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Thursday, July 5, 2018

Pleistocene Park

From Wikipedia, the free encyclopedia

Pleistocene Park
Плейстоценовый парк
Ice age fauna of northern Spain - Mauricio Antón.jpg
Depiction of some mammals common in northern Eurasia during the late Pleistocene, by Mauricio Antón. From left to right: wild horse, woolly mammoth, reindeer, cave lion and woolly rhinoceros.
Pleistocene Park is located in Russia
Pleistocene Park
Location Russian Arctic, Sakha Republic
Nearest city Chersky
Coordinates 68°30′48″N 161°31′32″ECoordinates: 68°30′48″N 161°31′32″E
Area 160 km2 (60 sq mi)
Established 1988 / 1996
Founder Sergey Zimov
Director Nikita Zimov
Website www.pleistocenepark.ru/en/

Pleistocene Park (Russian: Плейстоценовый парк) is a nature reserve on the Kolyma River south of Chersky in the Sakha Republic, Russia, in northeastern Siberia, where an attempt is being made to recreate the northern subarctic steppe grassland ecosystem that flourished in the area during the last glacial period.

The project is being led by Russian scientist Sergey Zimov,[3] with hopes to back the hypothesis that overhunting, and not climate change, was primarily responsible for the extinction of wildlife and the disappearance of the grasslands at the end of the Pleistocene epoch.[4][5]

A further aim is to research the climatic effects of the expected changes in the ecosystem. Here the hypothesis is that the change from tundra to grassland will result in a raised ratio of energy emission to energy absorption of the area, leading to less thawing of permafrost and thereby less emission of greenhouse gases.[4][5] It is also thought that removal of snow by large herbivores will further reduce the permafrost's insulation.

To study this, large herbivores have been released, and their effect on the local fauna is being monitored. Preliminary results point at the ecologically low-grade tundra biome being converted into a productive grassland biome, and at the energy emission of the area being raised.[6]

A documentary is being produced about the park by an American journalist and filmmaker.[7][8]

Goals

Researching the effects of large herbivores on the arctic tundra/grasslands ecosystem

The primary aim of Pleistocene Park is to recreate the mammoth steppe (ancient taiga/tundra grasslands that were widespread in the region during the last ice age). The key concept is that animals, rather than climate, maintained that ecosystem. Reintroducing large herbivores to Siberia would then initiate a positive feedback loop promoting the reestablishment of grassland ecosystems. This argument is the basis for rewilding Pleistocene Park's landscape with megafauna that were previously abundant in the area, as evidenced by the fossil record.[4][5][9]

The grassland-steppe ecosystem that dominated Siberia during the Pleistocene disappeared 10,000 years ago and was replaced by a mossy and forested tundra and taiga ecosystem.[4] Concurrently, most of the large herbivores that roamed Siberia during the Pleistocene have vanished from the region.[5] The mainstream explanation for this used to be that at the beginning of the Holocene the arid steppe climate changed into a humid one, and when the steppe vanished so did the steppe's animals.[4] Sergei Zimov points out that in contradiction to this scenario:
  • Similar climatic shifts occurred in previous interglacial periods without causing such massive environmental changes,[4][5][9]
  • Those large herbivores of the former steppe that survived until today (e.g. musk oxen, bison, horses) thrive in humid environments just as well as in arid ones,[4][5][9]
  • The climate (both temperatures and humidity) in today's northern Siberia is in fact similar to that of the mammoth steppe. The radiation aridity index for northern Siberia on Mikhail Budyko's scale is 2 (= steppe bordering on semi-desert).[4][5][9] Budyko's scale compares the ratio of the energy received by the earth's surface to the energy required for the evaporation of the total annual precipitation. The 'humid climate' argument was based on other scales, which compare precipitation to potential evapotranspiration. Moss has a very low transpiration rate and thus causes humidity without necessarily needing humidity for its establishment. Using these other scales as a proof for humidity being the cause of the disappearance of the grasslands therefore constitutes a circular argument, which is not scientifically viable.
Zimov and colleagues argue for a reversed order of environmental change in the mammoth steppe. Humans, with their constantly improving technology, overhunted the large herbivores and led to their extinction and extirpation.[4][5][9][10] Without herbivores grazing and trampling over the land, mosses, shrubs and trees were able to take over and replace the grassland ecosystem.[4][5][9][10] If the grasslands were destroyed because herbivore populations were decimated by human hunting, then "it stands to reason that those landscapes can be reconstituted by the judicious return of appropriate herbivore communities."[4]

Researching the effects of large herbivores on permafrost and global warming

A secondary aim is to research the climatic effects of the expected changes in the ecosystem. Here the key concept is that some of the effects of the large herbivores, such as eradicating trees and shrubs or trampling snow, will result in a stronger cooling of the ground in the winter, leading to less thawing of permafrost during summer and thereby less emission of greenhouse gases.

Permafrost is a large global carbon reservoir that has remained frozen throughout much of the Holocene.[12] Due to recent climate change, the permafrost is beginning to thaw, releasing stored carbon and forming thermokarst lakes.[12][13] When the thawed permafrost enters the thermokarst lakes, its carbon is converted into carbon dioxide and methane and released into the atmosphere. Methane is a potent greenhouse gas and the methane emissions from thermokarst lakes have the potential to initiate a positive feedback cycle in which increased atmospheric methane concentrations lead to amplified global climate change, which in turn leads to more permafrost thaw and more methane and carbon dioxide emissions.[15][16]

As the combined carbon stored in the world's permafrost (1670 Gt)[17] equals about two times the amount of the carbon currently released in the atmosphere (720 Gt),[18] the setting in motion of such a positive feedback cycle could potentially lead to runaway climate change scenario. Even if the ecological situation of the arctic were as it was 400,000 years ago (i.e., grasslands instead of tundra), a global temperature rise of 1.5 °C (2.7 °F) relative to the pre-industrial level would be enough to start the thawing of permafrost in Siberia.[19] An increased cooling of the ground during winter would raise the current tipping point, potentially delaying such a scenario.

Implementation

Background: regional Pleistocene ecoregions

It has been proposed that the introduction of a variety of large herbivores will recreate their ancient ecological niches in Siberia and regenerate the Pleistocene terrain with its different ecological habitats such as taiga, tundra, steppe and alpine terrain.

The main object, however, is to recreate the extensive grasslands that covered the Beringia region in the late Pleistocene. This form of grassland (also known as mammoth steppe) was inhabited by a diverse set of large and medium herbivores. Back in the Pleistocene the area was populated by many species of grazers that assembled in large herds similar in size to those in Africa today. Species that roamed the great grasslands included the woolly mammoth, woolly rhino, steppe wisent, Lena horse, muskox, and reindeer.

Another herbivore that was abundant in this region during the Pleistocene but now faces possible extinction in its remaining habitats is the saiga antelope, which can form massive herds that keep the vegetation down.

At the edges of these large stretches of grassland could be found more shrub-like terrain and dry conifer forests (similar to taiga). In this terrain the browsers of the Pleistocene were to be found. This group of megafauna included woolly rhinoceros, moose, wapiti, Yukon wild ass, and camels. The more mountainous terrain was occupied by several species of mountain-going animals like the snow sheep.

Back in the Pleistocene there was also a great variety of carnivorous mammals as well. On the plains there were prides of Beringian cave lion. These large cats were the apex predators of the region, but also shared their habitat with other predators such as grey wolf, cave hyena, Homotherium, brown bear, wolverine, and Arctic fox, which all occupied a distinct ecological niche essential for the balance of their respective ecosystems.

