It’s a mystery on a global scale: five times in Earth’s past, life has been nearly extinguished, the vast majority of plants and animals annihilated in a geologic instant. What triggered these dramatic events? And what might they tell us about the fate of our world? The program joins scientists around the globe in search of answers to two of the most dramatic mass extinctions: the “K/T Extinction,” which wiped out the dinosaurs, and “The Great Dying,” which 250 million years ago annihilated nearly 90% of all Earth’s species. These early mass extinctions could hold clues for what may be happening today.