What would it be like to go inside the mind of an animal? We have all gazed into a creature's eyes and wondered: what is it thinking about? What does it really know? Now, the revolutionary science of animal cognition is revealing hard evidence about how animals understand the world around them, uncovering their remarkable problem-solving abilities and exploring the complexity of their powers of communication and even their emotions. In this mini-series, NOVA explores these breakthroughs through three iconic creatures: dogs, birds and dolphins. We'll travel into the spectacularly nuanced noses of dogs and wolves, and ask whether their reliance on different senses has shaped their evolution. We'll see through the eyes of a starling in flight and test the tool-using skills of the smartest of birds, the crow. We'll listen in as scientists track dolphins in the Caribbean and elephants on the African savannah, trying to unlock the secrets of animal communication. As we discover how researchers are pushing the animal mind to its limits, we'll uncover surprising similarities to -- and differences from -- the human mind. What makes an animal smart? Many scientists believe the secret lies in relationships. Throughout the animal kingdom, some of the cleverest creatures - including humans - seem to be those who live in complex social groups, like dolphins, elephants and apes. Could the skills required to keep track of friend and foe make animals smarter? To find out, NOVA goes inside the social lives of some of the smartest animals on the planet.