card
031

Extinction

OLogy Series
biology
card
031

Extinction

OLogy Series
biology

An animal or plant becomes extinct when the last of its kind dies. Since the beginning of life on Earth, countless plants, animals, and other organisms have become extinct. In fact, most species that have lived on Earth are now gone. Extinction occurs in the blink of an eye, but factors leading up to it can build up over thousands of years.

The Disappearance of the Mammoth
About 100,000 years ago, mammoths—large, hairy, elephant-like creatures—roamed in herds across much of the globe. Around 11,000 years ago, mammoths suddenly became extinct, except for one last population that lived over 7,000 years longer than the rest. This last group disappeared 3,700 years ago. Why did the mammoths become extinct? To answer this question, Museum scientist Ross MacPhee went to Siberia, the last home of the mammoths. By studying fossils, he hopes to test the theory that disease may have caused their extinction. Solving this mystery is important because finding out what caused extinctions in the past may help us prevent them from happening in the future.

How the Passenger Pigeon Became Extinct
About 300 years ago, billions of passenger pigeons lived on Earth. When gigantic flocks of these birds migrated, they could block out sunlight for hours. When large groups of these pigeons roosted, the limbs they sat on would sometimes snap from the weight of so many birds. In the 1800s, killing these birds for food became big business. In 1869, over one billion birds were killed in Michigan alone. Heavy hunting and the destruction of its breeding habitat caused the passenger pigeon to die out. In 1914, the last known passenger pigeon (named Martha) died in a zoo. Due to direct human impact, the most abundant bird in the world became extinct in a matter of decades.

What is the greatest cause of extinction today?

overhunting

destruction of habitat

not enough exercise

Are you right?

Correct!

Many plants and animals can't survive when their habitat changes quickly. Human activities such as mining and cutting down forests for farming or grazing destroy habitats.

Mike Novacek
paleontologist

Because of human activity, we are losing many species of animals to extinction at an alarming rate.

There have been five great mass extinctions in the history of life on Earth.

Fact
or
Fiction
?

Fact

These five mass extinctions have had a major effect on the evolution of life.

Pronunciation: x-TINK-shun
Name Origin: from the Latin extinctus, which means "to extinguish"
Description: Species of plants and animals are evolving every day, and many species are also disappearing, or becoming extinct. Sometimes human activity interferes with and speeds up these processes.
Significance: Extinction is permanent. There's no coming back from being extinct!

Image credits: courtesy of Discovery Channel Online; Mike Novacek: courtesy of Discovery Channel Online.