Extinction
Extinction is the end of a species, usually marked at the death of the last individual of that species, though most species become functionally extinct through lack of a stable breeding population long before actual extinction. Because the Earth is some 4.5 billion years old, nearly all species that have ever existed on it have become extinct, though nearly all of these weren't wiped out in some catastrophe or deliberately exterminated: most species simply breed out into the next phase of evolution.
Most species that have become extinct died out millions of years before the first definitive human ancestors, let alone before the dawn of civilization; nothing could have been done to save these species, but it's important to preserve those that still exist for both the planet and for future generations. |
Mass Extinctions
Throughout history, several mass extinctions (or biotic crises) have occurred which resulted in a severe drop-off of biodiversity in their time, often resulting in a total rearrangement of the natural order--the Great Dying, for example, eventually led to the rise of the dinosaurs. The most famous of these extinction events, the |KT Extinction|, took place c. 65 million years ago and wiped out the non-avian dinosaus and many other groups as well, paving the way for the mammals and, eventually, humanity. This, in turn, eventually led to the ongoing Anthropocene Extinction as, along with climate change occurring at the end of the Last Glacial Period, archaic humans contributed to the extinction of many megafauna species from overhunting and possibly even some other archaic humans such as the Neanderthals, though many archaic humans were gradually absorbed into the genome of Homo sapiens and "still exist" in the DNA of modern humans. The Anthropocene Extinction continued over the following millennia but became accelerated by the anthropogenic climate change that accompanied industrialization starting in the Modern Age, but in recent centuries efforts have been made to counter this through the conservation movement.
Mankind itself was nearly subjected to a naturally-occurring extinction event known as the Toba catastrophe, a massive volcanic eruption which took place on Sumatra, in Indonesia, c. 75,000 years ago and caused a volcanic winter that lasted 6-10 years. Humanity narrowly avoided extinction by inbreeding in the genetic bottleneck that resulted from this and ultimately survived the event.
Mankind itself was nearly subjected to a naturally-occurring extinction event known as the Toba catastrophe, a massive volcanic eruption which took place on Sumatra, in Indonesia, c. 75,000 years ago and caused a volcanic winter that lasted 6-10 years. Humanity narrowly avoided extinction by inbreeding in the genetic bottleneck that resulted from this and ultimately survived the event.
Recent Extinctions
While mankind today often takes great strides to preserve Earth's biodiversity, it wasn't always that way: while plants and animals would occasionally die out throughout human history, such as the gradual disappearance of lions from the Balkan Peninsula, many species from about 1500 onwards were wiped out for various reasons. Some were perceived as threats and deliberately exterminated to protect human interests; some were wiped out by foreign species that traveled with sailors such as cats and rats; and others evolved in isolation and didnt recognize humans as a threat, making them exceptionally vulnerable to overhunting. Part of this was because, for centuries, it was believed (at least in Christendom) that God would never allow one of His creations to simply disappear, and so no efforts were made to protect them from extermination. Once it became clear that extinction could happen, conservation movements attempted to save species threatened with it. Sometimes this would succeed, and sometimes it wouldn't.
Localized Extinction
While many species have become completely extinct, some have survived outside their native range, or sometimes in areas where they were introduced for one reason or another. Many of these qualify as being extinct in the wild, such as the Barbary lion (from habitat loss and extirpation) and the Grévy's zebra, (because of the diversion of water from its natural habitat for human use, which was stressed by the effects of climate change) though some live essentially as protected wild animals, such as the heath hen's survival in Martha's Vineyard after dying out in its native range from the continual spread of mankind and unnatural predators of the hen along with them.
Extinct Species
- Aepyornis maximus, the elephant bird, was a giant flightless bird native to |Madagascar| and is thought to be the grain of truth behind the legendary roc, a bird said to be so gigantic that it would carry off whole elephants to feed its chicks. Most closely related to the diminutive kiwi, the elephant bird died out c. 1000 AD, and is generally thought to have gone extinct because of the arrival of humans on |Madagascar|, though the exact causes are unclear--evidence indicates that their eggs were regular meals, and it's also thought that the birds themselves may have been hunted for food or that they were afflicted by diseases transmitted by the domesticated fowl brought over the by the first inhabitants of the island.
- Arctodus simus, also known as the short-faced bear, was a relative of the modern spectacled bear which roamed North America. A victim of the inevitable progress of time long before the dawn of civilization, Arctodus and nearly all of its related species died out some 11,000 years ago.
- Bos primigenius, the aurochs, has been extinct since approximately 1627; it was the wild ancestor of the domestic cattle. Though survived by its domesticated descendants and even the subject of a selective breeding program to resurrect it, most cattle today hardly measure up to the aurochs--in his Gallic War Commentaries, Julius Caesar compared them in size to an elephant.
