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BERINGIA is defined today as the land and maritime area bounded on the west by the Lena River
Lena River
in Russia
Russia
; on the east by the Mackenzie River in Canada
Canada
; on the north by 72 degrees north latitude in the Chukchi Sea
Chukchi Sea
; and on the south by the tip of the Kamchatka Peninsula
Kamchatka Peninsula
. It includes the Chukchi Sea
Chukchi Sea
, the Bering Sea
Bering Sea
, the Bering Strait
Bering Strait
, the Chukchi and Kamchatka Peninsulas in Russia
Russia
as well as Alaska
Alaska
in the United States
United States
.

The area includes land lying on the North American Plate and Siberian land east of the Chersky Range . Historically, it formed a land bridge that was up to 1,000 kilometres (620 miles) wide at its greatest extent and which covered an area as large as British Columbia
British Columbia
and Alberta
Alberta
together, totaling approximately 1,600,000 square kilometres (620,000 square miles). Today, the only land that is visible from the central part of the Bering land bridge are the Diomede Islands
Diomede Islands
, the Pribilof Islands of St. Paul and St. George, St. Lawrence Island , and King Island .

The term Beringia
Beringia
was coined by the Swedish botanist Eric Hultén in 1937. During the ice ages, Beringia, like most of Siberia
Siberia
and all of North and Northeast China
Northeast China
, was not glaciated because snowfall was very light . It was a grassland steppe , including the land bridge, that stretched for hundreds of kilometres into the continents on either side.

It is believed that a small human population of at most a few thousand arrived in Beringia
Beringia
from eastern Siberia
Siberia
during the Last Glacial Maximum before expanding into the settlement of the Americas sometime after 16,500 years ago during the Late Glacial Maximum as the American glaciers blocking the way southward melted, but before the bridge was covered by the sea about 11,000 years BP .

Before European colonization, Beringia
Beringia
was inhabited by the Yupik peoples on both sides of the straits. This culture remains in the region today along with others. In 2012, the governments of Russia
Russia
and the United States
United States
announced a plan to formally establish "a transboundary area of shared Beringian heritage". Among other things this agreement would establish close ties between the Bering Land Bridge National Preserve and the Cape Krusenstern National Monument
Cape Krusenstern National Monument
in the United States
United States
and the planned Beringia National Park in Russia.

CONTENTS

* 1 Geography * 2 Beringian refugium * 3 Human habitation * 4 Previous connections * 5 See also * 6 References * 7 Further reading * 8 External links

GEOGRAPHY

Bering land bridge – Wisconsin glaciation
Wisconsin glaciation
Bering land bridge region – deglaciation period Bering land bridge region – present day

The remains of Late Pleistocene mammals that had been discovered on the Aleutians
Aleutians
and islands in the Bering Sea
Bering Sea
at the close of the nineteenth century indicated that a past land connection might lie beneath the shallow waters between Alaska
Alaska
and Chukotka . The underlying mechanism was first thought to be tectonics, but by 1930 changes in the icemass balance, leading to global sea-level fluctuations, was viewed as the cause of the Bering Land Bridge. In 1937, Eric Hultén proposed that around the Aleutians
Aleutians
and the Bering Strait region were tundra plants that had originally dispersed from a now-submerged plain between Alaska
Alaska
and Chukotka, which he named Beringia
Beringia
after Vitus Bering
Vitus Bering
who had sailed into the strait in 1728. The American arctic geologist David Hopkins redefined Beringia
Beringia
to include portions of Alaska
Alaska
and Northeast Asia. Beringia
Beringia
was later regarded as extending from the Verkhoyansk Mountains in the west to the Mackenzie River
Mackenzie River
in the east. The distribution of plants in the genera Erythranthe and Pinus are good examples of this as genera members are found in Asia
Asia
and the Americas with a high degree of similarity.

