The Sixth Extinction D id you know that most of the species that have ever lived on Earth are now extinct Did you know that the majority of life on Earth has never been known to us Every day many species of animals perhaps hundreds become extinct without us even knowing they existed Throughout the Earth’s history species have become extinct due to natural causes Scientists recognize that there have been five mass extinctions caused by astronomical geological or volcanic events Each of these extinctions wiped out between 50 and 95 percent of the wildlife of the time The most recent of these was about 65 million years ago when a giant asteroid is thought to have collided with the Earth This brought about the extinction of three quarters of the Earth’s animal species including the dinosaurs After a mass extinction like this it takes at least 10 million years for the biological diversity to recover Ammonites were marine mollusks that lived hundreds of millions of years ago They became extinct at the same time as the dinosaurs about 65 million years ago Their fossilized remains are found throughout the world 4
Today we are living in the middle of a sixth great extinction Unlike the others this one has a different cause human activity It probably began 50,000 years ago when early humans started to migrate around the world and began hunting with Stone Age weapons Since the 1600s more than 250 large animal species became extinct every one caused by humans Over 16,000 more are threatened with extinction This loss is due to the damage and pollution of the environment loss of habitats overhunting agriculture and the introduction of alien species Once an animal species is extinct it is gone forever We need to act now to conserve the amazing biodiversity on our planet and to ensure it will be there for future generations In the Americas the hunting activities of early humans eventually caused a continent-wide extinction of animals such as saber-toothed cats wild horses and ground sloths a fossilized skeleton of which is seen here HOT SPOT Last One Left George the tortoise below is the very last of a species of Galapagos island giant tortoise He lives on the island of Pinta and has been in captivity for 36 years He is literally the rarest animal in the world 5
Overhunting of Animals E ver since early people learned how to make weapons humans have hunted animals for their hides meat and bones They often had no knowledge of what damage they were doing to the animal populations and hunted many to extinction Already Extinct The passenger pigeon was once probably the most numerous bird on the planet It lived in North America and flew in flocks so large that they darkened the sky for hours and sometimes days as they passed overhead It was driven to extinction by uncontrolled hunting by early European settlers in the 1800s A species that once numbered more than four billion individuals was gone in a few decades American Bison The American bison was almost hunted to extinction in the nineteenth century by Native American people and European settlers who wanted their meat and hides Bison hunting was big business and whole herds were killed daily One professional hunter alone killed more than 20,000 animals Eventually as the great herds disappeared plans were made to save the bison From a small number of privately owned herds the bison population began to recover and now they are no longer endangered How can you help Buy fish that come from marine stocks that aren’t being overfished If you eat tuna only buy line-caught skipjack tuna Approximately 3,500 bison live in Yellowstone National Park today These animals are descendents of the small population of 23 bison that survived the mass slaughter of the 1800s
Whale Hunting Whales have been heavily hunted for many years for their meat blubber baleen and whale oil Now many species are endangered and face extinction Conservation methods include setting hunting quotas declaring the Indian Ocean a whale sanctuary and protecting the seven most endangered species But whales reproduce slowly For example the right whale has been protected for more than 50 years and still numbers less than 400 animals Fishing for tuna is done on an industrial scale Some tuna ships take 3,000 tons of fish out of the sea in a single trip Here a Greenpeace boat makes a protest against the Albatuna Tres the world’s largest tuna fishing vessel Animal Status Today overhunting is pushing many animals to the brink of extinction The International Union for Conservation of Nature has a scale that shows the status of animals in the wild Extinct Extinct in the wild Critically endangered Endangered Vulnerable Near threatened Least concern none of the species is left at all none of the species survive in the wild but some exist in captivity the species faces a high risk of being extinct very soon the species is in danger of becoming extinct not yet classified as endangered but numbers are dropping species numbers may be dropping species numbers are stable 7
