Art is usually considered a uniquely human ability, but that may not be true. Given the opportunity, animals like chimpanzees and gorillas and elephants produce abstract designs that arguably rise to artistic level. Arguably is, however, the key word. It's hard enough to agree on an essential definition of human art, much less an animal one. But it's a debate welcomed by Jack Ashby, manager of the Grant Museum of Zoology at University College London. "That's the question we're asking people: What is art?" said Ashby, who thinks that human art may well reflect a creativity expressed in animals' natural behavior, even if people don't always appreciate it. Ashby organized the Art by Animals exhibition, on display at the museum through March 9. On the following pages, Wired looks at possible animal art from the exhibition and elsewhere. Above:

Gorilla Painting ---------------- A painting by Samantha, a western lowland gorilla at the Erie Zoo in Pennsylvania. Image: Rob Eagle/UCL

Abstract Master This finger-painting by Bakhari, a chimpanzee at the St. Louis Zoo, is Ashby's favorite. "You'd be happy to believe that a human abstract expressionist had painted it," he said. In 2005, three paintings by a chimpanzee named Congo, the star of a mid-1950s chimpanzee art exhibition curated by the anthropologist and painter Desmond Morris, sold for nearly $20,000. Images: 1) Rob Eagle/UCL 2) A painting by Congo. (WIkimedia Commons)

Art and Instinct Many creatures construct aesthetically beautiful objects but are not considered artists -- yet, as with this honeycomb, the same object sculpted by human hands would be art. The difference: As best as we know, the bee's creation reflects a biologically predetermined set of instructions rather than intentional choices. Image: Peter Shanks/Flickr

Showing Intent To help keep them entertained, chimpanzees at the Chimp Haven sanctuary are regularly given access to painting supplies. Sanctuary staff insist that the resulting works reflect a crucial condition of art: intent. "You have to choose a tool. You have to choose your colors. If you stick your dog's paws in paint and let them run around the floor, that's not art. It's happenstance," said Chimp Haven communications director Karen Allen. "We give these chimpanzees a canvas, and they do what they're going to do. They pick their colors, they pick their tools. There's usually some sort of symmetry. There's always white space. It's really interesting to see how they do all this." Image: Amy Fultz/Chimp Haven

Elephants Painting Flowers Painting elephants are a YouTube standby and tourist favorite, but their movements are guided by their handlers. Image: A floral arrangement painted by Boon Me, an elephant at Thailand's Samutprakarn Zoo. (Rob Eagle/UCL)

Elephant Abstracts Even if figural paintings by elephants don't truly reflect artistic impulses, they're almost certainly intelligent enough to have one. Image: An abstract by Nong Bank, an elephant at Thailand's Samutprakarn Zoo. (Rob Eagle/UCL)

Orangutan Paintings "There's definitely a question: What is creativity?" said Ashby. "We don't know where that comes from in humans, either." Images: 1) A painting by Baka, a Sumatran orangutan at the Cheyenne Mountain Zoo. (Rob Eagle/UCL) 2) A painting by Joseph, a Sumatran orangutan at the Erie Zoo. (Rob Eagle/UCL)

Bird Nest Messages Though birds' nests are often complex and ornate, they're not considered art, perhaps because they're considered to be both utilitarian and instinctive. Art and utility are certainly not incompatible, however, and some nest designs reflect a communicative intent. These black kite nests, for example, use white plastic adornments as territorial code. Image: Fabrizio Sergio.

Courtship Display as Art In animals as in people, courtship is a great inspiration, and a likely place to look for artistic inclination. Male bowerbirds, for example, build complicated structures called gessos to impress prospective mates. "They decorate them with piles of one-color things: little flowers, blue beetles' wing cases, green fruit," said Ashby. "The only purpose is to attract the mate, but it's obviously very aesthetic." Image: L.A. Kelley/Science