During the Pleistocene
Pleistocene
epoch, global cooling led periodically to the expansion of glaciers and lowering of sea levels. This created land connections in various regions around the globe. Today, the average water depth of the Bering Strait
Bering Strait
is 40–50 m (130–160 ft), therefore the land bridge opened when the sea level dropped more than 50 m (160 ft) below the current level. A reconstruction of the sea-level history of the region indicated that a seaway existed from c.   135,000 – c.  70,000 BP, a land bridge from c.  70,000 – c.  60,000 BP, intermittent connection from c.  60,000 – c.  30,000 BP, a land bridge from c.  30,000 – c.  11,000 BP, followed by a Holocene
Holocene
sea-level rise that reopened the strait. Post-glacial rebound has continued to raise some sections of coast.

During the last glacial period , enough of the earth's water became frozen in the great ice sheets covering North America
North America
and Europe
Europe
to cause a drop in sea levels . For thousands of years the sea floors of many interglacial shallow seas were exposed, including those of the Bering Strait
Bering Strait
, the Chukchi Sea
Chukchi Sea
to the north, and the Bering Sea
Bering Sea
to the south. Other land bridges around the world have emerged and disappeared in the same way. Around 14,000 years ago, mainland Australia
Australia
was linked to both New Guinea
New Guinea
and Tasmania
Tasmania
, the British Isles became an extension of continental Europe
Europe
via the dry beds of the English Channel
English Channel
and North Sea
North Sea
, and the dry basin of the South China
China
Sea linked Sumatra
Sumatra
, Java
Java
, and Borneo
Borneo
to Indochina
Indochina
.

BERINGIAN REFUGIUM

Beringia
Beringia
precipitation 22,000 years ago See also: Mammoth steppe and Asa_Gray § The "Asa Gray disjunction"

The last glacial period , commonly referred to as the "Ice Age", spanned 125,000 –14,500 YBP and was the most recent glacial period within the current ice age , which occurred during the last years of the Pleistocene
Pleistocene
era. The Ice Age reached its peak during the Last Glacial Maximum , when ice sheets began advancing from 33,000 YBP and reached their maximum limits 26,500 YBP. Deglaciation commenced in the Northern Hemisphere approximately 19,000 YBP and in Antarctica approximately 14,500 years YBP, which is consistent with evidence that glacial meltwater was the primary source for an abrupt rise in sea level 14,500 YBP and the bridge was finally inundated around 11,000 YBP. The fossil evidence from many continents points to the extinction of large animals, termed Pleistocene megafauna
Pleistocene megafauna
, near the end of the last glaciation.

During the Ice Age a vast, cold and dry Mammoth steppe stretched from the arctic islands southwards to China, and from Spain eastwards across Eurasia and over the Bering land bridge into Alaska
Alaska
and the Yukon
Yukon
where it was blocked by the Wisconsin glaciation
Wisconsin glaciation
. The land bridge existed because sea-levels were lower due to more of the planet's water being locked up in glaciers compared with today. Therefore, the flora and fauna of Beringia
Beringia
were more related to those of Eurasia rather than North America. Beringia
Beringia
received more moisture and intermittent maritime cloud cover from the north Pacific ocean than the rest of the Mammoth
Mammoth
steppe, including the dry environments on either side of it. This moisture supported a shrub-tundra habitat that provided a ecological refugium for plants and animals. In East Beringia
Beringia
35,000 YBP, the northern arctic areas experienced temperatures 1.5 C degrees warmer than today but the southern sub-Arctic regions were 2 C degrees cooler. During the LGM 22,000 YBP the average summer temperature was 3-5 C degrees cooler than today, with variations of 2.9 C degrees cooler on the Seward Peninsula
Seward Peninsula
to 7.5 C cooler in the Yukon. In the driest and coldest periods of the Late Pleistocene, and possibly during the entire Pleistocene, moisture occurred along a north-south gradient with the south receiving the most cloud cover and moisture due to the air-flow from the North Pacific.

