IN MARCH 2006, I had dinner with Dale Peterson. Dale was eager to tell me about his ideas for a new book about the moral lives of nonhuman animals (hereafter, “animals”). The result, The Moral Lives of Animals, is an original, wide-ranging, and ambitious book. It nicely summarizes the burgeoning knowledge about the many animals who make deliberate choices to cooperate with one another, to care for one another, and to put others before themselves. Dogs and many other animals play cooperatively and fairly by obeying agreed-upon rules of social conduct that do not permit cheating or harming their playmate, while elephants help others in need by guarding or feeding them, and rats and monkeys won’t eat if others are shocked when they do. Many animals display fairness, cooperation, compassion, generosity, justice, and empathy. Among young coyotes, individuals who don’t play by the rules often wind up living alone and suffer higher mortality rates than individuals living in packs. There’s a price to pay for violating social norms.

By tracing evolutionary continuity, Peterson shows how morality can be understood as a gift of biological evolution — one that is not limited to humans. He offers a simple functional aim of morality: “to negotiate the inherent serious conflict between self and others.” Moral behavior isn’t the same as niceness and doesn’t necessarily promote egalitarianism, but it allows for the development and maintenance of harmonious relationships in social groups and the survival of individuals and the groups within which they live. Across diverse species, injurious conflicts can arise over food, mates, and territory, and animals negotiate these interactions to minimize harm.

Peterson’s diverse background leads him toward a refreshing perspective on animal moral behavior. He anchors his arguments in Herman Melville’s classic Moby Dick. Captain Ahab, who lost a leg to the albino whale named Moby Dick, and his first mate, Starbuck, have different perspectives on the moral lives of whales. Ahab believes Moby Dick is “alive, aware, and morally responsible” and vows revenge. Ahab assumes what Peterson calls the First Way of thinking about animals, a “medieval vision of animal minds as intelligent entities constructed in a humanoid form — essentially underendowed human minds.” Starbuck adopts the Second Way of thinking: he believes animals act from blind instinct and are not morally responsible for what they do. The Second Way of thinking is the Enlightenment vision often associated with French philosopher René Descartes, according to which only humans have minds and feel pain. Peterson argues both men are wrong. He cleverly triangulates these views into a Third Way of thinking that allows for the existence of animal minds while recognizing they are alien from human minds. “Alien” doesn’t mean lesser, just “imperfectly comprehensible.” Humans are not above and apart from other animals. Our minds are adapted to work for our survival just as the unique and highly developed traits of other animals have served their own chances for survival.

Peterson’s book offers a wealth of ideas for future research and debate, including for studies of animals in the wild. For example, do highly social animals show more nuanced or complex moral behavior than less social species? What is the taxonomic distribution of moral behavior? Is it limited to mammals and a few birds or does it extend to other taxa? By answering these questions we’ll get a better handle on the evolution of moral behavior as a function of the complexity of individual social relationships, as well as more of an appreciation for patterns of continuity among different species.

Through his inquiry, Peterson envisions an increased importance for empathy that will serve both nonhuman and human animals, and he hopes in the future we will move toward “greater tolerance, higher wisdom, and a new condition of peace between humans and nonhumans alike.” Animals are more peaceful, more generous, and fairer than we give them credit for, and can be excellent teachers if we allow them to be. They can show us how to have compassion and empathy for one another and how and why our troubled and wounded world will benefit greatly from these lessons in coexistence.