The prophet Jeremiah pondered the question of whether a leopard could change its spots. Mr. Fox asks something of the same question as he thinks about his own life: "Who am I? How can a fox be happy without a chicken in his teeth?"

You see, Mr. Fox has been out of the bird-stealing business for twelve fox years. At the beginning of the film, he and Mrs. Fox are making a raid on a chicken coop, but are caught in a trap. After telling him she is pregnant, Mrs. Fox makes him promise that if they live through this he'll find another line of work. So he becomes a newspaper columnist. But he's just not satisfied with his life—living in a hole in the ground, being poor. When he decides to move up to living in a tree, he sees from that location the farms of Messrs. Boggis, Bunce, and Bean—three greedy and mean farmers. Mr. Fox can't seem to overcome his nature as a fox and plans to raid all three of these heavily-guarded farms in one last big caper. After he succeeds, the farmers come after him, upsetting the whole animal community. It becomes an all-out war.

What makes the storytelling of Mr. Fox interesting is the dichotomy between the anthropomorphism of the characters and their animal natures. All of the animals dress in human clothing, walk on two legs, speak English, and act in human ways—most of the time. There are other times (especially when they eat) that they are very much wild animals. What are we to make of these characters? Are they people or are they animals? That is really the crux of the film—what role does our very nature play in how we act?

This issue is emphasized by the subplot involving Mr. Fox's son Ash and nephew Kristofferson. Ash longs to be as athletic as his father, but it's not to be. Kristofferson, on the other hand, is a "natural." Everything he does he does well. When Mr. Fox needs help in the raids, he doesn't ask Ash to help—who would be eager to join in—but asks Kristofferson, who has qualms about stealing. Which really represents their true nature as foxes?

The other animals—badgers, an opossum, rats, weasels—also have human characteristics, but in order to beat the humans they must rely on their animal natures, each with its own particular gift.

And then there are the humans in the story: greedy, vengeful, violent, and destructive. They will dig up or blow up the whole hill to get Mr. Fox. They care about nothing other than themselves and satisfying their own appetites and giving free range to their rage. In spite of their appearance, they more frequently act out an animal nature.

So what does it mean to be human? What is our "nature?" We identify more with the animals in this film than we do with the humans. The animals may act selfishly or virtuously. They may be loving and caring for family and friends. They may have insecurities and fears. Much like we do. But then, just as we begin to think of the animals as people, their animal nature is highlighted and we have to stop and reconsider our perspective. Perhaps what we learn is that we too are at our core wild animals. But just as in this story the animals act in ways that rise above their base animal natures, being "human" may mean that we also need to transcend our animal nature for a more noble existence.

Can a leopard change its spots? Can we change who we are, or are we only animals like all the others? The creation story in the first chapter of Genesis tells us that humankind is created in the image of God. There is the nature we should aspire to.