We often regard our animals as part of the family--beloved children and steadfast best friends wrapped in one (more often than not) cuddly package. The empathy and love pet owners develop for their creature companions is not a one-way street, however. Animals also experience rich emotional lives.

As scientists reveal more about the inner workings of every kind of creature, from dogs to fish, authors are responding with nonfiction books that convey these latest findings. At the same time, a growing body of fictional work explores what it may be like to occupy the mind of a cat, camel or chimp--helping not only to elucidate what it is to love an animal and be loved in return but also to reveal truths about what it is to be human.

"One of the central goals of writing about this stuff is to enrich and elevate our appreciation of animals," says biologist Jonathan Blacombe, author of What a Fish Knows"Science and literature are powerful tools for opening eyes and making people realize that animals are not so different from us after all."

Rational emotions

Emotions in nonhuman animals are by no means a new development. They likely evolved alongside consciousness as an "extremely useful" evolutionary adaptation, says Blacombe. "If you have to stop and think about how to react to a scary stimulus, you lose precious time," he explains. "Whereas if the flight-or-fight response kicks in emotionally, you're out of there and then you survive and pass on genes for that response to your offspring."

The same advantage applies to the feeling that we describe as love: Both humans and dogs, for example, experience strong emotional connections to our relatives and those around us. Evolutionarily speaking, we care for them and protect them--and they do the same for us--because such behaviors ultimately increase our chances of passing on our genes. Long ago, our two species intersected and likewise developed a shared, beneficial relationship: Dogs protected us, and we fed them. But what began as a utilitarian relationship between dogs and people soon developed into something deeper. Thousands of years later, we're still going strong.

It wasn't until recently, however, that most people took the time to consider animal emotions (Charles Darwin being an early exception--he wrote a whole book on the subject). Now, though, scientists know that it's not just humans and other mammals closely related to us who experience things such as fear, lust, and attachment. A whole spate of creatures--including reptiles, amphibians, and even fish--do, too. Sometimes, those emotions are stunningly similar to our own: Bereft baboon mothers who have lost a child exhibit the same grieving hormones and behavioral changes as human mothers, and MRI scans of dogs reveal higher brain activity when presented with a photo of their favorite human versus a stranger or mere acquaintance.

A number of excellent books have been published to help lay readers navigate this quickly expanding field. Jeffrey Moussaieff Masson and Susan McCarthy's When Elephants Weep explores the emotional lives of the animal kingdom; Peter Wohlleben's The Inner Life of Animals delves into nonhuman cognition and emotion; Marc Bekoff's Wild Justice considers the moral lives of animals; Barbara J. King's How Animals Grieve gives an overview of different species' experience of grief; and Carl Safina's Beyond Words: What Animals Think and Feel uses real-world evidence and neuroscience  to describe animals' unique personalities.

"There's been a big increase in the number of books about the inner lives of animals, and how they feel, to the point that there's too many to list," says Blacombe. "One reason is because science has started asking questions about animals that it wasn't in the 20th century, and because our moral concern and consideration for animals has grown."

Through their eyes

Animals have long featured in fiction, from the revolutionary menagerie in George Orwell's Animal Farm to the trials and tribulations of an extended family of rabbits in Richard Adams' Watership Down, to the ever-so-loyal and loving Bailey in W. Bruce Cameron's A Dog's Purpose.

"We make books and stories and films about animals over and over again for a reason--because we know something is there," says Susan McHugh, a professor of English at the University of New England and author of Animal Stories: Narrating Across Species Lines. "Fiction and nonfiction tries to represent that."

Animals' presence, especially if told in the first person, can shed light on what it is to truly love. "We set bars for the people around us--'You need to act a certain way for me to be happy,'or 'You did this and therefore you made me do that'--and yet we don't do that for our dogs," says author Garth Stein. "I think our relationship with our dogs is the very definition of unconditional love."

Authors also turn to animals to provide fresh commentary on our own species. Stein's The Art of Racing in the Rainfor example, is a firsthand account of a dog who believes he will be reincarnated as a person, so he studies the human world in the hope of excelling at it when he comes back. "The idea of having a dog be a sort of spy, if you will--an observer of human behavior--is something that struck a chord," he says. "Fiction allows us to see things from a different perspective."