Their plumage can be beautiful, and many warble or sing. A few even seem kind of clever, in their way. But for all that is impressive about birds, most people would agree: "Brainy" they are not.
Now science is about to set the record straight. And the truth may be jarring for all those big-brained mammals for whom the very word for avian gray matter has come to mean "dummy."
Today an international group of experts is publishing a call for scientists around the world to switch to a new set of words to describe the various parts of the avian brain -- a wholesale revision of terms that is rarely seen in science and the first total makeover of bird brain anatomy in more than a century.
The new system, which draws upon many of the words used to describe the human brain and has broad support among scientists, acknowledges the now overwhelming evidence that avian and mammalian brains are remarkably similar -- a fact that explains why many kinds of bird are not just twitchily resourceful but able to design and manufacture tools, solve mathematical problems and, in many cases, use language in ways that even chimpanzees and other primates cannot.
In particular, it reflects a new recognition that the bulk of a bird's brain is not, as scientists once thought, mere "basal ganglia" -- the part of the brain that simply coordinates instincts. Rather, fully 75 percent of a bird's brain is an intricately wired mass that processes information in much the same way as the vaunted human cerebral cortex.
Accordingly, under the new system, no longer will a part of that avian cortex-like region be referred to as the "archistriatum," with its Latin root that implies primitive. As of today it is the "arcopallium," which means, in effect, "arched structure in a cognitively sophisticated area."
"It's the opposite of sticks and stones -- names do matter when it comes to how scientists and other people think about things," said Duke University neuroscientist Erich Jarvis, a leader of the Avian Brain Nomenclature Consortium, whose manifesto appears in the February issue of the journal Nature Reviews Neuroscience.
The old system, Jarvis said, stunted scientists' imaginations when it came to appreciating birds' brainpower. The new system revamps about 95 percent of the 1,000 or so terms that scientists use to describe avian brain structure.
"It's long overdue," said Evan Balaban, a behavioral neuroscientist at McGill University in Montreal. "Changing a name by itself may not seem earth-shattering, but it reflects an important change in knowledge."
The problem goes back to the 19th century, when German naturalist Ludwig Edinger did the first careful studies of avian neuroanatomy and labeled the myriad parts of the bird brain. He had a good eye for detail, Jarvis said. But he was trapped in the political and religious thinking of his day, which presumed that evolution is a process that goes from simplest to more complicated and from dumber to smarter, all culminating in the appearance of humans, who were seen as closest to God.
In keeping with that view, Edinger's naming system relied heavily on prefixes such as "paleo" and "archi" to indicate the primordial nature of the bird's brain. Similar structures can be found near the core of "higher" animals' brains -- leftovers, it was believed, from evolutionary history. But they were covered by what were believed to be newer layers of smarter material such as the human "neocortex."
Edinger was unaware that the first birds did not appear on Earth until 50 million to 100 million years after the earliest, supposedly "neo" mammals. He also got fooled by the fact that the large portion of bird brain devoted to higher processing of visual and auditory information -- the part equivalent to the human cerebral cortex -- has a neural architecture that makes it look, at first, like the simpler regions that deal with instinctive behaviors.
Like many people today, Edinger had little reason to question the conclusion that birds had meager intellects, said Tony Reiner, a University of Tennessee neuroscientist and a member of the consortium.
"Pigeons bob their heads while they walk, which makes them look like morons, and so people assumed birds only have the moron part of the brain," Reiner said. "People thought they were stuck with just the instinct part."
In recent decades, however, several avenues of evidence have proved otherwise. Studies of brain chemicals, neural connections and genetic controls over embryonic brain development have shown that the vast bulk of a bird's admittedly small brain is not "primitive" at all but rather constitutes a robust "pallium," or higher-processing center.
And behavioral studies in recent years have proved that many birds have more pallium power than your average mammal.
Even seemingly moronic pigeons can categorize objects as "human-made" vs. "natural"; discriminate between cubistic and impressionistic styles of painting; and communicate using visual symbols on computers, according to evidence compiled by the consortium, which spent seven years on the project with input from scientists around the world.
Some birds can play games in which they intentionally tell lies. New Caledonian crows design and make tools. Scrub jays can recall events from specific times or places -- a trait once thought unique to humans. And perhaps most impressive, parrots, hummingbirds and thousands of other species of songbirds are able to teach and learn vocal communication -- the basic skill that makes human language possible. That's a variant of social intelligence not found in any mammal other than people, bats, and cetaceans such as dolphins and whales.
In recognition of such sophistication, the group deleted all prefixes, suffixes and other linguistic features that implied evolutionary precedence, superiority or inferiority. In their place the group offers value-free words that tell, for example, where a structure lies or how it is connected to other brain parts.
Irene Pepperberg, a comparative psychologist at Harvard's Radcliffe Institute for Advanced Studies whose experiments with a grey parrot named Alex have shown that some birds are capable of extremely complex thinking -- even grasping something akin to the sophisticated concept of "zero" -- said she was gratified to see scientific language catching up with reality.
"The argument has been that birds don't have a cerebral cortex so they can't do these things," she said. "Now we can appreciate that the bird does have a brain area that we can imagine doing these things. It makes all this not so incredibly surprising."