In the Late Pleistocene, Beringia
Beringia
was a mosaic of biological communities. Commencing from c. 57,000 BP (MIS 3), steppe–tundra vegetation dominated large parts of Beringia
Beringia
with a rich diversity of grasses and herbs. There were patches of shrub tundra with isolated refugia of larch (Larix) and spruce (Picea) forests with birch (Betula) and alder (Alnus) trees. It has been proposed that the largest and most diverse megafaunal community residing in Beringia
Beringia
at this time could only have been sustained in a highly diverse and productive environment. Analysis at Chukotka on the Siberian edge of the land bridge indicated that from c. 57,000 – c. 15,000 BP (MIS 3 to MIS 2) the environment was wetter and colder than the steppe–tundra to the east and west, with warming in parts of Beringia
Beringia
from c. 15,000 BP. These changes provided the most likely explanation for mammal migrations after c. 15,000 BP, as the warming provided increased forage for browsers and mixed feeders. Beringia
Beringia
did not block the movement of most dry steppe-adapted large species such as saiga antelope, woolly mammoth, and caballid horses. However, from the west the woolly rhino went no further east than the Anadyr River, and from the east North American camels, the American kiang-like equids, the short-faced bear, bonnet-horned muskoxen, and badger did not travel west. At the beginning of the Holocene, some mesic habitat -adapted species left the refugium and spread westward into what had become tundra-vegetated northern Asia
Asia
and eastward into northern North America.

The latest emergence of the land bridge was c. 70,000 years ago. However, from c. 24,000 – c. 13,000 BP the Laurentide ice sheet fused with the Cordilleran ice sheet
Cordilleran ice sheet
, which blocked gene flow between Beringia
Beringia
(and Eurasia) and continental North America. The Yukon corridor opened between the receding ice sheets c. 13,000 BP, and this once again allowed gene flow between Eurasia and continental North America
North America
until the land bridge was finally closed by rising sea levels c. 10,000 BP. During the Holocene, many mesic-adapted species left the refugium and spread eastward and westward, while at the same time the forest-adapted species spread with the forests up from the south. The arid adapted species were reduced to minor habitats or became extinct.

Beringia
Beringia
constantly transformed its ecosystem as the changing climate affected the environment, determining which plants and animals were able to survive. The land mass could be a barrier as well as a bridge: during colder periods, glaciers advanced and precipitation levels dropped. During warmer intervals, clouds, rain and snow altered soils and drainage patterns. Fossil
Fossil
remains show that spruce , birch and poplar once grew beyond their northernmost range today, indicating that there were periods when the climate was warmer and wetter. The environmental conditions were not homogenous in Beringia. Recent stable isotope studies of woolly mammoth bone collagen demonstrate that western Beringia
Beringia
( Siberia
Siberia
) was colder and drier than eastern Beringia
Beringia
( Alaska
Alaska
and Yukon
Yukon
), which was more ecologically diverse. Mastodons , which depended on shrubs for food, were uncommon in the open dry tundra landscape characteristic of Beringia
Beringia
during the colder periods. In this tundra, mammoths flourished instead.

The extinct pine species Pinus matthewsii has been described from Pliocene sediments in the Yukon
Yukon
areas of the refugium.

The paleo-environment changed across time. Below is a gallery of some of the plants that inhabited eastern Beringia
Beringia
before the beginning of the Holocene
Holocene
.

* Gallery - plants of eastern Beringia
Beringia
( Alaska
Alaska
and the Yukon) c. 15,000 – c. 11,500 BP

*

Artemisia *

Cyperaceae (sedges ) *

Gramineae
Gramineae
(grasses ) *

Salix
Salix
(willow )

HUMAN HABITATION

Main articles: Settlement of the Americas
Settlement of the Americas
and Paleo-Indians
Paleo-Indians
Genetic settlement of Beringia
Beringia

The Bering land bridge is a postulated route of human migration to the Americas from Asia
Asia
about 20,000 years ago. An open corridor through the ice-covered North American Arctic was too barren to support human migrations before around 12,600 BP. A study has indicated that of the people who migrated across this land bridge at that time, only 70 left their genetic imprint on modern descendants, which is known as a founder effect (this is easily misread as implying that only 70 people crossed to North America).

Seagoing coastal settlers may also have crossed much earlier, but there is no scientific consensus on this point, and the coastal sites that would offer further information now lie submerged in up to a hundred metres of water offshore. Land animals migrated through Beringia
Beringia
as well, introducing to North America
North America
species that had evolved in Asia: mammals such as proboscideans and American lions , which evolved into now-extinct endemic North American species; and allowing equids and camelids that had evolved in North America
North America
(and later became extinct there) to migrate to Asia.

