What is extinction in biology?
Extinction is the termination of a species through the death of its last member. A species can become functionally extinct even earlier, once the few survivors can no longer reproduce and recover.
Questions about Extinction
Short answers, pulled from the story.
How many species have gone extinct in Earth's history?
Over five billion species are estimated to have died out across the history of life. More than 99.9% of all species that ever lived are now extinct, and the average species lifespan is 1 to 10 million years.
What is a Lazarus taxon and what is the most famous example?
A Lazarus taxon is a species thought to be extinct that is later rediscovered. The coelacanth is a famous example, known only from fossils and presumed gone since the Cretaceous until a living specimen was found off the Chalumna River in South Africa in 1938.
What are the main causes of species extinction today?
Habitat degradation is currently the main human-driven cause of species extinctions, led by agriculture and followed by urban sprawl, logging, mining, and some fishing practices. Other causes include genetic pollution, climate change, coextinction, and the introduction of invasive species.
How many mass extinctions have there been and what caused the dinosaur extinction?
There have been at least five mass extinctions in the history of life on earth. The Cretaceous-Paleogene extinction event 66 million years ago wiped out the non-avian dinosaurs, while the Permian-Triassic event about 250 million years ago killed an estimated 90% of species.
Who established the modern scientific understanding of extinction?
Georges Cuvier is credited with establishing the modern conception of catastrophic extinction in an 1796 lecture to the French Institute. His view was vindicated in 1982 when David Raup and Jack Sepkoski published their seminal paper on mass extinctions.
Why did people once refuse to believe extinction was possible?
Before the 19th century much of Western society believed in the great chain of being, which linked all life in a continuous chain and made extinction impossible without breaking the natural order. Thomas Jefferson famously denied the extinction of the woolly mammoth, arguing that nature never allows a race of animals to become extinct.