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Western lowland gorilla (Gorilla gorilla gorilla)
photo © M. Watson / www.ardea.com

SPECIES EXTINCTION
A natural (and unnatural) process

The world is, and always has been, in a state of flux. Over hundreds of millions of years, continents have broken apart, oceans appeared, mountains formed and worn away. With geological change come changes in living things: species, populations, and whole lineages disappear, and new ones emerge. Extinction is therefore a natural process. According to the fossil record, no species has yet proved immortal; as few as 2-4% of the species that have ever lived are believed to survive today. The remainder are extinct, the vast majority having disappeared long before the arrival of humans. But the rapid loss of species we are seeing today is estimated by experts to be between 1000 and 10,000 times higher than the “background” or expected natural extinction rate (a highly conservative estimate). Unlike the mass extinction events of geological history, the current extinction phenomenon is one for which a single species - ours - appears to be almost wholly responsible. This is often referred to as “the sixth extinction crisis”, after the five known extinction waves in geological history. The number of species known to be threatened with extinction has topped 16,000. Their ranks include familiar species like the polar bear, hippopotamus, sharks, freshwater fish and Mediterranean flowers. Marine species are proving to be just as much at risk as their landbased Counterparts.

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