What Killed 60,000 Antelope in 4 Days?

Researchers are just now starting to find clues as to how more than half of Kazakhstan's herd died so rapidly.

September 4, 2015
9:40 AM EDT
In May 2015, nearly half of all the saigas, a critically endangered antelope that roams the steppe of Kazakhstan, died off. Exactly why is still a mystery. | Albert Salemgareyev