Holocene extinction: Wikis

Advertisements
  
  

Note: Many of our articles have direct quotes from sources you can cite, within the Wikipedia article! This article doesn't yet, but we're working on it! See more info or our list of citable articles.

Encyclopedia

From Wikipedia, the free encyclopedia

The dodo, a bird of Mauritius, became extinct during the mid-late seventeenth century after humans destroyed the forests where the birds made their homes and introduced mammals that ate their eggs.

The Holocene extinction is the widespread, ongoing extinction of species during the present Holocene epoch. The large number of extinctions span numerous families of plants and animals including mammals, birds, amphibians, reptiles and arthropods; a sizeable fraction of these extinctions are occurring in the rainforests. Between 1500 and 2009 CE, 875 extinctions have been documented by the International Union for Conservation of Nature and Natural Resources.[1] However, since most extinctions go undocumented, scientists estimate that during the 20th century, between 20,000 and two million species actually became extinct, but the precise total cannot be determined more accurately within the limits of present knowledge. Up to 140,000 species per year (based on Species-area theory)[2] may be the present rate of extinction based upon upper bound estimating.

In broad usage, Holocene extinction includes the notable disappearance of large mammals, known as megafauna, starting 10,000 years ago as humans developed and spread. Such disappearances have normally been considered as either a response to climate change, a result of the proliferation of modern humans, or both; however in 2007 a cometary impact hypothesis was presented, but has not been broadly accepted. These extinctions, occurring near the Pleistocene–Holocene boundary, are sometimes referred to as the Quaternary extinction event or Ice Age extinction. However the Holocene extinction may be regarded as continuing into the 21st century.

There is no general agreement on whether to consider more recent extinctions as a distinct event or merely part of a single escalating process. Only during these most recent parts of the extinction have plants also suffered large losses. Overall, the Holocene extinction is most significantly characterised by the presence of human-made driving factors.

Contents

The prehistoric extinction events

The ongoing extinction seems more outstanding in light of separating recent extinctions (approximately since the industrial revolution) from the Pleistocene extinction near the end of the last glacial period. The latter is exemplified by the extinction of the woolly mammoth and, incorrectly, the Neanderthal people.

However, modern climatology suggests the current Holocene epoch is no more than the latest in a series of interglacial intervals. Furthermore, there is a continuum of extinctions since 11,000 years BCE. If only considering human impact, the vulnerability and extinction rate of species simply rises with the increase in human population, so there would be no need to separate the Pleistocene extinction from the recent one. Nevertheless, the Pleistocene extinction event is large enough and has not been resolved completely.

Advertisements

Younger extinctions

New Zealand

c. CE 1500, several species became extinct after Polynesian settlers arrived, including:

Pacific, including Hawaii

Recent research, based on archaeological and paleontological digs on 70 different islands, has shown that numerous species went extinct as people moved across the Pacific, starting 30,000 years ago in the Bismarck Archipelago and Solomon Islands (Steadman & Martin 2003). It is currently estimated that among the bird species of the Pacific some 2000 species have gone extinct since the arrival of humans (Steadman 1995). Among the extinctions were:

Madagascar

Starting with the arrival of humans in the first century BCE or first century CE, nearly all of the island's megafauna became extinct, including:

Indian Ocean Islands

Starting c. 1500 CE, a number of species became extinct upon human settlement of the islands, including:

Ongoing Holocene extinction

Significantly, the rate of species extinctions was estimated in 1995 at 100 times "background" or average extinction rates in the evolutionary time scale of planet Earth.[3]

Megafaunal extinctions continue into the 21st century. Modern extinctions are more directly attributable to human influences. Extinction rates are minimized in the popular imagination by the survival of captive populations of animals that are extinct in the wild (Père David's Deer, etc.), by marginal survivals of highly-publicized megafauna that are ecologically extinct (the Giant Panda, Sumatran Rhinoceros, North American Black-Footed Ferret, etc.) and by extinctions among arthropods. Some notable examples of modern extinctions of "charismatic" mammal fauna include:

