Pablo Escobar's hippos may help counteract a legacy of extinctions

When cocaine kingpin Pablo Escobar was shot dead in 1993, the four hippos he brought to his private zoo in Colombia were left behind in a pond on his ranch. Since then, their numbers have grown to an estimated 80-100, and the giant herbivores have made their way into the country's rivers. Scientists and the public alike have viewed Escobar's hippos as invasive pests that by no rights should run wild on the South American continent.