On the edges of the grasslands (in the shrubs and forests) there were also brown bears, wolverines, cave bears, lynxes, tigers, leopards, and red foxes. The Siberian tiger and Amur leopard occupied the southern part of the steppe biome and surviving populations are still found along the present Russian-Sino border in the Amur and Primorye regions.

Proposed procedure

In present-day Siberia only a few of the former species of megafauna are left, and their population density is extremely low, too low to affect the environment. To reach the desired effects, the density has to be raised artificially by fencing in and concentrating the existing large herbivores. A large variety of species is important as each species affects the environment differently and as the overall stability of the ecosystem increases with the variety of species[4] (compare Biodiversity#Biodiversity and ecological services). Their numbers will be raised by reintroducing species that went locally extinct (e.g., muskoxen). For species that went completely extinct, suitable replacements will be introduced if possible (e.g., wild Bactrian camels for the extinct Pleistocene camels of the genus Paracamelus). As the number of herbivores increases, the enclosure will be expanded.

While this is taking place, the effects will be monitored. This concerns for example the effects on the flora (are the mosses being replaced by grasses, etc.), the effects on the atmosphere (changes in levels of methane, carbon dioxide, water vapor) and the effects on the permafrost.

Finally, once a high density of herbivores over a vast area has been reached, predators larger than the wolves will have to be introduced to keep the megafauna in check.[4][5]

Progress and plans

1988–1996
The first grazing experiments began in 1988 at the Northeast Science Station in Chersky with Yakutian horses.[6]
1996–2004
In 1996 a 50 ha (125 acre) enclosure was built in Pleistocene Park.[5] As a first step in recreating the ancient landscape, the Yakutian horses were introduced, as horses had been the most abundant ungulates on the northeastern Siberian mammoth steppe.[24] Of the first 40 horses, 15 were killed by predators and 12 died of eating poisonous plants. More horses were imported, and they learned to cope with the environment.[22] In 2006 approximately 20 horses lived in the park,[25] and by 2007 more horses were being born annually than died.[22] By 2013, the number had risen to about 30.[26] Moose, present in the area, were also introduced.[27] The effects of large animals (mammoths and wisents) on nature were artificially created by using an engineering tank and an 8-wheel drive Argo all-terrain vehicle to crush pathways through the willow shrub.

Restored grasslands in Pleistocene Park

The vegetation in the park started to change. In the areas where the horses grazed, the soil has been compacted[23] and mosses, weeds and willow shrub were replaced by grasses.[3][6][21][31] Flat grassland is now the dominating landscape inside the park.[30] The permafrost was also influenced by the grazers. When air temperature sank to –40 °C (–40 °F) in winter, the temperature of the ground was found to be only –5 °C (+23 °F) under an intact cover of snow, but –30 °C (–22 °F) where the animals had trampled down the snow. The grazers thus help keep permafrost intact, thereby lessening the amount of methane released by the tundra.[6][9]
2004–2011
In the years 2004–2005 a new fence was erected, creating an enclosure of 16 km2 (6 sq mi).
The new enclosure finally allowed a more rapid development of the project.[21] After the fence was completed, reindeer were brought into the park from herds in the region and are now the most numerous ungulates in the park.[27][33] To increase moose density in the park, special constructions were added to the fence in several places that allow animals outside the fenced area to enter the park, while not allowing them to leave. Besides that, wild moose calves were caught in other regions and transported to the park.[34]

In 2007 a 32-meter (105-foot) high tower was erected in the park that constantly monitors the levels of methane, carbon dioxide and water vapor in the park's atmosphere.[22][35]

In September 2010 the muskox was reintroduced. Six male animals were imported from Wrangel Island,[36] two of which died in the first months.[22][37] Seven months later, in April 2011, six Altai wapitis and five wisents arrived at the park, the wapitis originating from the Altai mountains and the wisents from Prioksko-Terrasny Nature Reserve near Moscow.[38][39] But the enclosing fence proved too low for the wapitis, and by the end of 2012 all six wapitis had jumped the fence and run off.[11]
2011–2016
In the years 2011 to 2016 progress slowed down as most energy was put into the construction of a 150 ha (370 ac) branch of Pleistocene Park near the city of Tula in Tula Oblast in Europe,[26][40] see below (Wild Field section). A few more reindeer and moose were introduced into Pleistocene Park during this time,[40][41] and a monitoring system for measuring the energy balance (ratio of energy emission and energy absorption)[note 1] of the pasture was installed.[42][43]
2017–
Attention has now been shifted back to the further development of Pleistocene Park. A successful crowdfunding effort in early 2017 provided funding for further animal acquisitions.[44][45][46] Later that year twelve domestic yak[47][48] and 30 domestic sheep[49][50] were brought to the park. The introduction of a herd of 12 plains bison is planned for May 2018,[51][52] and the introduction of more muskoxen is planned for 2019.[53]

For the near future the focus in animal introductions will generally be placed on browsers, not grazers, i.e., bison, muskoxen, moose and wapiti. Their role in this phase will be to diminish the amount of shrubs and trees and enlarge the grassy areas. Only when these areas have sufficiently increased will grazers like saiga and kiang be introduced.[54][55]

Reception

Controversial aspects

Critics admonish that introducing alien species could damage the fragile ecosystem of the existing tundra. To this criticism Sergey Zimov replied: ″Tundra – that is not an ecosystem. Such systems had not existed on the planet [before the disappearance of the megafauna], and there is nothing to cherish in the tundra. Of course, it would be silly to create a desert instead of the tundra, but if the same site would evolve into a steppe, then it certainly would improve the environment. If deer, foxes, bovines were more abundant, nature would only benefit from this. And people too. However, the danger still exists, of course, you have to be very careful. If it is a revival of the steppes, then, for example, small animals are really dangerous to release without control. As for large herbivores – no danger, as they are very easy to remove again.″[56]

Another point of concern is doubt that the majority of species can be introduced in such harsh conditions. For example, according to some critics, the Yakutian horses, although they have been living in the park for several generations, would not have survived without human intervention. They normally tolerate –60 °C, but are said to cope poorly with an abundance of snow and possibly would have died within the first snowy winter of starvation. However, horses of much less primitive stock abandoned by the Japanese Army have been living feral on some uninhabited Kuril Islands since 1945. Despite the deep snows (two to three times deeper than in Yakutia), they have successfully survived all the winters without feeding. And in Pleistocene Park, while some of the Yakutian horses accept supplementary feeding, others keep away and survive on their own.[22]

Positive reception

The Zimov’s concept of Pleistocene Park and repopulating the mammoth steppe is listed as one of the “100 most substantive solutions to global warming” by Project Drawdown.[57] The list, encompassing only technologically viable, existing solutions, was compiled by a team of over 200 scholars, scientists, policymakers, business leaders and activists;[58][59] for each solution the carbon impact through the year 2050, the total and net cost to society, and the total lifetime savings were measured and modelled.[60][61]

Visitors

The park is a hub for international scientists and students, who come from around the world to conduct their own ecological research and experiments.[6] The Polaris Project was a yearly visitor from 2009 to 2015, sending US-American students on excursions to the park each summer.[62]

Another group of visitors are journalists. The park is steadily gaining more media attention and while most journalists do not come to the park itself the number of visitors is increasing. In 2016 for example, the park was visited by a filmmaker, two print media (Swiss 24 Heures and American The Atlantic), and two TV broadcasting companies (German ARD and American HBO).[63]

The total of visitors for 2016 (summer months only) was 45.[64]

