For the Love of a Dog (22 page)

Some dogs take this to extremes—Bo Peep barked for two days when I moved the farm truck from the
right
side of the barn to the
left
—but at normal levels caution is useful. It keeps wild animals safe more often than not, and so it tends to be a trait that hangs around in the gene pool. No wonder then, that the tendency to be fearful around unfamiliar animals and objects, often called “shyness” by biologists, has a high degree of heritability in dogs, as well as in people.

Lots of people are surprised that their dog’s fears of strangers can, at least in part, be explained by inheritance. Behaviorists and trainers hear, almost on a daily basis, that a client’s dog must have been abused, because she reacts so fearfully to strangers. However, many of these dogs are just shy, and they aren’t any more comfortable around unfamiliar strangers than shy people are. Shyness exemplifies one of the many ways that genetics and brain function can influence how a dog experiences fear. This seems to be a concept to which we’re resistant, although we have no problem associating other traits, like artistic talent or the gift of gab, with an individual’s genetic inheritance. We all seem happy to accept that physical characteristics like eye color, coat color, and size are inherited, and that genetics influence certain types of canine behavior, such as retrieving and herding. It turns out that genes also influence how fearful or reactive dogs are, so part of how your dog behaves to visitors was already hardwired within her when you brought her home as a pup.

We’re starting to understand a lot about how genes affect fearful behavior. One of the greatest influences of our genetic heritage is on which parts of our brains are most easily activated. We know that different versions of genes, the architects that draw the blueprints of our body, create different activity levels in the amygdala and other fear-related areas of the brain. For example, a study in 2002 found that one of the genes that help regulate levels of serotonin in the brain comes in two different versions. One version, interacting with certain experiences during early development, leads to too much serotonin, a neurotransmitter that in normal amounts helps to soothe and calm the activity of the amygdala. But more isn’t always good, and too much serotonin sends the amygdala into overdrive. Overwhelmed with too much serotonin, the amygdala overreacts, creating a high incidence of anxiety disorders.

More evidence about the influence of genetics on fearful behavior comes from a surprising link between temperament and whether you are right-handed, left-handed, or ambidextrous. Researchers have found that people who express no preference for using one hand or the other have higher than expected levels of generalized anxiety disorders. A recent study on noise phobia in dogs found similar results—dogs who used either paw to stabilize a stuffed toy (so that they could lick out food) had a higher frequency of noise phobias than dogs who were right- or left-“pawed.”
⁵
Handedness is inherited in humans, and we have every reason to believe it is in dogs too. If being ambidextrous is associated with an increased risk of generalized anxiety disorder, then the disorder itself is most likely passed on genetically as well.

More evidence relating brain function and fearfulness comes from studies of people with autism. Autistic people respond to faces as if to threats, not because they don’t recognize them, but because autistic people’s amygdalas are always overactive. We don’t know exactly what causes autism, but there’s no question that it has a lot to do with the function and chemistry of the brain, matters influenced both by genetics and, as we saw in the last chapter, early development. Individuals with a variety of anxiety disorders also have overactive amygdalas, and this relationship between genetics, the workings of the brain, and the experience of fear is just as pronounced in other animals, including our dogs.

A good example of the interplay between genetics and fear is the type of fear that biologists call shyness, one of the many aspects of life we share with dogs. Anyone who’s ever had to walk into a crowded party, not knowing a soul in the room, can empathize with a dog cowering behind her owner’s leg at doggy day care. Our level of discomfort around unfamiliar people varies—sales reps are known for their lack of it—but most of us have felt shy at some point in our lives. How often and how intensely you feel shy turns out to be influenced by your genetics, just as it is in your dog.

What’s different about this type of fear in people and dogs is the
way it is expressed. We think of shy people as passive, retiring folks who stay in the background, speaking quietly if at all and avoiding the spotlight. However, to dog trainers and biologists, “shyness” refers to a specific type of emotion, the fear of the unfamiliar. What action a dog takes in response to this fear can vary widely, from hiding behind the couch to the canine equivalent of pulling out a shotgun when a car drives up.

