December 9, 2009 > TechKnow Talk: Animal Intelligence: The Brain of the Beast
TechKnow Talk: Animal Intelligence: The Brain of the Beast
When you tell your dog it's time for a walk, does it really understand the words you use? When it licks you in greeting, is it truly an expression of love? When you scold it for misbehaving, does it feel shame? And what about the often-debated question: which are smarter, cats or dogs?
Animal intelligence, often called animal cognition, is a vexingly difficult concept for us human animals. A hundred years ago, many scientists adhered to a "scala naturae," ranking animal species from most to least intelligent, with humans setting the gold standard at the top of the list.
But research over the last 50 years has shown that such a ranking doesn't make much sense. Each species is well-adapted to its ecological niche and has developed appropriate reasoning, recognition, and communication skills to survive in its specific environment. A fair comparison of intelligence between dolphins and elephants is more complicated than simply measuring how similar their behaviors are to humans.
Yet if we base our evaluation solely on the ability to survive, bacteria and cockroaches would score better than many other species. Most of us would agree these are not creatures that leap to mind when we think of intelligent animals. What if humans were tested in our ability to navigate through a dark cave or to detect the scent of a predator from a quarter mile away? Bats and deer, respectively, would make us look quite stupid.
So what is intelligence, if not merely the skills required for survival, and how can we distinguish it from instinctual or reflexive behavior? Until a dolphin composes a symphony or a monkey builds a spaceship, we have little choice but to look for those traits at which humans excel and which seem to set us apart from other, presumably less intelligent, animals, even though this approach probably favors the more social species.
Candidate attributes of intelligence include the ability to sort items into categories by color, shape, texture, etc. Memory is often cited as a component of intelligence, such as the ability to navigate through a complex landscape and recall the path taken (think of rats in a maze).
The use of tools is a candidate. Another is the ability to solve problems, to apply lessons learned from one situation or set of circumstances to another. Many researchers believe the use of language to communicate is an important indicator of intelligence within a species, as is the capacity for self awareness and emotion. Yet another measure may be mastery of simple arithmetic, such as the ability to count.
Some of these are difficult to measure, especially from our biased human perspective. Dolphins sometimes care for and protect a wounded individual. Does this indicate compassion? Nevertheless, many animal species are clearly superior to others in specific intelligence indicators.
Chimpanzees and other primates are skilled problem solvers. Some also make and use simple tools. Many primate species also perform well in language tests, with the capacity to learn and use hundreds of words.
Many birds use tools, such as sticks inserted into tree trunks to extract insects. If a suitably-shaped stick is not available, some birds will fashion one from available materials. In addition, tropical birds do well in categorizing by color and shape. After all, they must be able to recognize a ripe, edible fruit.
Rodents are excellent problem solvers. Prairie dogs also utilize a rich vocabulary to communicate the presence of predators and non-predator intruders, distinguishing between species, size, location, rate of movement, etc. Recent research indicates they utilize more than 200 "words." Dolphins and whales recognize themselves in a mirror, and will use it to groom themselves just as we do, a clear indication of self-awareness.
Surprisingly, octopi are very good at memorization, though the survival value of a keen memory for an octopus is unclear. It is perhaps not as surprising that some birds that store nuts for the winter can remember more than 1000 such locations, even after the landscape has transformed from summer foliage to winter snow.
Overall, chimpanzees, monkeys, dolphins, and whales exhibit more human-like intelligence than other mammals. Rodents, elephants, cats, and dogs also seem to be brighter than most. And some bird species, specifically parrots, owls, jays, crows, and ravens, are remarkably clever, impressing human researchers with their memories, categorization skills, and even language abilities.
Apart from behavioral evidence, are there also clues in the physical characteristics of the brain that can indicate intelligence? It turns out there is nothing very special about the brain of humans or the other animals listed above, in terms of size or general construction. Humans do possess one unique region of brain, called Broca's area. This is thought to account for our highly-developed language skills, which far outstrip those of any other species.
Humans and some of the other intelligent mammals also have a particularly high density of neurons in the parts of the brain associated with logical thought and planning. Not only are these brain cells packed more closely together than those of other animals, but the insulating sheathing around them is thicker in the brains of humans and other primates than in non-primate species. This allows nerve impulses to travel faster. In other words, our brains probably process information more quickly.
Finally, let's return to the question of cats and dogs. Dogs do quite well in most animal intelligence tests. For example, they are the only non-human species that innately understands a pointing gesture. But there is a tremendous variability of intelligence within dog breeds. Border collies consistently top the list of extremely bright dogs.
However, we should be cautious interpreting these high scores. Dogs occupy a unique relationship with us. Likely descended from wolves, they have lived with humans for more than 10,000 years, their survival dependant on their ability to please and be useful to us.
Has this long association made the dog more intelligent? Perhaps it is more accurate to say it has resulted in an animal very well suited for living among people. Dogs have become exceptionally skilled at interpreting our postures, gestures, and tone of voice, and responding appropriately.
Humans are sometimes less adept at interpreting our dogs' behaviors than vice versa. For example, a dog that licks our mouth when we return home may not be dispensing affection, but rather engaging in a wolf behavior intended to determine if the returning pack member has recently eaten.
And the tail-down, slinking posture dogs often adopt when scolded signals submission, and is triggered by the displeasure expressed in the human's voice, independent of any prior action by the dog. There is no compelling evidence that any non-human species shares our sense of right and wrong, with the attendant emotions of guilt and shame.
Cats, while smarter than many other mammals, do not perform as well as dogs in intelligence tests. Again, this should be considered in light of the innate personality of the species. Cat owners are well aware their feline friends tend to be self-centered and are often indifferent to human coaxing. Are cats less intelligent, or merely deficient in their desire to please us?
One thing is certain: both cats and dogs are intelligent enough to expertly manipulate their human keepers into providing food, shelter, protection, and ample amounts of affection. Perhaps humans aren't the gold standard for intelligence after all!