Size and administration

Pleistocene Park is a 160 km2 scientific nature reserve (zakaznik) consisting of willow brush, grasslands, swamps, forests and a multitude of lakes.[4][65][note 2] The average temperature in January is about –33 °C and in July +12 °C; annual precipitation is 200–250 mm.[5]

Pleistocene Park is owned and administered by a non-profit corporation, the Pleistocene Park Association, consisting of the ecologists from the Northeast Science Station in Chersky and the Grassland Institute in Yakutsk.[65] The present park area was signed over to the association by the state and is exempt from land tax.[66] The reserve is surrounded by a 600 km2 buffer zone that will be added to the park by the regional government once the animals have successfully established themselves.[65]

In July 2015 the Pleistocene Park Foundation was founded, a non-profit organization (registered in Pennsylvania, USA, with 501(c)(3) status)[67] dedicated to acquiring private donations for funding Pleistocene Park.[68] Hitherto Pleistocene Park had been financed solely through the funds of the founders, a practice that grew increasingly insufficient.[68]

Animals

Animals already present in the park:

Herbivores:

Yakutian horses
  • Reindeer (Rangifer tarandus):[33] Present before the project started (although more are being brought to help simulate Pleistocene conditions). They mainly graze in the southern highlands of the park. This territory is not affected by spring flooding and dominated by larch forests and shrubland. Reindeer rarely visit the flood plain. Besides actively grazing (especially in winter) they browse on willow shrubs, tree moss, and lichens. (Numbers in park in July 2017: approximately 20)[69]
  • Elk[BE]/moose[AE] (Alces alces):[34] Present before the project started, although in low numbers. Immigration from neighboring areas is stimulated. Due to poaching the density of moose in the region has substantially decreased in the last 20 years. To increase moose density in the park, special constructions were added to the fence in several places that allow animals outside the fenced area to enter the park, while not allowing them to leave. Besides that wild moose calves are being caught in other regions and transported to the park.[34] It is the largest extant species of the deer family and one of the largest herbivores in the park today. (Numbers in park in July 2017: approximately 15)[69]
  • Yakutian horse (a domestic breed of Equus ferus caballus):[70] The first species to be introduced for the project, they were imported from the surrounding Srednekolymsk region beginning in 1988.[70] Yakutian horses have developed a range of remarkable morphologic, metabolic and physiologic adaptions to the harsh environment of Siberia, including an extremely dense and long winter coat, a compact build, a metabolism adjusted to seasonal needs, and an increased production of antifreezing compounds.[71][72] In summer they grow very large hooves, which they wear down in winter scraping away snow to get at food. Despite their size, they proved to be dominant over the wisents, who often fled from them. Yakutian horses are purely grazing animals – they eat only grass species, and visit the park's forests only during the spring flood. In the spring of 2015, ten more Yakutian horses were acquired to increase genetic diversity.[73] (Numbers in park in May 2018: approximately 30)[66]
Muskoxen family
  • Muskox (Ovibos moschatus):[74] Muskoxen arrived at the park in September 2010. They were brought from Wrangel Island[74] (itself repopulated with animals from North America). They are doing well and are now fully grown. Unfortunately only males could be acquired, and the Zimovs are now urgently looking for females.[37] The introduction of more muskoxen is planned for 2019.[53] (Numbers in park in July 2017: 3 males)[69]
  • Wisent (European bison, Bison bonasus):[75] During the last ice age, wisents were the most cold-adapted of the Bison species and thrived in the glacial grassland-steppe biome.[76][note 3] Their dietary needs are very different from the American bison. Year-round 10% of their intake necessarily consists of trees and shrubs, and they will ignore their main forage (grasses, sedges and forbs) in favour of woody forage to reach this quota.[77] Without supplementary feeding in winter, the yearly average may rise to 20% even in countries with mild winters.[78] Five wisents, one adult male and four juvenile females, were introduced in the park in April 2011. The wisents were brought to the park from the Prioksko-Terrasny Nature Reserve near Moscow.[39][75] The transportation was more complicated and took a longer time than originally thought, but all the animals recovered rapidly after the trip. Unfortunately, the wisents did not sufficiently acclimatize in the first months. They started to moult in November, when temperatures already were down to –30 °C (–35 °F) in Cherskii. The four juveniles died; only the adult bull survived. He is now fully acclimatized.[26][79] (Numbers in park in July 2017: 1 male)[69]
Domestic yak in the Altai Mountains
Carnivores:
Eurasian brown bear
Animals considered for reintroduction:

Herbivores:
  • American bison (Bison bison):
  • Altai wapiti or Altai maral (Cervus canadensis sibiricus): Had been introduced in April 2011.[102] The wapiti made their way to the park all the way from the mountainous regions of Altai in central southern Siberia.[102] Wapiti are very good jumpers and all six escaped within the first two years. The fence has been strengthened to cope with future introductions.[11][41]
Altai maral
  • Wild yak (Bos mutus): Could be brought from the Tibetan Plateau. Along with the bison, horse, and reindeer, the species could contribute to the further proliferation of grasses in the region.[11][103]
  • Snow sheep (Ovis nivicola): Immigration from neighboring areas is encouraged. Especially rams may be lured to the park by domestic ewes in rut.[citation needed]
  • Saiga antelope (Saiga tatarica): Introduction is in the planning stage. Its presence would be critical for the regulation of poisonous plants in the region that can be digested by the saiga but are harmful to other herbivores. Currently, free saigas can only be found in Russia in the Chyornye Zemli Nature Reserve.
  • Wild Bactrian camel (Camelus ferus) or Bactrian camel (Camelus bactrianus): Either of the two-humped camel species could act as a proxy for extinct Pleistocene camel species, whose fossils have been found in areas that once formed part of Beringia.[103] The camel evolved in the high arctic as a large boreal browser; its hump presumably evolved to store fat as a resource for the long winter.[82] Bactrian camels will eat almost anything, preferably any plant material such as grass, shrubs, bark, etc., but in times of need also carrion.[104][105] In the winter they will dig under snow to get at forage.[104] The wild Bactrian camel is critically endangered and is only found in some few areas of China and Mongolia.
  • Siberian roe deer (Capreolus pygargus): Immigration from neighboring areas is encouraged.
Carnivores:

Siberian tiger
  • Siberian tiger (Panthera tigris altaica): Introduction planned for a later stage, when herbivores have multiplied.[4][5][22] Endangered and reduced to the Primorye region. As the largest feline alive, the Siberian tiger could play a key role in regulating the numbers of the largest herbivores.
Animals that could be placed in the park in the event of being 'resurrected' from extinction:

Woolly mammoth model at the Royal BC Museum, Victoria, British Columbia
  • Woolly mammoth (Mammuthus primigenius): In January 2011, the Yomiuri Shimbun reported that a team of scientists from Kyoto University were planning to extract DNA from a mammoth carcass preserved in a Russian laboratory and insert it into egg cells of elephants in hope of creating a mammoth embryo. If the experiment succeeded, the calf would be taken to the park along with others to form a wild population. The researchers claimed that their aim was to produce the first mammoth within six years.[103][106][107][108][109]

Southern branch of Pleistocene Park: The Wild Field wilderness reserve

In 2012 to 2014 a branch of Pleistocene Park named ″Wild Field″ (Russian: Дикое поле Dikoe pole) was constructed near the city of Tula in Tula Oblast in the European part of Russia, approximately 250 km (150 mi) south of Moscow.[26][110]
Unlike Pleistocene Park, Wild Field's primary purpose is not scientific research but public outreach, i.e., it will provide a model of what an unregulated steppe ecosystem looked like before the advent of humans. It is situated near a federal road and a railway station and will be accessible to the general public.[110]

