Tallulah the Wonder Cat plays fetch, and can figure out that she has to go to the other room when she bats the toy under a door—a sure sign of abstract reasoning. The Magnificent Valentino leaps into my arms after my shower to luxuriate in the hot, steamy towel. He never jumps up unless invited. But does my cats' behavior indicate intelligence, or are they simply automatons?

Science, philosophy and religion have long pondered the difference between humans and animals. Depending on the time and the part of the world, humans revered animals as gods, relegated them to sub-human slave status or honored them as souls in transition. Most recently, though, human cognitive ability coupled with self-awareness has captured Western scientific theory. Humans are the only animals capable of higher reasoning—we invent things and use tools—and our unique self-awareness allows for a search for meaning, something other animals can't begin to grasp.

Or can they? Just how big is the gap between human and animal intelligence, really?

Virginia Morrell, in "Minds of Their Own," published in the March issue of National Geographic, set out to answer that question. She found an eclectic mix of animals—from octopus to crows, rodents, dogs and apes—with surprising mental abilities. "We're glimpsing intelligence throughout the animal kingdom, which is what we should expect," says Clive Wynne of the University of Florida in the piece. Wynne has studied cognition in pigeons and marsupials. "It's a bush, not a single-trunk tree with a line leading only to us."

In addition to humans, Morrell finds that dolphins, apes and elephants are all self-aware, recognizing their own reflections as themselves. Researchers have found the ability to deceive and strategize, once thought of as uniquely human, in fish, birds and apes, and have demonstrated that some species even understand the abstract concepts of past and future. Morrell met a parrot who understood the concept of zero, and a particularly precocious Viennese border collie named Betsy who understands upward of 340 words, rivaling great apes, and knows 15 people by name.

The Smithsonian National Zoological Park in Washington, D.C., has several research projects dedicated to discovering how animals think. Chimpanzees and orangutans, scientists discovered, can learn concepts such as "less" and "more," can count and learn to substitute symbols for objects. The park's Think Tank exhibit displays many different types of animal intelligence, from the complex social hierarchies of insects to macaque innovation and orangutan language skills.

Ultimately, science may yet prove that animals possess many "human" intelligence traits. Or perhaps the opposite is true: Humans think more like animals than we care to admit.

Maybe there's a third option: Animals, including humans, all have unique gifts of intelligence, many of which are undiscovered. Maybe animals have as much to teach us as they do to learn.