For some of the loneliest animals on the planet, captive breeding programs and human intervention may the only hope.

Leopards have been hunted to extinction in some areas, and their habitat is under pressure from growing human populations.

The Bible makes reference to more than 100 species, metaphorically and literally. But many of those creatures are now gone from the Holy Land, or on the verge of extinction there.

In 1883, biologists believed the world had lost one of its zebra species. Now, more than 100 years later, researchers are on the verge of bringing the Quagga back to life.