Wild Field comprises 300 ha (740 ac)[110] of which 280 ha have been fenced off and stocked with animals.[111] Already present in the park are nine species of large herbivores and one omnivore species: Bashkir horses (a strain of Equus ferus caballus) from the southern part of the Ural Mountains,[112][113] Altai maral/Altai wapiti (Cervus canadensis sibiricus),[113] Edilbaevskaya sheep (a strain of Ovis orientalis aries),[114] roe deer (Capreolus spec.),[note 5][110][116] Kalmykian cattle (a strain of Bos primigenius taurus),[117][118] domestic yaks (Bos mutus grunniens),[117][118][119] wild boar (Sus scrofa),[119] one female elk[BE]/moose[AE] (Alces alces),[119] four reindeer (Rangifer tarandus)[120] and 73 domestic Pridonskaya goats (a strain of Capra aegagrus hircus).
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Scientists create embryos, hope to save near-extinct rhino

 
AFP / TONY KARUMBA
 
Original link:  https://www.afp.com/en/news/205/scientists-create-embryos-hope-save-near-extinct-rhino-doc-1759ps2
 
Najin (L) and Fatu are the only two northern white rhino known to be alive today - both are infertile females

Scientists create embryos, hope to save near-extinct rhino Months after the death of Sudan, the world's last male northern white rhino, scientists said Wednesday they have grown embryos containing DNA of his kind, hoping to save the subspecies from extinction.

With only two northern white rhino (NWR) known to be alive today -- both infertile females -- the team hopes their breakthrough technique will lead to the re-establishment of a viable NWR breeding population.

"Our goal is to have in three years the first NWR calf born," Thomas Hildebrandt, head of reproduction management at the Leibniz Institute for Zoo and Wildlife Research in Berlin, told journalists of the work.

"Taking into account 16 months (of) pregnancy, we have a little more than a year to have a successful implantation."

The team's work, using a recently-patented, two-metre (6.6-foot) egg extraction device, resulted in the first-ever test tube-produced rhino embryos.

Now frozen, these "have a very high chance to establish a pregnancy once implanted into a surrogate mother," said Hildebrandt.

The hybrid embryos were created with frozen sperm from dead NWR males and the eggs of southern white rhino (SWR) females, of which there are thousands left on Earth.

The eggs were harvested from rhinos in European zoos.

The team now hopes to use the technique to collect eggs from the last two northern white rhinos -- Najin and Fatu, the daughter and granddaughter of Sudan. They live in a Kenyan national park.

- Risk and reward -

By fertilising these with northern white rhino sperm and implanting the resulting embryos in surrogate southern white rhino females, the team intends to create a new, fledgling NWR population.

"Our results indicate that ART (assisted reproduction techniques) could be a viable strategy to rescue genes from the iconic, almost extinct, northern white rhinoceros," the team wrote in the journal Nature Communications.

The researchers have sought permission to harvest eggs from Najin and Fatu in Kenya, hopefully before the end of the year.

But the procedure is not without risk: "we have to do a full anaesthesia, the animal is down for two hours, and it is quite a risky situation" for the last two of their kind, conceded Hildebrandt.

"We are highly afraid something unexpected would happen, that would be a nightmare."

In the meantime, the team will practice, implanting some of their hybrid embryos into SWR surrogates "to test the system".

Any hybrids born as a result may play a crucial future role as surrogates, sharing more genes with northern rhinos than purely southern surrogates.

There is, however, a key obstacle to the team's envisaged NWR repopulation.

With only two NWR females left and all the available semen from only four dead males, ART alone would likely lead to a population without the genetic diversity required for a species to thrive.

- Can it work? -

To this end, the researchers hope to use stem cell technology to engineer eggs and sperm from the frozen skin cells of 12 dead northern white rhinos, unrelated to one another.

"This would enlarge the founding diversity of the future NWR population substantially," the team said in a statement.

There is time pressure, they pointed out, with only two animals still around to socialise the babies in the mysterious ways of northern white rhinos.

"It is a motivating aspect to succeed as soon a possible so the calf that we produce can grow up with Najin and Fatu," said Hildebrandt.

Terri Roth and William Swanson of the Cincinnati Zoo and Botanical Garden, in a comment on the study, said ART alone cannot save a species from extinction.

"Impressive results in a Petri dish don't easily translate into a herd of healthy offspring," wrote the duo, not involved in the research.

"Achieving the latter requires navigating an untrodden path fraught with obstacles, and it remains unlikely that a viable population of northern white rhinos will be restored."

For the researchers, however, a combination of ART and stem cell techniques, could "provide a blueprint on how to save highly endangered species that have already dwindled to numbers that make conventional conservation efforts impossible."
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Pleistocene rewilding

From Wikipedia, the free encyclopedia
Pleistocene rewilding is the advocacy of the reintroduction of descendants of Pleistocene megafauna, or their close ecological equivalents. An extension of the conservation practice of rewilding, which involves reintroducing species to areas where they became extinct in recent history (hundreds of years ago or less).

Towards the end of the Pleistocene era (roughly 13,000 to 10,000 years ago), nearly all megafauna of Eurasia, Australia, and South/North America, dwindled towards extinction, in what has been referred to as the Quaternary extinction event. With the loss of large herbivores and predator species, niches important for ecosystem functioning were left unoccupied.[2] In the words of the biologist Tim Flannery, "ever since the extinction of the megafauna 13,000 years ago, the continent has had a seriously unbalanced fauna". This means, for example, that the managers of national parks in North America have to resort to culling to keep the population of ungulates under control.[3]

Paul S. Martin (originator of the Pleistocene overkill hypothesis[4]) states that present ecological communities in North America do not function appropriately in the absence of megafauna, because much of the native flora and fauna evolved under the influence of large mammals.[5]

Ecological and evolutionary implications

Research shows that species interactions play a pivotal role in conservation efforts. Communities where species evolved in response to Pleistocene megafauna (but now lack large mammals) may be in danger of collapse.[6][7] Most living megafauna are threatened or endangered; extant megafauna have a significant impact on the communities they occupy, which supports the idea that communities evolved in response to large mammals. Pleistocene rewilding could "serve as additional refugia to help preserve that evolutionary potential" of megafauna.[7] Reintroducing megafauna to North America could preserve current megafauna, while filling ecological niches that have been vacant since the Pleistocene.[8]

Possible fauna for reintroduction (North America)


The Bolson tortoise, the first proposed candidate for Pleistocene rewilding

Pleistocene rewilding aims at the promotion of extant fauna and the reintroduction of extinct genera in the southwestern and central United States. Native fauna are the first genera proposed for reintroduction. The Bolson tortoise was widespread during the Pleistocene era, and continued to be common during the Holocene epoch until recent times. Its reintroduction from northern Mexico would be a necessary step to recreate the soil humidity present in the Pleistocene, which would support grassland and extant shrub-land and provide the habitat required for the herbivores set for reintroduction. Other large tortoise species might later be introduced to fill the roll of various species of Hesperotestudo. However, to be successful, ecologists must first support fauna already present in the region.

The pronghorn, which is extant in most of the west after almost becoming extinct, is crucial to the revival of the ancient ecosystem. Pronghorns are native to the region, which once supported large numbers of the species and extinct relatives of the same family. It would occupy the great plains and other arid regions of the west and southwest.

