of Goguryeo was free to raid Han's Korean commanderies ; Han did not reaffirm its control over the region until AD 30. The Trưng Sisters of Vietnam rebelled against Han in AD 40. Their rebellion was crushed by Han general Ma Yuan ( d. AD 49 ) in a campaign from AD 42 to 43. Wang Mang renewed hostilities against
18288-469: The year 2000; the remaining have not been recorded in decades and are likely extinct . A few of the non-endemic natives have also been extirpated from the lake. In contrast, the lake is now home to more than 10 introduced fish species. A few native hydrophytes have also disappeared from the lake. The lake used to be a royal deer ranch for the Nanzhao Kingdom. Han dynasty This
18432-438: Was appointed regent as Marshall of State on 16 August under Emperor Ping ( r. 1 BC – 6 AD). When Ping died on 3 February 6 AD, Ruzi Ying ( d. 25 AD ) was chosen as the heir and Wang Mang was appointed to serve as acting emperor for the child. Wang promised to relinquish his control to Liu Ying once he came of age. Despite this promise, and against protest and revolts from
18576-589: Was briefly interrupted by the Xin dynasty (9–23 AD) established by the usurping regent Wang Mang , and is thus separated into two periods—the Western Han (202 BC – 9 AD) and the Eastern Han (25–220 AD). Spanning over four centuries, the Han dynasty is considered a golden age in Chinese history , and had a permanent impact on Chinese identity in later periods. The majority ethnic group of modern China refer to themselves as
18720-903: Was brought into the Han realm with the conquest of the Dian Kingdom in 109 BC, followed by parts of the Korean Peninsula with the Han conquest of Gojoseon and establishment of the Xuantu and Lelang commanderies in 108 BC. The first nationwide census in Chinese history was taken in 2 AD; the Han's total population was registered as comprising 57,671,400 individuals across 12,366,470 households. To pay for his military campaigns and colonial expansion, Emperor Wu nationalised several private industries. He created central government monopolies administered largely by former merchants . These monopolies included salt, iron, and liquor production, as well as bronze coinage . The liquor monopoly lasted only from 98 to 81 BC, and
18864-552: Was chosen as the new capital of the reunified empire under Han. At the beginning of the Western Han ( traditional Chinese : 西漢 ; simplified Chinese : 西汉 ; pinyin : Xīhàn ), also known as the Former Han ( 前漢 ; 前汉 ; Qiánhàn ), thirteen centrally-controlled commanderies —including the capital region—existed in the western third of the empire, while the eastern two-thirds were divided into ten semi-autonomous kingdoms . To placate his prominent commanders from
19008-490: Was convinced by the accusations of the eunuchs Li Run ( 李閏 ) and Jiang Jing ( 江京 ) that Deng and her family had planned to depose him. An dismissed Deng's clan members from office, exiled them, and forced many to commit suicide. After An's death, his wife, Empress Dowager Yan ( d. 126 AD ) placed the child Marquess of Beixiang on the throne in an attempt to retain power within her family. However, palace eunuch Sun Cheng ( d. 132 AD ) masterminded
19152-491: Was difficult to disprove. When parts of the world had not been thoroughly examined and charted, scientists could not rule out that animals found only in the fossil record were not simply "hiding" in unexplored regions of the Earth. Georges Cuvier is credited with establishing the modern conception of extinction in a 1796 lecture to the French Institute , though he would spend most of his career trying to convince
19296-442: Was divided into areas directly controlled by the central government called commanderies , as well as a number of semi-autonomous kingdoms . These kingdoms gradually lost all vestiges of their independence, particularly following the Rebellion of the Seven States . From the reign of Emperor Wu ( r. 141–87 BC ) onward, the Chinese court officially sponsored Confucianism in education and court politics, synthesized with
