FOUR SCIENTISTS inject a genius serum into a rat. They gather around the brown, furry creature to see the effect. Suddenly the rat quivers and falls down -- dead.
They chuck the rat out in the alley and head back to the lab to start over. Moments later, the rat shakes itself off and runs away.
Now that's a genius.
Animal behaviorists love this story because the last laugh is on the scientists who tried to measure brain power. We tend to judge animals by how they perform for us. But is that fair?
Is a Scottish terrier smarter than a tabby cat because it can fetch a tennis ball? Or is the cat smarter because its response is, "Get it yourself, dope."
Elephants are considered bright partly because they use sticks as tools; likewise, sea otters use stones to crack open abalone shells. A chimpanzee figures out that by piling boxes, it can reach a banana high on a shelf. Navy-trained dolphins can detect underwater mines and perform other military tasks.
Brain size, circus tricks and vocabulary are just a few possible tools to measure animal intelligence. But scientists and animal trainers don't agree on which tools are true measurements of intelligence, much less whether human beings even have the proper perspective or right to ask how smart animals are.
"It's just a can of worms. All of us are going to agree that a rhesus monkey is more intelligent than a guinea pig," said Benjamin Hart, a professor of physiology and behavior at the University of California, Davis, School of Veterinary Medicine.
The problems begin when you try to compare animals closer on the evolutionary scale, Hart said.
Brain size and fast learning -- that's what defines a smart animal, says Edward O. Wilson, a professor of science at Harvard University's Museum of Comparative Zoology.
By that standard, apes come out on top. No. 1, according to Wilson, is the chimpanzee, followed by the gorilla, orangutan, baboon, gibbon and monkey. Then the smaller-tooth whale, the dolphin, elephant and the pig.
Everybody agrees the pig is the prodigy of the farm.
"George Orwell had it right when he put them in charge of the barnyard" in the book "Animal Farm," one behaviorist said. Miniature pet pigs are supposed to be just as smart.
Not counting pigs, dogs are probably our smartest pet, Wilson said.
Dogs' brains are larger than those of cats, and they are better problem solvers, he said. Wilson doesn't buy the argument that cats are smarter because they "refuse" to learn tricks.
After the dog, he would rank the cat and the most-intelligent birds (parrots and crows, for instance) as a tie. Then the rabbit, followed by the snake. "They're stupid . . . and fish are right down there with snakes," Wilson said.
"I hope this doesn't bring calumny and fire on my head," he added.
But ranking animals by intelligence does rankle some people and can even heat up charges of "species-ism."
We may "ooh" and "aah" at the circus, but Michael Fox, a syndicated columnist and vice president of the Humane Society of the United States, said you can't call an animal smart just because it learns what humans teach it.
"What people think of as intelligence they confuse with trainability. Trainability is more related to dependence than intelligence," Fox said.
Sometimes dependence suits human purposes better than intelligence.
Guide dogs, for instance, are respected for their ability to lead their owners to a bus stop or stop at red lights. But the smartest dog in the kennel isn't necessarily the best guide dog.
"A dog that is too darned smart for its own good cares only about himself. We prefer a dog that wants to please you first," said Peter O'Reilly, training supervisor for Guide Dogs for the Blind Inc. in San Rafael. "Stupid dogs can be really good guide dogs as long as they have the will to listen to you. It just takes more repetition."
Dog breeds provide a good example of how man has selectively bred animals -- sometimes for intelligence, and in other cases, at the expense of intelligence.
Animal behaviorist Nicholar Dodman at the Tufts University School of Veterinary Medicine said selective breeding has made the Irish setter, for instance, "a bit woolly headed."
"You take a collection of genes, and you manipulate them over several generations to be something that you want," Dodman said. "When you're breeding the Irish setter, you're looking for an ideal standard of long legs, not intelligence."
On the other hand, Dodman said, "The border collie is a rocket scientist -- they're just so smart. They were trained to chase sheep."
Hart, co-author of "The Perfect Puppy" (W.H. Freeman & Co., 1988), said research has shown that no dog scores consistently enough in intelligence tests to stake a claim to brainiest -- despite the reputations of poodles and German shepherds as intelligent.
Animal behaviorist Warren Eckstein insists that the cat ties the dog as smartest household pet. Eckstein wrote "How to Get Your Cat to Do What You Want."
"I've seen cats outsmart human beings plenty of times," Eckstein writes in his book.
The smartest birds, such as African gray parrots, can match the intellect of a gifted 5-year-old child, but emotionally they measure up to a 2-year-old, said avian-behavior consultant Chris Davis of Sierra Madre.
Davis describes one bird who was brighter than her owner believed. The owner insisted her young bird's talking was just babbling, not communicating -- until she put the parrot in a new cage.
"No like," the bird told her. When her owner ignored her, the parrot hopped up and down and screamed, "NO LIKE! NO LIKE!" In the wild, the bird would be squawking warnings and chattering to other parrots. But in captivity, she learned to communicate her wishes with a species she'd never even see in her own environment.