The plains bison numbered in the millions during the Pleistocene era, until European settlers drove them to near-extinction in the late 19th century. The bison has made a recovery in many regions of its former range, and is involved in several local rewilding projects across the Midwestern United States.

Bighorn sheep and mountain goats are already present in the surrounding mountainous areas and therefore should not pose a problem in rewilding more mountainous areas. Mountain goats are already being introduced to areas formerly occupied by Oreamnos haringtoni, a more southern relative that went extinct at the end of the Pleistocene. Reintroducing extant species of deer to the more forested areas of the region would be beneficial for the ecosystems they occupy, providing rich nutrients for the forested regions and helping to maintain them. These species include elk, white-tailed and mule deer.

Herbivorous species considered beneficial for the regional ecosystems include the collared peccary, a species of New World wild pig that was abundant in the Pleistocene. Although this species (along with the flat-headed and long-nosed peccaries) are extinct in many regions of North America, their relatives survive in Central and South America and the collared peccary can still be found in southern Arizona and Texas. The Chacoan peccary, which is morphologically very similar to the flat-headed peccary, might be able to replace it in areas of the Great Plains and the South.

Horses originated in North America and spread to Asia via the Ice Age land bridge, but became extinct in their evolutionary homeland alongside the mammoth and ground sloth. The Pleistocene grasslands of North America were the birthplace of the modern horse, and by extension the wild horse. Przewalski's horses are well adapted to arid and grassland regions and could be introduced as a substitute for their close North American relative, Scott's horse. The stilt-legged horses might be approximated by the morphologically similar onagers, kiangs, and asses. Animals that would serve as predators of these equine species would include lions and wolves[9].

Alongside the wild horse, camels evolved in the drier regions of North America. Proof of this can be seen in the camelids of South America: the llama, alpaca, guanaco and vicuna. North America links the South American camelids with those of the Old World (the dromedary and Bactrian camel). Pleistocene rewilding suggests that the closest relatives of the North American species of camelid be reintroduced. The best candidates would be the wild Bactrian as a proxy for Camelops, the guanaco as a proxy for Hemiauchenia, and possibly the Vicuna as a proxy for Palaeolama. These species would live in the arid regions and grasslands of North America. Free-ranging camels face predators typical of their regional distribution, which include wolves and lions[10]. The main predator of guanacos and vicunas is the cougar[11].


The mountain tapir

During the Pleistocene, a species of tapir existed in North America with many regional variants. They became extinct at the end of the Pleistocene era, but their relatives survive in Asia and South America. The mountain tapir would be an excellent choice for rewilding humid areas, such as those near lakes and rivers. The mountain tapir is the only extant non-tropical species of tapir. Predators of mountain tapirs include cougars, bears, and, less commonly, jaguars.[12] Good introduction areas might include forested ecosystems of the west and east coasts, and the more scrub-like or wetland ecosystem of the south.

During the Pleistocene, large populations of Proboscideans lived in North America, such as the Columbian mammoth and the American mastodon. The mastodons all became extinct at the end of the Pleistocene era, as did the mammoths of North America. However, an extant relative of the mammoth is the Asian elephant. It now resides only in tropical southeastern Asia, but the fossil record shows that it was much more widespread, living in temperate northern China as well as the Middle East (an area bearing an ecological similarity to the southern and central United States). The Asian elephant is possibly a good candidate for Pleistocene rewilding in North America. Asian elephants would do well in the environments previously occupied by the Columbian mammoth.

Pleistocene America boasted a wide variety of dangerous carnivores (most of which are extinct today), such as the short-faced bear, saber-toothed cats (e.g. Homotherium), the American lion, dire wolf, American cheetah and (possibly) the terror bird. Some carnivores and omnivores survived the end of the Pleistocene era and were widespread in North America until Europeans arrived, such as grizzly bears, cougars, jaguars, grey and red wolves, bobcats, and coyotes.[13] The cheetah could serve as a substitute for Miracinonyx, keeping the population of pronghorns in check. Jaguars could be reintroduced back to areas of North America to control populations of prey animals. Some of the larger cats such as the African lion could act as a proxy for the Pleistocene American lion, they could be introduced to keep the numbers of American bison, equids, and camelids in check.

Criticism

The main criticism of the Pleistocene rewilding is that it is unrealistic to assume that communities today are functionally similar to their state 10,000 years ago. Opponents argue that there has been more than enough time for communities to evolve in the absence of mega-fauna, and thus the reintroduction of large mammals could thwart ecosystem dynamics and possibly cause collapse. Under this argument, the prospective taxa for reintroduction are considered exotic and could potentially harm natives of North America through invasion, disease, or other factors.[1]

Opponents of the Pleistocene rewilding present an alternative conservation program, in which more recent North American natives will be reintroduced into parts of their native ranges where they became extinct during historical times.[1] Another way of rewilding Americas, Asia, etc. is by using de-extinction, bringing extinct species back to life through cloning.[14]

Pleistocene rewilding in Europe

This plan was considered by Josh Donlan and Jens-C. Svenning, and involves (as in rewilding North America) creating a Pleistocene habitat in portions of Europe.[12] Svenning claims that "Pleistocene Rewilding can be taken for consideration outside of North America". Incidentally, an independent "Rewilding Europe" initiative was established in the Netherlands in 2011, with the western Iberian Peninsula, Velebit, the Danube delta and the eastern and southern Carpathians as particular targets.[13]

The proxies which may be used for this project(s) are:

Animals which have been already introduced


European Bison

Expanding populations

Northern Siberia

The aim of Siberian Pleistocene rewilding is to recreate the ancient mammoth steppe by reintroducing megafauna. The first step was the successful reintroduction of musk oxen on the Taymyr Peninsula and Wrangel island. In 1988, researcher Sergey Zimov created Pleistocene Park – a nature reserve in northeastern Siberia for full-scale megafauna rewilding.[15] Reindeer, Siberian roe deer and moose were already present; Yakutian horses, muskox, Altai wapiti and wisent were reintroduced. Reintroduction is also planned for yak, Bactrian camels, snow sheep, Saiga antelope, and Siberian tigers. The wood bison, closest relative of the ancient bison which became extinct in Siberia 1,000 to 2,000 years ago, is an important species for the ecology of Siberia. In 2006, 30 bison calves were flown from Edmonton, Alberta to Yakutsk. Now they live in the government-run reserve of Ust'-Buotama.


Woolly mammoth

Animals which have been already introduced Fallow deer, reintroduced from Anatolia in most parts of Europe already in Ancient times. Mouflon, reintroduced for hunting purposes in the continent from the island populations of Corsica and Sardinia (originated in turn by introductions from the Middle East during the Neolithic period). Musk ox, reintroduced in 1976 to Russia (Taimyr Peninsula and Wrangel Island) and Scandinavia.[14] Northern bald ibis, extinct in southern Europe during the Modern Age, has reintroduction projects underway in Austria and Spain. European bison, saved from extinction in zoos in the early 20th century and reintroduced in several places of Eastern Europe. American bison in Askania Nova, Ukraine, a proxy for the Pleistocene steppe bison. Expanding populations Wisent Alpine ibex Spanish ibex Chamois Moose Wolf Eurasian lynx Iberian lynx Brown bear European mink Mediterranean monk seal European beaver Osprey White-tailed eagle Griffon vulture Eurasian black vulture Eurasian eagle owl.