Although the fear of meeting new people is common in our species, many dog owners seem surprised, even shocked, when their dog behaves one way to the family, and another way to strangers. “But he’s so sweet!” they say, almost pleadingly, in a consultation, while their dog sits in the corner and avoids me. He may be hiding his head behind the chair, or he may be growling under his breath because he’s trapped in a room with a stranger, but both responses are motivated by fear. I have no trouble believing that their dog is exuberantly friendly to the family, but that doesn’t mean he will be to people he doesn’t know. Shy people behave differently around their close friends than they do with strangers—why should dogs be any different?

Even so, it seems hard for some people to understand that the dog who is sweet and loving to them may not behave that way toward everyone. No one knows this better than delivery workers, whose amygdalas light up when they hear the words, “Oh, don’t worry, he’s just
fine
!” as a household dog tries to lunge through the screen door toward them. “Fine” often means the dog is wonderful with the family, but it doesn’t say much about how he behaves toward anyone else. Dogs sort the world into “familiar” and “unfamiliar,” and you can’t understand dogs if you don’t understand that. Of course, we humans don’t see the world all that differently. If you woke up in the middle of the night and found someone standing in your bedroom, wouldn’t it make a difference if he was a trusted friend instead of a complete stranger?

It’s understandable that people have a hard time equating growls and bites with fear, especially the kind of fear that biologists and animal behaviorists call shyness. We’re used to associating shyness with timidity, so it’s hard to look at what appears to be an aggressive dog and
think of her as shy. After all, shy people usually don’t attack visitors; why would shy dogs?

There are probably many reasons that dogs and people express their discomfort around strangers differently. Surely one of them is that adult humans are often able to avoid social encounters that make them nervous, whereas our dogs are often not given the choice. There they are, tied up in the front yard, or trapped on a leash, unable to avoid contact with people they don’t know. Even if they do have a choice, dogs have no idea who is an acceptable visitor and who isn’t—how are they to know that the stranger at the door is delivering a package rather than threatening the den? With the rational, thinking parts of their brains radically smaller and less efficient than ours, dogs simply can’t think through all the complexities of human social interactions and talk themselves down from feeling afraid. If they have what is called an active defense reflex, then they’re going to go after what scares them, rather than run away from it.

It’s also helpful to note that although most of us think of shy people as being timid, some shy people report that they become overly assertive, to mask their fears. Melvin Belli, the flashy American attorney, said he became flamboyant to “hide his own shyness.” Here’s a passage written by a boisterous woman who describes herself as very shy:

Statements like these make me think of dogs who barrel into my office and leap all over me, the desk, and anything else that gets in their way. These dogs are full of energy, but they are as quick to jump on the furniture as they are to jump on you. You get no sense of connection with these dogs—and if you look past the exuberant activity, they don’t seem to have any interest in relating to you at all. I’ve come to think of them as frenetic rather than friendly, and increasingly I find myself wondering whether some of them are the Melvin Bellis of dogdom.

However it’s expressed, there’s little question that the fear of the unfamiliar
is a common trait in the animal world. One early study on shyness in humans found that 80 percent of respondents described themselves as shy at some point in their life, and 40 percent of them said they were still shy as adults. Four percent said they were shy
all
the time, in
all
new situations. That study showed that shyness was relatively common, but at that time, we didn’t know how it developed, or how much of it was learned and how much inherited.

