In 1961 a child psychologist proposed a radical idea to the American Psychological Association: What if dogs could help therapists connect to troubled patients? Perhaps the animals would help soothe anxiety and help people open up. When Boris Levinson of Yeshiva University presented this idea, many of his colleagues thought it was laughable. Yet the idea that humans might derive therapeutic effects from animals would go on to capture the attention of many future researchers.

In recent years scientists have started investigating our attachment to creatures great and small. Although various types of pets and non-Western cultural dynamics remain largely unexplored, research has begun to examine how the animals that surround us affect our mood and mental states. New work has, for example, revealed how just thinking of a beloved pet may help us stay calm under pressure.

Most of the research thus far has focused on dogs, a fact that is reflected in these pages. But we also present some surprising data on other pets and their owners, including information gathered from you, our readers.

Our hope in assembling these stories is to inspire readers and researchers alike to ponder recent findings and the deeper questions that they may provoke. How are we like our animal friends, and how do we differ? What makes these relationships so appealing—and what qualities lead one person to adopt a cocker spaniel and another to take in a cobra? Ultimately, if we want to understand the human mind in all its contexts, we must consider our connections not merely with one another but across the divide of species.