Animals that have been already introduced

  • Musk ox (became extinct in Siberia about 2000 years ago, but has been reintroduced in Taimyr Peninsula and on Wrangel Island)[16]
  • Wood bison (A group of thirty wood bison were introduced to Yakutia in 2006 as a proxy for the extinct steppe bison)[17]
  • Yakutian horse (A group of these horses were brought to Pleistocene Park to replace the extinct horses)
  • Domestic Yak Six domestic yak were brought to Pleistocene Park in 2017. It turned out that two of the Yaks were pregnant so now there are eight Yak in Pleistocene Park.

Considered for reintroduction

Island landmasses

Megafauna that arose on insular landmasses were especially vulnerable to human influence because they evolved in isolation from other landmasses, and thus were not subjected to the same selection pressures that surviving fauna were subject to, and many forms of insular megafauna were wiped out after the arrival of humans. Therefore, scientists have suggested introducing closely related taxa to replace the extinct taxa. This is being done on several islands, with replacing closely related or ecologically functional giant tortoises to replace extinct giant tortoises.[19] For example, the Aldabra giant tortoise has been suggested for replacing the extinct Malagasy giant tortoises,[20][21] and Malagasy radiated tortoises have been introduced to Maritius to replace the tortoises that were present there.[22] However, the usage of tortoises in rewilding experiments have not been limited to replacing extinct tortoises. At the Makauwahi Cave Reserve in Hawaii, exotic tortoises are being used as a replacement for the extinct moa-nalo,[23] a large flightless duck hunted to extinction by the first Polynesians to reach Hawaii. The grazing habits of these tortoises control and reduce the spread of invasive plants, and promote the growth of native flora.[24]

Australia

Expanding populations
Extant outside Australia
at

Societal collapse

From Wikipedia, the free encyclopedia

Societal collapse is the fall of a complex human society. Such a disintegration may be relatively abrupt, as in the case of Maya civilization, or gradual, as in the case of the fall of the Western Roman Empire.

The subject of societal collapse is of interest in such fields as history, anthropology, sociology, political science, and, more recently, complex-systems science.

Causes of collapse

Common factors that may contribute to societal collapse are economical, environmental, social and cultural, and disruptions in one domain sometimes cascade into others. In some cases a natural disaster (e.g. tsunami, earthquake, massive fire or climate change) may precipitate a collapse. Other factors such as a Malthusian catastrophe, overpopulation or resource depletion might be the proximate cause of collapse. Significant inequity may combine with lack of loyalty to established political institutions and result in an oppressed lower class rising up and seizing power from a smaller wealthy elite in a revolution. The diversity of forms that societies evolve corresponds to diversity in their failures. Jared Diamond suggests that societies have also collapsed through deforestation, loss of soil fertility, restrictions of trade and/or rising endemic violence.[1]

Foreign invasions

The decline of the Roman Empire is one of the events traditionally marking the end of Classical Antiquity and the beginning of the European Middle Ages. Throughout the 5th century, the Empire's territories in western Europe and northwestern Africa, including Italy, fell to various invading or indigenous peoples in what is sometimes called the Barbarian invasions, although the eastern half still survived with borders essentially intact for another two centuries (until the Arab expansion). This view of the collapse of the Roman Empire is challenged, however, by modern historians who see Rome as merely transforming from the Western Empire into barbarian kingdoms as the Western Emperors delegated themselves out of existence, and the East transforming into the Byzantine Empire, which only fell in 1453 AD.

North Africa's populous and flourishing civilization collapsed after exhausting its resources in internal fighting and suffering devastation from the invasion of the Bedouin tribes of Banu Sulaym and Banu Hilal.[2] Ibn Khaldun noted that the lands ravaged by Banu Hilal invaders had become completely arid desert.[3]

In the brutal pillaging that followed Mongol invasions, the invaders decimated the populations of China, Russia, the Middle East, and Islamic Central Asia. Later Mongol leaders, such as Timur, though he himself became a Muslim, destroyed many cities, slaughtered thousands of people and did irreparable damage to the ancient irrigation systems of Mesopotamia. These invasions transformed a civil society to a nomadic one.[4]

Encounters between European explorers and populations in the rest of the world often introduced local epidemics of extraordinary virulence. Smallpox ravaged Mexico in the 1520s, killing 150,000 in Tenochtitlán alone, including the emperor, and Peru in the 1530s, aiding the European conquerors.[5] Some believe that the death of up to 95% of the Native American population of the New World was caused by Old World diseases[6] although new research suggests tuberculosis from seals and sea lions played a significant part.[7] Live smallpox was also included in the ship inventories of the Australian first settlement, and a smallpox epidemic spread across the continent 3 years after European settlement.

Societal collapse of many indigenous cultures has occurred as a result of European imperialism in various parts of the globe, particularly in areas where European settler communities took possession of land once held by native peoples, in Latin America and North America, and in Australasia. The effects of this dispossession are still evident in many of the problems confronting indigenous cultures, including alcoholism, high rates of incarceration, suicide rates and fraternal violence.[citation needed]

Sub-replacement fertility

The Greek historian Polybius, writing in The Histories, largely blamed the decline of the Hellenistic world on low fertility rates:[8]
In our time all Greece was visited by a dearth of children and generally a decay of population, owing to which the cities were denuded of inhabitants, and a failure of productiveness resulted, though there were no long-continued wars or serious pestilences among us…. For this evil grew upon us rapidly, and without attracting attention, by our men becoming perverted to a passion for show and money and the pleasures of an idle life, and accordingly either not marrying at all, or, if they did marry, refusing to rear the children that were born, or at most one or two out of a great number, for the sake of leaving them well off or bringing them up in extravagant luxury.[9]
In a speech to Roman nobles, Emperor Augustus commented on the low birthrates of the Roman elite:[10]
How otherwise shall families continue? How can the commonwealth be preserved if we neither marry nor produce children? Surely you are not expecting some to spring up from the earth to succeed to your goods and to public affairs, as myths describe. It is neither pleasing to Heaven nor creditable that our race should cease and the name of Romans meet extinguishment in us, and the city be given up to foreigners,—Greek or even barbarians. We liberate slaves chiefly for the purpose of making out of them as many citizens as possible; we give our allies a share in the government that our numbers may increase: yet you, Romans of the original stock, including Quintii, Valerii, Iulli, are eager that your families and names at once shall perish with you.[11]
Upon the establishment of the Roman Empire, Augustus introduced legislation designed to increase the birthrate of the Roman nobility.[12]

Changes occurring with collapse

There are three main types of collapse:

Reversion/Simplification: A society's adaptive capacity may be reduced by either a rapid change in population or societal complexity, destabilizing its institutions and causing massive shifts in population and other social dynamics. In cases of collapse, civilizations tend to revert to less complex, less centralized socio-political forms using simpler technology. These are characteristics of a Dark Age. Examples of such societal collapse are: the Hittite Empire, the Mycenaean civilization, the Western Roman Empire, the Mauryan and Gupta Empires in India, the Mayas, the Angkor in Cambodia, the Han and Tang dynasties in China and the Mali Empire.

Incorporation/Absorption: Alternately, a society may be gradually incorporated into a more dynamic, more complex inter-regional social structure. This happened in Ancient Egypt and Mesopotamia, the Levantine cultures, the Mughal and Delhi Sultanates in India, Song China, the Aztec culture in Mesoamerica, the Inca culture in South America, and the modern civilizations of China, Japan, and India, as well as many modern states in the Middle East and Africa.

Obliteration: Vast numbers of people in the society die, or the birth rate plunges to a level that causes a dramatic depopulation.

