June 30,2006 -- People generally define intelligence in terms that place our own species at the apex, but recent studies on other animals suggest skills such as abstract thinking, problem solving, reasoning, and language -- once thought unique to us -- may not be so uncommon after all.
"The closer we examine animals, the more they surprise us with their intelligence and awareness," said Jonathan Balcombe, a research scientist at Physicians Committee for Responsible Medicine in Washington, DC.
"Chickens practice deception, pigeons can categorize images in photographs as quickly as we can, a gorilla plays a joke on a human teacher, and a tiny fish leaps from one tide pool to another using a mental map formed during high tide."
Balcombe did admit that in the evolutionary lottery, humans got lucky. Factors such as climate, the need for socialization, and challenges associated with foraging for intermittently available food may have contributed to our unique skill set.
Taken individually or in other combinations, though, these skills are being increasingly noticed in other creatures.
A prevailing view, which at least dates back to French philosopher Rene Descartes and was reiterated by noted behaviorist B.F. Skinner, holds that all examples of non-human intelligence are simply conditioned behaviors.
Recent studies are putting that view to rest.
For example, Ohio State University entomologists implanted electrodes into the brains of sphinx moths.
The researchers monitored the moths' nervous systems while presenting them with different odors -- including sugar water, a favorite moth treat.
"We saw a dramatic restructuring of the neural networks that convert scent into a code that the rest of the brain can understand," said lead author Kevin Daly, who concluded that, like humans, moths learn as well as act on instinct.
Key to human intelligence is our ability to think in abstract terms, and the ability to apply previously acquired concepts in problem solving.
While it is well known that some animals use tools and learn from past mistakes, the question of how much they understand about such tools and their environment has long been contentious.
A recent study on rooks suggests the crow-like birds can apply learned rules when solving problems.
Biologists at the University of Cambridge set up a "trap-tube task" consisting of a horizontal tube with a trap along its length.
To solve the puzzle, the birds had to use a tool to push a piece of food out of the tube and away from the trap. Two rules allowed the birds to obtain the food: learning how the position of the food related to the trap, and understanding how the overall task worked.
The birds aced the tests, even when trap appearance and the level of difficulty changed. The study suggests this species, and possibly all birds, possess rule abstraction. Other research has determined that baboons and chimpanzees think abstractly.
Linguists have argued that certain patterns of language organization are the exclusive province of humans. Once again, new research is turning that idea on its head.
For example, the common European starling recognizes sound patterns and distinguishes between them, according to a recent study led by Timothy Gentner, assistant professor of psychology at the University of California, San Diego.
Gentner found that whole clauses could be inserted into starling songs to create new and "grammatically correct" meanings. For humans, this would be like transforming the phrase "the bird sang" into "the bird the cat chased sang."
Whales and dolphins appear to share similar abilities. And like some birds, dolphins appear to name themselves.
Some animals may even be "bilingual," since birds appear to decipher the sophisticated vocalizations of ground squirrels.
"As humans, we suffer from cognitive myopia," Gentner told Discovery News. "We understand things from our point of view. Animals are noteworthy and miraculous, not just because they share traits with us, but because they are special and impressive in their own right."
From IQ to EQ
Another quality of human intelligence that many animals appear to share is the capacity for complex emotion.
The sensory rewards and punishments that accompany strong emotions, in many cases, create the drive for animals to stay alive and reproduce. Countless studies suggest that creatures from birds to bats to baboons feel joy, pain, sadness and other emotions.
Roughly 90 percent of all lab animals are rodents, but Balcombe said these animals are sensitive, inquisitive, playful and complex individuals.
Rat brains can be stunted, in fact, when the rodents are confined without mental enrichment. Balcombe believes mice even develop neuroses and may feel pain during testing.
"Our particular intelligence also endows us with an advanced capacity for morality," Balcombe added.
"Gradually we are coming to realize that it's wrong to make other feeling beings suffer for our own selfish interests," he said. "Might doesn't make right. If a more intelligent race arrived from outer space, would they have the right to torture and kill us? I think not!"
Crows are known for their mental sharpness. Recent studies have shown, for instance, that they can make tools and learn rules to guide their future behavior, qualities it was once thought only few animals possessed.
No Words Necessary
What's obvious to many a zoogoer has been long overlooked in science: the ability of many species to experience complex emotions.