Ambitious projects aim to put dire wolves, woolly mammoths and passenger pigeons back into our ecosystems. But with so many technical and ethical hurdles, what is the real motivation?

A quarter of the world’s freshwater animals are threatened with extinction, new research shows New research shows about a quarter of animals living in rivers, lakes and other freshwater sources ...

Nearly a quarter of animals living in rivers, lakes and other freshwater sources are threatened with extinction, according to new research published Wednesday.

But just how many animal species have humans driven to extinction? Scientists don't have an exact answer to this question, and it's a tricky number to estimate.

Job cuts and frozen funding could inch one of the world’s rarest species even closer to extinction.

The human-driven extinction of mammals is outpacing evolution, researchers report in a study. The next 50 years may see extinctions so devastating it will take 3 million to 5 million years for the ...

"Dire wolves" created by Colossal Biosciences were pegged as "the first animals in history to be brought back from extinction." But that all depends on your definition of de-extinction — and ...

These graphics show the nearly 1,000 animals that have gone extinct over the last 500 years. You can see how there were four times as many extinctions in the 1900s than the 1800s.

A new UN report about the world's biodiversity found that up to 1 million species face extinction. Here's a breakdown of what could disappear.

But just how many animal species have humans driven to extinction? Scientists don't have an exact answer to this question, and it's a tricky number to estimate.