Please, take a listen: audio clip
Today it's really difficult for us to evaluate whether a particular fossil species is the ancestor of another one. You're always looking for the right anatomical features to link something up. In recent years, Meave Leakey, Richard's wife, has been running the Turkana field site. And today their daughter Louise is key in charge. And in 2001, Meave found a fossil skull on the west side of Lake Turkana. A fossil skull that was the same age as Australopithecus afarensis.
I'm not sure how I should understand that. Sure, to be in charge of something means to be in control of it—such as an enterprise or project. That's simple. But what I'm having real trouble with here is how the adjective key is used in conjunction with the expression in charge. If I said, "Who's key in charge here?", what would that possibly mean?