19440-487: Was first empress, then empress dowager , and finally grand empress dowager during the reigns of the Emperors Yuan ( r. 49–33 BC ), Cheng ( r. 33–7 BC ), and Ai ( r. 7–1 BC ), respectively. During this time, a succession of her male relatives held the title of regent. Following the death of Ai, Wang Zhengjun's nephew Wang Mang (45 BC – 23 AD)
19584-446: Was in revenge for Dou's purging of the clan of his natural mother— Consort Liang —and then concealing her identity from him. After Emperor He's death, his wife Empress Deng Sui ( d. 121 AD ) managed state affairs as the regent empress dowager during a turbulent financial crisis and widespread Qiang rebellion that lasted from 107 to 118 AD. When Empress Dowager Deng died, Emperor An ( r. 106–125 AD )
19728-650: Was killed by allies of the Xiongnu in Karasahr and Kucha , the garrison at Hami was withdrawn. At the Battle of Ikh Bayan in AD 89, Dou Xian ( d. AD 92 ) defeated the Northern Xiongnu chanyu who then retreated into the Altai Mountains . After the Northern Xiongnu fled into the Ili River valley in AD 91, the nomadic Xianbei occupied the area from the borders of
19872-664: Was near the commandery of Rinan where Chinese sources claim the Romans first landed, as well as embassies from Tianzhu in northern India in 159 and 161. Óc Eo is also thought to be the port city " Cattigara " described by Ptolemy in his Geography ( c. 150 AD ) as lying east of the Golden Chersonese ( Malay Peninsula ) along the Magnus Sinus (i.e. the Gulf of Thailand and South China Sea ), where
20016-430: Was not until 1982, when David Raup and Jack Sepkoski published their seminal paper on mass extinctions, that Cuvier was vindicated and catastrophic extinction was accepted as an important mechanism . The current understanding of extinction is a synthesis of the cataclysmic extinction events proposed by Cuvier, and the background extinction events proposed by Lyell and Darwin. Extinction is an important research topic in
20160-450: Was persuaded by Cao Cao (155–220 AD), then Governor of Yan Province in modern western Shandong and eastern Henan , to move the capital to Xuchang in 196 AD. Yuan Shao challenged Cao Cao for control over the emperor. Yuan's power was greatly diminished after Cao defeated him at the Battle of Guandu in 200 AD. After Yuan died, Cao killed Yuan Shao's son Yuan Tan (173–205 AD), who had fought with his brothers over
20304-595: Was reinstated when it was bestowed on Ban Chao. Foreign travellers to the Eastern Han empire included Buddhist monks who translated works into Chinese , such as An Shigao from Parthia, and Lokaksema from Kushan-era Gandhara . In addition to tributary relations with the Kushans, the Han empire received gifts from sovereigns in the Parthian Empire , as well as from kings in modern Burma and Japan . He also initiated an unsuccessful mission to Rome in AD 97 with Gan Ying as emissary. A Roman embassy of Emperor Marcus Aurelius ( r. 161–180 AD )
20448-571: Was skeptical that catastrophic events of a scale large enough to cause total extinction were possible. In his geological history of the earth titled Hydrogeologie, Lamarck instead argued that the surface of the earth was shaped by gradual erosion and deposition by water, and that species changed over time in response to the changing environment. Charles Lyell , a noted geologist and founder of uniformitarianism , believed that past processes should be understood using present day processes. Like Lamarck, Lyell acknowledged that extinction could occur, noting
20592-413: Was then forced to commit suicide. Students from the imperial university organized a widespread student protest against the eunuchs of Emperor Huan's court. Huan further alienated the bureaucracy when he initiated grandiose construction projects and hosted thousands of concubines in his harem at a time of economic crisis. Palace eunuchs imprisoned the official Li Ying ( 李膺 ) and his associates from
20736-399: Was troubled about the abundant Han-manufactured iron weapons traded to the Xiongnu along the northern borders, and he established a trade embargo against the group. In retaliation, the Xiongnu invaded what is now Shanxi , where they defeated the Han forces at Baideng in 200 BC. After negotiations, the heqin agreement in 198 BC nominally held the leaders of the Xiongnu and
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