A study published in 2007 suggests that the Bering land bridge migration occurred 12,000 BP, that every human who migrated across the land bridge came from Eastern Siberia, and that every indigenous person directly descends from that same group of Eastern Siberian migrants. The authors note that a "nique genetic variant widespread in natives across both continents suggests that the first humans in the Americas came in a single migration or multiple waves from a single source, not in waves of migrations from different sources".

PREVIOUS CONNECTIONS

Biogeographical evidence demonstrates previous connections between North America
North America
and Asia. Similar dinosaur fossils occur both in Asia and in North America
North America
. For instance the dinosaur Saurolophus was found in both Mongolia and western North America. Relatives of Troodon , Triceratops
Triceratops
, and even Tyrannosaurus
Tyrannosaurus
rex all came from Asia.

Fossils in China
China
demonstrate a migration of Asian mammals into North America around 55 million years ago. By 20 million years ago, evidence in North America
North America
shows a further interchange of mammalian species. Some, like the ancient saber-toothed cats , have a recurring geographical range: Europe, Africa, Asia, and North America. The only way they could reach the New World
New World
was by the Bering land bridge. Had this bridge not existed at that time, the fauna of the world would be very different.

Researchers have started to use molecular phylogenetics to trace the history of faunal exchange and diversification, through the genetic history of parasites and pathogens of North American ungulates . An international Beringian Coevolution Project is collaborating to provide material to assess the pattern and timing of faunal exchange and the potential impact of past climatic events on differentiation.

SEE ALSO

* Bering Strait
Bering Strait
crossing * Bluefish Caves * Little John (archeological site)
Little John (archeological site)
* Geologic time scale
Geologic time scale
* Last glacial period
Last glacial period
* Pleistocene
Pleistocene
* Yukon
Yukon
Beringia
Beringia
Interpretive Centre