Many birds have become extinct as a result of human activity, especially birds endemic to islands, including many flightless birds (see a more complete list under extinct birds). Notable extinct birds include:

A few biologists believe that we are at this moment at the beginning of an accelerated anthropogenic extinction.[4] E.O. Wilson of Harvard, in The Future of Life (2002), estimates that at current rates of human disruption of the biosphere, one-half of all species of life will be extinct by 2100. In 1998 the American Museum of Natural History conducted a poll of biologists that revealed that the vast majority of biologists believe that we are in the midst of an anthropogenic extinction. Numerous scientific studies since then—such as a 2004 report from Nature,[5] and those by the 10,000 scientists who contribute to the IUCN's annual Red List of threatened species—have only strengthened this consensus.

Peter Raven, past President of the American Association for the Advancement of Science, states in the foreword to their publication AAAS Atlas of Population and Environment:[6] "We have driven the rate of biological extinction, the permanent loss of species, up several hundred times beyond its historical levels, and are threatened with the loss of a majority of all species by the end of the 21st century."[7] Some of the reasons for the current extinctions are human related and include deforestation and other habitat destruction, hunting and poaching, the introduction of non-native species, pollution and climate change. .[8]

The Golden Toad of Costa Rica, extinct since around 1989. Its disappearance has been attributed to a confluence of several factors, including El Niño warming, fungus, and the introduction of invasive species.

There was a limited debate as to the extent to which the disappearance of megafauna at the end of the last glacial period can also be attributed to human activities, directly, by hunting, or indirectly, by decimation of prey populations. While climate change is still cited as another important factor, anthropogenic explanations have become predominant.

189 countries which are signatory to the Rio Accord have committed to preparing a Biodiversity Action Plan, a first step at identifying specific endangered species and habitats, country by country.

Human influence on extinction

Extinction of animals and plants caused by human actions may go as far back as the late Pleistocene.[9] Extinctions that are due to human activity (anthropogenic), particularly hypothesized future events, have also been labelled the anthropocene extinction.[10][11] The Anthropocene is a term introduced in 2000.

Recent extinctions described are well-documented,[9] but the nomenclature used varies. The term Anthropocene is a term that is used by few scientists,[9] and some commentators may refer to the current and projected future extinctions as part of a longer Holocene extinction,[12] which incorporates both the earlier Quaternary extinction and the later Anthropocene extinction.[citation needed] The Holocene-Anthropocene boundary is contested, with some commentators asserting significant human influence on climate for much of what is normally regarded as the Holocene Epoch.[13] Other commentators place the Holocene-Anthropocene boundary at the industrial revolution while also saying that "Formal adoption of this term in the near future will largely depend on its utility, particularly to earth scientists working on late Holocene successions. "[9]

The extinction of megaherbivores in the late Pleistocene is explained by one of two hypotheses, or a combination of the two: climate change, and the ecological impact of early humans. Not only hunting, but anthropogenic fire selected for the survival of ruminants more than the survival of browsing mammals, and against carnivores and scavengers which fed on both.[14][15][16]

