At what age is a dog the smartest?

The canine IQ test results are in: Even the average dog has the mental abilities of a 2-year-old child.

The finding is based on a language development test, revealing average dogs can learn 165 words (similar to a 2-year-old child), including signals and gestures, and dogs in the top 20 percent in intelligence can learn 250 words.

And the smartest?

Border collies, poodles, and German shepherds, in that order, says Stanley Coren, a canine expert and professor emeritus at the University of British Columbia. Those breeds have been created recently compared with other dog breeds and may be smarter in part because we've trained and bred them to be so, Coren said. The dogs at the top of the pack are on par with a 2.5-year-old.

Better at math and socializing

While dogs ranked with the 2-year-olds in language, they would trump a 3- or 4-year-old in basic arithmetic, Coren found. In terms of social smarts, our drooling furballs fare even better.

"The social life of dogs is much more complex, much more like human teenagers at that stage, interested in who is moving up in the pack and who is sleeping with who and that sort of thing," Coren told LiveScience.

Coren, who has written more than a half-dozen books on dogs and dog behavior, will present an overview of various studies on dog smarts at the American Psychological Association's annual meeting in Toronto.

"We all want insight into how our furry companions think, and we want to understand the silly, quirky and apparently irrational behaviors [that] Lassie or Rover demonstrate," Coren said. "Their stunning flashes of brilliance and creativity are reminders that they may not be Einsteins but are sure closer to humans than we thought."

Math test

To get inside the noggin of man's best friend, scientists are modifying tests for dogs that were originally developed to measure skills in children.

Here's one: In an arithmetic test, dogs watch as one treat and then another treat are lowered down behind a screen. When the screen gets lifted, the dogs, if they get arithmetic (1+1=2), will expect to see two treats. (For toddlers, other objects would be used.)

But say the scientist swipes one of the treats, or adds another so the end result is one, or three treats, respectively. "Now we're giving him the wrong equation which is 1+1=1, or 1+1=3," Coren said. Sure enough, studies show the dogs get it. "The dog acts surprised and stares at it for a longer period of time, just like a human kid would," he said.

These studies suggest dogs have a basic understanding of arithmetic, and they can count to four or five.

Basic emotions

Other studies Coren notes have found that dogs show spatial problem-solving skills. For instance, they can locate valued items, such as treats, find better routes in the environment, such as the fastest way to a favorite chair, and figure out how to operate latches and simple machines.

Like human toddlers, dogs also show some basic emotions, such as happiness, anger and disgust. But more complex emotions, such as guilt, are not in a dog's toolbox. (What humans once thought was guilt was found to be doggy fear, Coren noted.)

And while dogs know whether they're being treated fairly, they don't grasp the concept of equity. Coren recalls a study in which dogs get a treat for "giving a paw."

When one dog gets a treat and the other doesn't, the unrewarded dog stops performing the trick and avoids making eye contact with the trainer. But if one dog, say, gets rewarded with a juicy steak while the other snags a measly piece of bread, on average the dogs don't care about the inequality of the treats.

Top dogs

To find out which dogs had the top school smarts, Coren collected data from more than 200 dog obedience judges from the United States and Canada.

He found the top dogs, in order of their doggy IQ are:

1. Border collies
2. Poodles
3. German shepherds
4. Golden retrievers
5. Dobermans
6. Shetland sheepdogs
7. Labrador retrievers

At the bottom of the intelligence barrel, Coren would include many of the hounds, such as the bassett hound and the Afghan hound, along with the bulldog, beagle and basenji (a hunting dog).

"It's important to note that these breeds which don't do as well tend to be considerably older breeds," he said. "They were developed when the task of a hound was to find something by smell or sight." These dogs might fare better on tests of so-called instinctive intelligence, which measure how well dogs do what they are bred to do.

"The dogs that are the brightest dogs in terms of school learning ability tend to be the dogs that are much more recently developed," Coren said. He added that there's a "high probability that we've been breeding dogs so they're more responsive to human beings and human signals." So the most recently bred dogs would be more human-friendly and rank higher on school smarts.

Many of these smarty-pants are also the most popular pets. "We like dogs that understand us," Coren said.

We also love the beagle, which made it to the top 10 list of most popular dog breeds in 2008 by the American Kennel Club. That's because they are so sweet and socialable, Coren said. "Sometimes people love the dumb blonde," Coren said.

And sometimes the dim-wits make better pets. While a smart dog will figure out everything you want it to know, your super pet will also learn everything it can get away with, Coren warns.

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Dolphins are as smart as 3-year olds, and dogs as smart as two-year old children, and some chimps are better at remembering things than any adult I know. But what do intelligence comparisons actually show us?

On the surface, human babies appear to be miles behind the rest of the animal kingdom. After all, foals can get up and gallop in the first minute of life. Whale calves can instantly swim with their pod. But human babies can’t do much at the start of life.

One reason human infants are so behind the curve is that our gigantic brains have to make it out of our moms’ pelvises (which aren’t terribly large because we walk on two legs). In order for a baby human to come out with the brain development of a baby chimp, we’d have to gestate for 18-21 months, writes zoologist Adolf Portmann.

When it comes to comparing dogs and babies, Stanley Coren, a biologist at the University of British Columbia, has crunched the numbers for years. He estimates that dogs have a similar intelligence to a 2.5-year old child. That benchmark comes from a couple of different tests.

First off, Coren looked at verbal comprehension for babies and dogs. He found that the average dog can understand about 165 words, including signs and signals – about the equivalent of a 2-year old baby. Canine high-achievers, on the other hand, can understand about 250 words — equivalent to a 2.5-year old baby.

Coren points out that dogs never pass the mirror test – they’re not able to comprehend a reflection in the mirror. Human babies start to pass this test around 18 months, though Coren says the average is 3 years.

When it comes to social understanding, dogs are even more advanced – equivalent to a human adolescent. Dogs are very savvy about “who’s moving up or down the social ladder, and who is sleeping with whom,” Coren told KinderLab.

Not everyone agrees that gauging infants and animals is a helpful thing to do. Alexandra Horowitz, a psychologist at Barnard College, says that the comparison both overstates and understates dogs – and babies. “The dog is very good at doing dog-things, and the child is developing a talent for doing human-things,” Horowitz told KinderLab.

“When, around 2, my son become highly verbal, it’s true that the divergence between the dog and child increases. But my dogs still knew things that my son did not. And my dogs may still be better readers of my intent, in some arenas, than my son is. Apart from which, they know a lot about smell,” Horowitz says.

But what if a universal intelligence test could even the playing field for animals, humans and machines? Two computer scientists, José Hernández-Orallo of the Polytechnic University of Valencia, in Spain, and David Dowe of Monash University, in Australia, are working on a test that wouldn’t rely on language and could assess intelligence in groups of animals (like a swarm of ants working collectively). The issue, says Dowe, is that the interface has to work for all types of creatures and machines.

Coren says he hopes that people do treat dogs differently when they read about their mental abilities. “You begin to find all these parallels” when discovering how best to work with babies and dogs, he says. “The same kind of advice that people learn about kids will work with dogs, if you treat a dog like a toddler.”