People long ago came to suspect that this type of fear was heritable in humans, but the early studies were confounded by the influence a shy mother has on her baby. The evidence was overwhelming that shy mothers tended to have shy children, but until researchers looked at adopted babies, we couldn’t separate out nature from nurture. It made sense that shy mothers would behave differently than bold ones, and that in itself might be enough to influence a child’s behavior. In 1985, researchers answered the question by comparing babies raised by their biological mothers to babies raised by adoptive mothers. All the babies had been born to shy mothers, but the adopted infants were raised by mothers who were not shy. Such studies, called cross-fostering studies when performed on animals, help us sort out the influence of genetics from the influence of the mother during early development. Although the mothers’ behaviors did indeed affect the children—shy mothers raised the shyest babies—there was also a strong genetic effect. Infants born to shy mothers were still somewhat shy, even when raised by moms who weren’t. Advocates of the “nurture” side of the equation argued against the influence of “nature” (genetics) for decades, but countless studies have made clear that nature has a profound effect on whether an individual will tend to be shy or bold.

The same result has been found in many animals, including our primate relatives. Stephen Suomi, a primatologist at the National Institutes of Health, has spent decades studying shyness and has found that about 15 percent to 20 percent of several monkey species are “excessively fearful” of novel individuals or situations. Shyness has even been found to be heritable in one of the world’s hardest-working animals, the laboratory rat. Perhaps you’ve heard about the work reported a few decades ago on “maze bright” and “maze dull” rats, in which researchers selectively bred rats depending on how quickly they could run a maze. In just a few generations, they’d bred a group of rats who were able to move through a complicated maze in no time, especially
compared with the “dull” group, who were bred for their lackluster performance. Only there was one problem—it turned out that “bright” and “dull” rats (read “smart” and “stupid,” although the researchers were too gracious to use those terms) weren’t at all different in their ability to solve problems. The “dull” rats were simply afraid of new environments, and when placed in one were less likely to explore than the “bright” ones were. The “bright” ones may have won blue ribbons in the laboratory, but they’d be the first ones eaten by a hawk in the wild— a good reminder of why shyness tends to hang around in the gene pool.

Fear of the unfamiliar may not be blatantly obvious in laboratory rats, but it can be easy to spot in the dogs that live in our homes. We’ve all known dogs who were “a bit cautious” around visitors, or who were afraid of new places. This tendency to be cautious around unfamiliar things is as strongly influenced by genetics in dogs as it is in people. Studies done as early as 1944 supported the idea that the fear of strangers can be inherited in dogs. The researchers found that out of 178 dogs bred in one laboratory, 46 percent were extremely shy. This surprisingly large percentage turned out to be due to the disproportionate influence of one extremely shy Basset Hound bitch, who produced 59 of the puppies in the study, 43 of whom were “shy and unfriendly.” Another study in 1958 reported significant breed differences in fearful responses to novel objects (for example, a mechanical snake or an inflated balloon), finding that individuals of breeds such as Collies, German Shepherds, and Corgis were most likely to be wary of unfamiliar things, while Boxers, Scotties, and Boston Terriers were the boldest. The famous twenty-year study done by Scott and Fuller on the genetics of dog behavior confirmed that shyness, although strongly influenced by experience during early development, was also affected by genetics.

More recently, some researchers have found that fearfulness was the one personality trait that could be predicted by puppy “temperament” tests, if the tests were given at twelve weeks (instead of the more common seven or eight weeks). The research also found that the tests were most predictive if given at six months of age, a good reminder that heritable traits don’t necessarily appear in the first few months of life. After
all, well-bred sheepherding dogs, whose stalking behavior around sheep is as hardwired as walking, often don’t “turn on” to stock until adolescence, even late adolescence. I have always found it amazing that an inherited trait like the “Border Collie eye” was so variable in the timing of its first appearance. You can see it in some eight-week-old puppies, but others pay no attention to sheep until, one day, even as late as fourteen months of age, they happen to glance at the sheep and, in an instant, their heads drop and their eyes focus like a heat-seeking missile system. “Eye” doesn’t develop step-by-step; rather, it’s as though someone turned a light switch from “off” to “on.” All this is to remind us that just because a behavior is influenced by genetics doesn’t mean you’re going to see it in an eight-week-old pup, although a tendency to be fearful appears to be relatively stable through time.