See also

References

  1. ^ Summary of the 2009 update of the IUCN Red List, http://www.iucn.org/media/materials/releases/?4143/Extinction-crisis-continues-apace
  2. ^ S.L. Pimm, G.J. Russell, J.L. Gittleman and T.M. Brooks, The Future of Biodiversity, Science 269: 347–350 (1995)
  3. ^ J.H.Lawton and R.M.May, Extinction Rates, Oxford University Press, Oxford, UK
  4. ^ http://www.amnh.org/museum/press/feature/biofact.html
  5. ^ Study sees mass extinctions via warming. MSNBC. URL accessed July 26, 2006.
  6. ^ "Atlas of Population and Environment". AAAS. 2000. http://atlas.aaas.org/. Retrieved 2008-02-12. 
  7. ^ "Atlas of Population and Environment, Foreword". AAAS. 2000. http://atlas.aaas.org/index.php?sub=foreword. Retrieved 2008-02-12. 
  8. ^ Measuring extinction, species by species
  9. ^ a b c d Zalasiewicz, J.; Williams, M.; Smith, A.; Barry, T. L.; Coe, A. L.; Bown, P. R.; Brenchley, P.; Cantrill, D. et al. (2008). "Are we now living in the Anthropocene". GSA Today 18: 4–5. doi:10.1130/GSAT01802A.1.  edit
  10. ^ Wooldridge, S. A. (9 June 2008). "Mass extinctions past and present: a unifying hypothesis". Biogeosciences Discuss (Copernicus) 5: 2401–2423. http://www.biogeosciences-discuss.net/5/2401/2008/bgd-5-2401-2008.html. 
  11. ^ Jackson, J. B. C. (Aug 2008). "Colloquium paper: ecological extinction and evolution in the brave new ocean" (Free full text). Proceedings of the National Academy of Sciences of the United States of America 105 Suppl 1: 11458–11465. doi:10.1073/pnas.0802812105. ISSN 0027-8424. PMID 18695220. PMC 2556419. http://www.pnas.org/cgi/pmidlookup?view=long&pmid=18695220.  edit
  12. ^ Elewa, Ashraf M. T.. "14". Mass Extinction. pp. 191–194. ISBN 978-3-540-75915-7 (Print) 978-3-540-75916-4 (Online). http://www.springerlink.com/content/t576492604428l55/. 
  13. ^ [1]
  14. ^ Martin P. S. (1963). The last 10,000 years: A fossil pollen record of the American Southwest. Tucson, AZ: Univ. Ariz. Press. ISBN 0-8165-1759-2. 
  15. ^ Martin P. S. (1967). Prehistoric overkill. In Pleistocene extinctions: The search for a cause (ed. P.S. Martin and H.E. Wright). New Haven: Yale Univ. Press. ISBN 0-300-00755-8. 
  16. ^ Martin P. S. (1989). Prehistoric overkill: A global model. In Quaternary extinctions: A prehistoric revolution (ed. P.S. Martin and R.G. Klein). Tucson, AZ: Univ. Arizona Press. pp. 354–404. ISBN 0-8165-1100-4. 

Further reading

External links


Simple English

The Holocene extinction is the human-caused mass extinction of nearly all currently living species. habitat destruction and over-harvesting are two of the primary causes which drive species extinct. Only 15% of all life has ever been discovered, yet animal species are dying by the millions yearly. This is preventable if mass pollution and mass consumption of the rain forests comes to an end. Sustainable lumber harvesting practices Need to become the norm in countries such as Brazil, China and India.

The Holocene extinction event is one of the greatest dangers mankind faces today. If it is allowed to continue unhindered it will reach the "Omega Point" where all ecosystems on the planet will profoundly collapse, leaving the planet uninhabitable to humans and barren of vital resources like soil, fish and game animals for hundreds of millions of years.

If this does not become a global priority within the next twenty to thirty years, there is a real danger of reaching the Omega Point.

America's forests were almost entirely destroyed in around 200 years. A completely virgin continent of wilderness before the settlers arrived, now America's natural herds of bison which once number in the tens of millions have been reduced to a population of around 200,000. Bald Eagles have similarly suffered a 99% decline in their population since European settlers arrived.

The majority of our medicines come from exotic plants and animals, such as the horseshoe crab whose blue blood is used to test for impurities in new medical vaccines. Every insignificant seeming bird or insect we drive extinct yearly could have potentially contained a cure for cancer, conceivably even a key to greatly extending human life capacities or fundamentally improving the quality of life for people the world over.


Advertisements






Got something to say? Make a comment.
Your name
Your email address
Message