Other changes that may accompany a collapse:
  • Destratification: Complex societies stratified on the basis of class, gender, race or some other salient factor become much more homogeneous or horizontally structured. In many cases past social stratification slowly becomes irrelevant following collapse and societies become more egalitarian.
  • Despecialization: One of the most characteristic features of complex civilizations (and in many cases the yardstick to measure complexity) is a high level of job specialization. The most complex societies are characterized by artisans and tradespeople who specialize intensely in a given task. Indeed, the rulers of many past societies were hyper-specialized priests or priestesses who were completely supported by the work of the lower classes. During societal collapse, the social institutions supporting such specialization are removed and people tend to become more generalized in their work and daily habits.
  • Decentralization: As power becomes decentralized, people tend to be more self-regimented and have many more personal freedoms. In many instances of collapse, there is a slackening of social rules and etiquette. Geographically speaking, communities become more parochial or isolated. For example, following the collapse of the Maya civilization, many Maya returned to their traditional hamlets, moving away from the large cities that had dominated the political landscape.
  • Destructuralization: Institutions, processes, and artifacts are all manifest in the archaeological record in abundance in large civilizations. After collapse, evidence of epiphenomena, institutions, and types of artifacts change dramatically as people are forced to adopt more self-sufficient lifestyles.
  • Depopulation: Societal collapse is almost always associated with a population decline. In extreme cases, the collapse in population is so severe that the society disappears entirely, such as happened with the Greenland Vikings, or a number of Polynesian islands. In less extreme cases, populations are reduced until a demographic balance is re-established between human societies and the depleted natural environment. A classic example is the city of Rome, which had a population of about 1.5 million at the peak of the Roman Empire during the reign of Trajan in the early 2nd century AD, but in the Early Middle Ages the population had declined to only around 15,000 inhabitants by the 9th century.

Population dynamics

In the general study of cultural change and population dynamics, a whole system displays complex ecosystem changes. Organizational adaptability relates importantly to organizational diversity.
Several key features of human societal collapse can be related to population dynamics[13]

Theories

The coupled breakdown of economic, cultural and social institutions with ecological relationships is perhaps the most common feature of collapse. In his book Collapse: How Societies Choose to Fail or Succeed, Jared Diamond proposes five interconnected causes of collapse that may reinforce each other: non-sustainable exploitation of resources, climate changes, diminishing support from friendly societies, hostile neighbors, and inappropriate attitudes for change.[14][15]

Joseph Tainter theorizes that collapsed societies essentially exhausted their own designs, and were unable to adapt to natural diminishing returns for what they knew as their method of survival.[16] It matches closely Toynbee's idea that "they find problems they can't solve".

Linking social/environmental dynamics

Modern social critics commonly interpret things like sedentary social behavior as symptomatic of societal decay, and link what appears to be laziness with the depletion of important non-renewable resources. However, many primitive cultures also have high degrees of leisure, so if that is a cause in one place it may not be in another—leisure or apparent laziness is then not a sufficient cause.

What produces modern sedentary life, unlike nomadic hunter-gatherers, is extraordinary modern economic productivity. Tainter argues that exceptional productivity is actually more the sign of hidden weakness, both because of a society's dependence on it, and its potential to undermine its own basis for success by not being self limiting as demonstrated in Western culture's ideal of perpetual growth.

As a population grows and technology makes it easier to exploit depleting resources, the environment's diminishing returns are hidden from view. Societal complexity is then potentially threatened if it develops beyond what is actually sustainable, and a disorderly reorganization were to follow. The scissors model of Malthusian collapse, where the population grows without limit and resources do not, is the idea of great opposing environmental forces cutting into each other.

For the modern world economy, for example, the growing conflict between food and fuel, depending on many of the same finite and diminishing resources, is visible in recent major commodity price shocks. It is one of the key relationships researchers, since the early studies of the Club of Rome, have been most concerned with.

Jared Diamond pursues these themes in his 2005 book Collapse: How Societies Choose to Fail or Succeed.[14]

Population pressure and mineral resource exhaustion

Romanian American economist Nicholas Georgescu-Roegen, a progenitor in economics and the paradigm founder of ecological economics, has argued that the carrying capacity of Earth — that is, Earth's capacity to sustain human populations and consumption levels — is bound to decrease sometime in the future as Earth's finite stock of mineral resources is presently being extracted and put to use; and consequently, that the world economy as a whole is heading towards an inevitable future collapse, leading to the demise of human civilisation itself.[17]

Georgescu-Roegen is basing his pessimistic prediction on the two following considerations:
  • According to his ecological view of 'entropy pessimism', matter and energy is neither created nor destroyed in man's economy, only transformed from states available for human purposes (valuable natural resources) to states unavailable for human purposes (valueless waste and pollution). In effect, all of man's technologies and activities are only speeding up the general march against a future planetary 'heat death' of degraded energy, exhausted natural resources and a deteriorated environment — a state of maximum entropy on Earth.
  • According to his social theory of 'bioeconomics', humanity's economic struggle to work and earn a livelihood is largely a continuation and extension of the biological struggle to sustain life and survive. This struggle manifests itself as a permanent social conflict that can be eliminated neither by man's decision to do so nor by the social evolution of mankind. Consequently, we are biologically unable to restrain ourselves collectively on a permanent and voluntary basis for the benefit of unknown future generations; the pressure of population on Earth's resources will nothing but increase.
Taken together, the Industrial Revolution in Britain in the second half of the 18th century has unintentionally thrust man's economy into a long, never-to-return overshoot-and-collapse trajectory with regard to the Earth's mineral stock. The world economy will continue growing until its inevitable and final collapse in the future. From that point on, Georgescu-Roegen conjectures, ever deepening scarcities will aggravate social conflict throughout the globe and ultimately spell the end of mankind itself.

Georgescu-Roegen was the paradigm founder of ecological economics and is also considered the main intellectual figure influencing the degrowth movement. Consequently, much work in these fields is devoted to discussing the existential impossibility of distributing Earth's finite stock of mineral resources evenly among an unknown number of present and future generations. This number of generations is likely to remain unknown to us, as there is little way of knowing in advance if or when mankind will eventually face extinction. In effect, any conceivable intertemporal distribution of the stock will inevitably end up with universal economic decline at some future point.[18]:369–371 [19]:253–256 [20]:165 [21]:168–171 [22]:150–153 [23]:106–109 [24]:546–549 [25]:142–145

Theories of energy return on energy invested

A related economic model is proposed by Thomas Homer-Dixon[26] and by Charles Hall[27] in relation to our declining productivity of energy extraction, or energy return on energy invested (EROEI). This measures the amount of surplus energy a society gets from using energy to obtain energy.

There would be no surplus if EROEI approaches 1:1. What Hall showed is that the real cutoff is well above that, estimated to be 3:1 to sustain the essential overhead energy costs of a modern society. Part of the mental equation is that the EROEI of our generally preferred energy source, petroleum, has fallen in the past century from 100:1 to the range of 10:1 with clear evidence that the natural depletion curves all are downward decay curves. An EROEI of more than ~3, then, is what appears necessary to provide the energy for societally important tasks, such as maintaining government, legal and financial institutions, a transportation infrastructure, manufacturing, building construction and maintenance and the life styles of the rich and poor that a society depends on.

The EROEI figure also affects the number of people needed for sustainable food production. In the pre-modern world, it was often the case that 80% of the population was employed in agriculture to feed a population of 100%, with a low energy budget. In modern times, the use of cheap fossil fuels with an exceedingly high EROEI enabled 100% of the population to be fed with only 4% of the population employed in agriculture. Diminishing EROEI making fuel more expensive relative to other things may require food to be produced using less energy, and so increases the number of people employed in food production again.

