Helen Macdonald's book "H is for Hawk" turned her goshawk Mabel into one of the most memorable literary characters of recent years. Mabel is no longer with her, but Helen now has a new avian companion — an ornery and very smart parrot.
What separates your mind from an animal's? It's a question we've all asked, but renowned primatologist Frans de Waal says there's no point trying to rank who's smarter or dumber in the animal world. In fact, he believes there's no clear dividing line between humans and the rest of the animal world.