REFERENCES

* ^ A B Shared Beringian Heritage Program. "What is Beringia?". National Park Service, US Department of the Interior. * ^ Dr Barbara Winter (2005). "A Journey to a New Land". www.sfu.museum. virtualmuseum.ca. Retrieved 19 May 2015. * ^ John F. Hoffecker; Scott A. Elias (15 June 2007). Human Ecology of Beringia. Columbia University Press. p. 3. ISBN 978-0-231-13060-8 . Retrieved 2016-04-10. * ^ Karel Hendrik Voous (1973). Proceedings of the 15th International Ornithological Congress, The Hague, The Netherlands 30 August-5 September 1970. Brill Archive. p. 33. ISBN 978-90-04-03551-5 . Retrieved 2016-04-10. * ^ A B Wang, Sijia; Lewis, C. M. Jr.; Jakobsson, M.; Ramachandran, S.; Ray, N.; et al. (2007). "Genetic Variation and Population Structure in Native Americans" . PLoS Genetics . 3 (11): e185. PMC 2082466  . PMID 18039031 . doi :10.1371/journal.pgen.0030185 . * ^ Goebel, Ted; Waters, Michael R.; O'Rourke, Dennis H. (2008). "The Late Pleistocene Dispersal of Modern Humans in the Americas". Science . 319 (5869): 1497–1502. Bibcode :2008Sci...319.1497G. PMID 18339930 . doi :10.1126/science.1153569 . * ^ Fagundes, Nelson J. R.; et al. (2008). "Mitochondrial Population Genomics Supports a Single Pre-Clovis Origin with a Coastal Route for the Peopling of the Americas" . American Journal of Human Genetics . 82 (3): 583–592. PMC 2427228  . PMID 18313026 . doi :10.1016/j.ajhg.2007.11.013 . * ^ Tamm, Erika; et al. (2007). Carter, Dee, ed. "Beringian Standstill and Spread of Native American Founders" . PLoS ONE
PLoS ONE
. 2 (9): e829. Bibcode :2007PLoSO...2..829T. PMC 1952074  . PMID 17786201 . doi :10.1371/journal.pone.0000829 . * ^ Achilli, A.; et al. (2008). MacAulay, Vincent, ed. "The Phylogeny of the Four Pan-American MtDNA Haplogroups: Implications for Evolutionary and Disease Studies" . PLoS ONE. 3 (3): e1764. Bibcode :2008PLoSO...3.1764A. PMC 2258150  . PMID 18335039 . doi :10.1371/journal.pone.0001764 . * ^ Elias, Scott A.; Short, Susan K.; Nelson, C. Hans; Birks, Hilary H. (1996). "Life and times of the Bering land bridge". Nature . 382 (6586): 60. doi :10.1038/382060a0 . * ^ Jakobsson, Martin; Pearce, Christof; Cronin, Thomas M.; Backman, Jan; Anderson, Leif G.; Barrientos, Natalia; Björk, Göran; Coxall, Helen; De Boer, Agatha; Mayer, Larry A.; Mörth, Carl-Magnus; Nilsson, Johan; Rattray, Jayne E.; Stranne, Christian; Semilietov, Igor; oapos;regan, Matt (2017). "Post-glacial flooding of the Beringia Land Bridge dated to 11,000 cal yrs BP based on new geophysical and sediment records". Climate of the Past Discussions: 1. doi :10.5194/cp-2017-11 . CS1 maint: Multiple names: authors list (link ) * ^ Llanos, Miguel (21 September 2012). "Ancient land of \'Beringia\' gets protection from US, Russia". NBC News
NBC News
. Archived from the original on 23 September 2012. * ^ Hopkins DM. 1967. Introduction. In: Hopkins DM, editor. The Bering land bridge. Stanford: Stanford University Press. pp. 1–6. * ^ A B C Hoffecker, John F.; Elias, Scott A.; O'Rourke, Dennis H.; Scott, G. Richard; Bigelow, Nancy H. (2016). " Beringia
Beringia
and the global dispersal of modern humans". Evolutionary Anthropology: Issues, News, and Reviews. 25 (2): 64. doi :10.1002/evan.21478 . * ^ Hultén E. 1937. Outline of the history of arctic and boreal biota during the Quaternary Period. New York: Lehre J. Cramer. * ^ Nesom, G. L. (2011). "A New Species of Erythranthe (Phrymaceae) From China" (PDF). Phytoneuron. 7: 1–5. ISSN 2153-733X . * ^ Brubaker, Linda B.; Anderson, Patricia; Edwards, Mary E.; Anatoly, Lozhkin (2005). " Beringia
Beringia
as a glacial refugium for boreal trees and shrubs: New perspectives from mapped pollen data". Journal of Biogeography. 32 (5): 833–848. doi :10.1111/j.1365-2699.2004.01203.x . * ^

* Fagundes, Nelson J.R.; Kanitz, Ricardo; Eckert, Roberta; Valls, Ana C.S.; Bogo, Mauricio R.; Salzano, Francisco M.; Smith, David Glenn; Silva Jr., Wilson A.; et al. (3 March 2008). "Mitochondrial Population Genomics Supports a Single Pre-Clovis Origin with a Coastal Route for the Peopling of the Americas" (PDF). American Journal of Human Genetics . 82 (3): 583–592. PMC 2427228  . PMID 18313026 . doi :10.1016/j.ajhg.2007.11.013 . * Hoffecker, John F.; Elias, Scott A. (2007). Human ecology of Beringia. Columbia University Press. ISBN 978-0-231-13060-8 . Retrieved 2016-04-10. * Hoffecker, JF; Elias, SA; O'Rourke, DH (2014). "Anthropology. Out of Beringia?". Science . 343 (6174): 979–80. Bibcode :2014Sci...343..979H. PMID 24578571 . doi :10.1126/science.1250768 . * Hey, Jody (2005). "On the Number of New World
New World
Founders: A Population Genetic Portrait of the Peopling of the Americas" . PLoS Biology . 3 (6): e193. PMC 1131883  . PMID 15898833 . doi :10.1371/journal.pbio.0030193 . * Pielou, E. C. , After the Ice Age: The Return of Life to Glaciated North America
North America
(Chicago: University of Chicago Press) 1992 ISBN 978-0-226-66812-3 * Pringle, Heather (2014). "Welcome to Beringia". Science . 343 (6174): 961–3. PMID 24578560 . doi :10.1126/science.343.6174.961 .

EXTERNAL LINKS

Wikimedia Commons has media related to BERING LAND BRIDGE .

* Shared Beringian

.