Models of societal response

According to Joseph Tainter[28] (1990), too many scholars offer facile explanations of societal collapse by assuming one or more of the following three models in the face of collapse:
  1. The Dinosaur, a large-scale society in which resources are being depleted at an exponential rate and yet nothing is done to rectify the problem because the ruling elite are unwilling or unable to adapt to those resources' reduced availability: In this type of society, rulers tend to oppose any solutions that diverge from their present course of action. They will favor intensification and commit an increasing number of resources to their present plans, projects, and social institutions.
  2. The Runaway Train, a society whose continuing function depends on constant growth (cf. Frederick Jackson Turner's Frontier Thesis): This type of society, based almost exclusively on acquisition (e.g., pillage or exploitation), cannot be sustained indefinitely. The Assyrian, Roman and Mongol Empires, for example, both fractured and collapsed when no new conquests could be achieved.
    Tainter argues that capitalism can be seen as an example of the Runaway Train model, in that generally accepted accounting practices require publicly traded companies, along with many privately held ones, to exhibit growth as measured at some fixed interval (often three months). Moreover, the ethos of consumerism on the demand side and the practice of planned obsolescence on the supply side encourage the purchase of an ever-increasing number of goods and services even when resource extraction and food production are unsustainable if continued at current levels.
  3. The House of Cards, a society that has grown to be so large and include so many complex social institutions that it is inherently unstable and prone to collapse. This type of society has been seen with particular frequency among Eastern bloc and other communist nations, in which all social organizations are arms of the government or ruling party, such that the government must either stifle association wholesale (encouraging dissent and subversion) or exercise less authority than it asserts (undermining its legitimacy in the public eye).
    By contrast, as Alexis de Tocqueville observed, when voluntary and private associations are allowed to flourish and gain legitimacy at an institutional level, they complement and often even supplant governmental functions: They provide a "safety valve" for dissent, assist with resource allocation, provide for social experimentation without the need for governmental coercion, and enable the public to maintain confidence in society as a whole, even during periods of governmental weakness.

Tainter's critique

Tainter argues that these models, though superficially useful, cannot severally or jointly account for all instances of societal collapse. Often they are seen as interconnected occurrences that reinforce each other.
Ahu Tongariki near Rano Raraku, a 15-moai ahu excavated and restored in the 1990s

For example, the failure of Easter Island's leaders to remedy rapid ecological deterioration cannot be understood without reference to the other models above. The islanders, who erected large statues called moai as a form of religious reverence to their ancestors, used felled trees as rollers to transport them. Because the islanders firmly believed that their displays of reverence would lead to increased future prosperity, they had a deeply entrenched incentive to intensify moai production. Because Easter Island's geographic isolation made its resources hard to replenish and made the balance of its overall ecosystem very delicate ("House of Cards"), deforestation led to soil erosion and insufficient resources to build boats for fishing or tools for hunting. Competition for dwindling resources resulted in warfare and many casualties (an additional "Runaway Train" iteration). Together these events led to the collapse of the civilization, but no single factor above provides an adequate account.

Mainstream interpretations of the history of Easter Island also include the slave raiders who abducted a large proportion of the population and epidemics that killed most of the survivors (see Easter Island History#Destruction of society and population.) Again, no single point explains the collapse; only a complex and integrated view can do so.

Tainter's position is that social complexity is a recent and comparatively anomalous occurrence requiring constant support. He asserts that collapse is best understood by grasping four axioms. In his own words (p. 194):
  1. human societies are problem-solving organizations;
  2. sociopolitical systems require energy for their maintenance;
  3. increased complexity carries with it increased costs per capita; and
  4. investment in sociopolitical complexity as a problem-solving response reaches a point of declining marginal returns.
With these facts in mind, collapse can simply be understood as a loss of the energy needed to maintain social complexity. Collapse is thus the sudden loss of social complexity, stratification, internal and external communication and exchange, and productivity.

Toynbee’s theory of decay

The British historian Arnold J. Toynbee, in his 12-volume magnum opus A Study of History (1961), theorized that all civilizations pass through several distinct stages: genesis, growth, time of troubles, universal state, and disintegration. (Carroll Quigley would expand on and refine this theory in his "The Evolution of Civilizations".[29])

Toynbee argues that the breakdown of civilizations is not caused by loss of control over the environment, over the human environment, or attacks from outside. Rather, societies that develop great expertise in problem solving become incapable of solving new problems by overdeveloping their structures for solving old ones.

The fixation on the old methods of the "Creative Minority" leads it to eventually cease to be creative and degenerates into merely a "dominant minority" (that forces the majority to obey without meriting obedience), failing to recognize new ways of thinking. He argues that creative minorities deteriorate due to a worship of their "former self," by which they become prideful, and fail to adequately address the next challenge they face.

He argues that the ultimate sign a civilization has broken down is when the dominant minority forms a Universal State, which stifles political creativity. He states:
First the Dominant Minority attempts to hold by force - against all right and reason - a position of inherited privilege which it has ceased to merit; and then the Proletariat repays injustice with resentment, fear with hate, and violence with violence when it executes its acts of secession. Yet the whole movement ends in positive acts of creation - and this on the part of all the actors in the tragedy of disintegration. The Dominant Minority creates a universal state, the Internal Proletariat a universal church, and the External Proletariat a bevy of barbarian war-bands.
He argues that, as civilizations decay, they form an "Internal Proletariat" and an "External Proletariat." The Internal proletariat is held in subjugation by the dominant minority inside the civilization, and grows bitter; the external proletariat exists outside the civilization in poverty and chaos, and grows envious. He argues that as civilizations decay, there is a "schism in the body social," whereby abandon and self-control together replace creativity, and truancy and martyrdom together replace discipleship by the creative minority.

He argues that in this environment, people resort to archaism (idealization of the past), futurism (idealization of the future), detachment (removal of oneself from the realities of a decaying world), and transcendence (meeting the challenges of the decaying civilization with new insight, as a Prophet). He argues that those who Transcend during a period of social decay give birth to a new Church with new and stronger spiritual insights, around which a subsequent civilization may begin to form after the old has died.

Toynbee's use of the word 'church' refers to the collective spiritual bond of a common worship, or the same unity found in some kind of social order.

The great irony expressed by these and others like them is that civilizations that seem ideally designed to creatively solve problems, find themselves doing so self-destructively.

Systems science

Researchers, as yet, have very little ability to identify internal structures of large distributed systems like human societies, which is an important scientific problem. Genuine structural collapse seems, in many cases, the only plausible explanation supporting the idea that such structures exist. However, until they can be concretely identified, scientific inquiry appears limited to the construction of scientific narratives,[30] using systems thinking for careful storytelling about systemic organization and change.

History includes many examples of the appearance and disappearance of human societies with no obvious explanation. The abrupt dissolution of the Soviet Union in the course of a few months, without any external attack, according to Johan Galtung was due to growing structural contradictions brought on by geopolitical overreach, which could not be resolved within the existing socio-political systems.

Although a societal collapse is generally an endpoint for the administration of a culture's social and economic life, societal collapse can also be seen as simply a change of administration within the same culture. Russian culture would seem to have outlived both the society of Imperial Russia and the society of the Soviet Union, for example. Frequently the societal collapse phenomenon is also a process of decentralization of authority after a 'classic' period of centralized social order, perhaps replaced by competing centers as the central authority weakens. Societal failure may also result in a degree of empowerment for the lower levels of a former climax society, who escape from the burden of onerous taxes and control by exploitative elites. For example, the black plague contributed to breaking the hold of European feudal society on its underclass in the 15th century.
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