- Dusicyon australis, also known as the warrah, was the only land mammal native to |the Falklands|, originally thought to be a relative of the culpeo but now believed to be closer to the maned wolf. They were notably observed by Charles Darwin, whose 1865 prediction that it would soon become extinct because of its highly-desired fur and livestock predation was confirmed in 1880
- Equus ferus ferus, the tarpan or Eurasian wild horse, lived throughout Europe except for Erinstèr, Iceland, and parts of the Scandinavian Peninsula; it was the wild ancestor of the domestic horse. The last known tarpan died in captivity in Russia in 1909, but Heinz and Lutz Heck made an effort to recreate the species starting in the mid-20th century, resulting in the Heck horse.
- Hieraatus moorei, (formerly classified as Harpagornis) or the Haast's eagle, is the largest eagle known to have ever lived, inhabiting the South Island of |New Zealand| until c. 1400 AD. It was the apex predator of its environment, which was famously populated almost exclusively by birds until the Māori people arrived, hunting the more famous and flightless moa. Like Aepyornis, the moas' eggs and meat were easy food for the Māori settlers, rapidly driving the moas to extinction; when the moas died out, so did the Haast's eagle.
- Megalonyx was a genus of ground sloths which lived all over what is now Anahuac and the United States; Thomas Jefferson was aware of them from 1796 thanks to Megalonyx fossils found in eastern America and was knowledgeable enough to compare them to the South American Megatherium. He even believed that they still lived further west in then-unexplored interior of North America and instructed to Lewis & Clark Expedition to try to find one. It's since been confirmed that the Megalonyx died out around 9000 BC.
- Panthera atrox, also known as the American lion, stalked the savannahs and grasslands of the prehistoric Americas much like its modern namesake after crossing the Bering Land Bridge from Eurasia more than 300,000 years ago. Like many megafaunal animals, they died out c. 9000 BC, around the end of the Ice Age.
- Raphus cucullatus, better known as the dodo, was a flightless bird most closely related to pigeons and doves which was found only on the island of |Mauritius|. Essentially the poster child for the Anthropocene Extinction, such that "dead as the dodo" is a common expression to this day, it's actually a misconception that the dodo was hunted to extinction for its meat--the dodo was unpalatable and it was actually wiped out by introduced species such as rats.
De-extinction
Remarkably, it's now possible to resurrect certain animals from extinction. While cloning is the most widely-proposed method, selective breeding has also been proposed, with the aurochs and tarpan being two concurrent examples of this; this method is also known as "breeding-back," and it's been suggested that the dodo, moa, and thylacine could be brought back in this way. The woolly mammoth, Mammuthus primigenius, is thought to be on its way back to existence through a combination of genetic engineering and the selective breeding of Asian elephants. It's also been suggested that dinosaurs could be brought back not by extracting DNA from amber like in |Michael Crichton's Jurassic Park| but by activating dormant genes in living birds to produce facsimiles of them. The most notable example, though, was the successful cloning of the Pyrenean ibex, Capra pyrenaica pyrenaica, which became extinct in January 2000 but was brought back by implanting somatic cells into a related species, though the specimen died shortly after being born.
In a more mundane case of de-extinction, some organizations and even countries have enacted rewilding projects where animals are introduced to their former ranges. In some cases, though, certain animals have been used as proxies for extinct relatives, such as the introduction of the endangered Bengal tiger to Central Asia as a proxy for the extinct Caspian tiger or the Bornean elephant to California's Channel Islands as a stand-in for the pygmy mammoths which formerly lived in the region. The main principle of rewilding is to rebuild ecosystems from a current, damaged state which resulted from certain extinctions; the potential reintroduction of genetically-engineered mammoths to the Siberian steppes is one example of this, as plants in the region which were mainly eaten by prehistoric mammoths still exist and the presence of modern mammoths likely wouldn't have a negative impact on the environment.
In a more mundane case of de-extinction, some organizations and even countries have enacted rewilding projects where animals are introduced to their former ranges. In some cases, though, certain animals have been used as proxies for extinct relatives, such as the introduction of the endangered Bengal tiger to Central Asia as a proxy for the extinct Caspian tiger or the Bornean elephant to California's Channel Islands as a stand-in for the pygmy mammoths which formerly lived in the region. The main principle of rewilding is to rebuild ecosystems from a current, damaged state which resulted from certain extinctions; the potential reintroduction of genetically-engineered mammoths to the Siberian steppes is one example of this, as plants in the region which were mainly eaten by prehistoric mammoths still exist and the presence of modern mammoths likely wouldn't have a negative impact on the environment.