 Amy Dickman is a professor of wildlife conservation at the University of Oxford. She describes what makes these particular elephants special. Many of your listeners would have seen of some amazing elephant, as you say, the tusks sweeping the ground in front of Kilimanjaro. So very big tusks, they tend to touch the ground often, and they're just that most iconic looking of elephants that people might think of for sort of a tourism safari. How did this population become differentiated so that they do have these big tusks?