This brings me to the fundamental question you have to ask yourself any time you’re trying to solve a problem with aggression: is the aggression coming from fear or dominance? That’s important, because punishment will make a fearful animal worse, whereas punishment may be necessary to curb assertive aggression.
Pain-Based Aggression
This one is simple and is something all humans have experienced themselves. Pain makes you mad. A person in pain will become irritable and start snapping at the people around him, but an animal can easily become aggressive. Vets have to watch out for pain-based aggression with any animal who is suffering. A dog who has been hit by a car may lash out and bite its owner due to pain. An animal who has arthritis or some other painful condition may become aggressive when the painful limb or joint is manipulated.
Intermale Aggression
Intermale aggression is linked to testosterone levels, which is why castrating a male dog can stop his fighting other male dogs. However, castration doesn’t fix dominance aggression in a dog, which leads Dr. Panksepp to believe that intermale aggression may actually be a third form of primary aggression separate and distinct from either predatory aggression or affective aggression. Time will tell.
Irritable or Stress-Induced Aggression
Animals who live in highly stressful conditions are more prone to aggression than animals living in reasonably calm conditions. I heard about an awful case of stress-induced aggression where a Border collie ate all her puppies. Borders are a nervous, high-strung breed, and this particular collie ate her puppies after she had been taken on a long car trip and brought to a new house. Her stress levels were already very high because she lived in a dysfunctional household that included a hyperactive teenager who could never sit still, and apparently the long journey and brand-new surroundings tipped her into violent aggression against her own pups.
Even a constant relatively minor irritant like a flea infestation can trigger stress-induced aggression in an animal.
Mixed Aggression
In real life animals probably experience more than one motivator for aggression pretty often. In particular, we know that fear-based aggression and assertive aggression often co-occur in dogs. Dr. Panksepp thinks this probably happens with maternal aggression in some cases, where the mother attacks out of fear and out of territorial aggression. He also thinks that if intermale aggression does prove to be a distinct form of aggression, separate from the rage circuits in the brain, it probably doesn’t occur in its “pure” form very often. Two males may go into a fight eagerly, like two boxers ready for the championship match, but rage probably kicks in as one or both males start to feel frightened, frustrated, or in pain. Then you have intermale aggression mingled with potentially three different kinds of affective aggression.
Pathological Aggression
Medical conditions like epilepsy or head injury can produce pathological aggression in an animal. This is true in people, too. For instance, we know that a lot of prisoners who have committed violent crimes have had head injuries at some point in their lives.
GENETIC TENDENCIES TO AGGRESSION
Some animals are genetically disposed to higher levels of aggression than others no matter what the circumstances. There are bloodlines of rare horses that have killed or injured grooms, and cattle breeders have observed that certain genetic lines of bulls are more aggressive than others. I’ve already mentioned the behavioral problems that crop up with single-trait breeding. The rapist roosters are the most dramatic case, but many pigs have become more innately aggressive, too. A study at Purdue University showed that pigs bred to be lean got into more fights than pigs from a fatter genetic line.
The genetics of aggression is an especially thorny issue with dogs. Most people don’t want to believe that there are some breeds, like pit bulls and Rottweilers, that are more aggressive by nature. (Pit bulls aren’t an established AKC breed.) Usually these folks have known or owned individual Rotties or pits who were sweet and good-natured, so they conclude that when a Rottweiler or a pit bull shows aggression the problem is the owner not the dog. But the statistics don’t support this interpretation, although it’s true that statistics on dog bites aren’t hard and fast.
There are lots of problems with dog bite reports. For one thing, there are a few different kinds of dogs that are called pit bulls, including some purebreds like the American Staffordshire terrier and some mixed-breed dogs. Another problem: large dogs do more damage when they bite people, so they’re probably overrepresented in the statistics. Also, lots of purebred owners fail to register their dogs with the AKC, so it’s impossible to know exactly how many purebred Rottweilers there are in the country and compare that figure to the number of reported dog bites committed by Rottweilers.
Because dog population data is imprecise, no one can nail down exactly what each breed’s “aggression quotient” is compared to other breeds. Still, you can get an overall picture of which breeds are most dangerous by looking at medical reports of dog bites. On average Rottweilers and pit bulls are so much more aggressive than other breeds that it’s extremely unlikely bad owners alone could account for the higher rate of biting. And if you’re looking only at anecdotal evidence, there are plenty of cases of nice, competent owners with vicious Rottweilers or pit bulls. Aggression isn’t always the owner’s fault. Writing about pit bulls, Nick Dodman says, “Originally bred for aggression and tenacity, pit bulls, if provoked, will bite hard and hang on, making them as potentially dangerous as a handgun without a safety lock…. they can become quite civilized, developing into loyal and entertaining companions. But the potential for trouble is always lurking somewhere, as a result of their genes and breeding.”11
The Monks of New Skete, the famous trainers of German shepherds in upstate New York who wrote The Art of Raising a Puppy, say that every breed of dog has its freak bloodlines that produce dogs who are much more likely to be aggressive.12 Some people have always bred dogs with enhanced aggressive behavior to serve as guard or police dogs; there are also drug dealers and other unsavory types who have deliberately bred very aggressive dogs either for protection or because they’re part of the illegal dog fight scene. These dogs are like a gun with a hair trigger and no safety.
As I mentioned earlier, Rottweilers and pit bulls are the worst offenders now.13 But before Rottweilers and pit bulls got so popular the most dangerous breed was the German shepherd, and Chow Chows show up in dog bite studies as having a much higher rate of biting per dog than other breeds.
The same study also found that male dogs are 6.2 times more likely to bite people than are female dogs, and intact males are 2.6 times more likely to bite people than neutered males.
Finally, there are some animals, including some dogs, who are just plain trouble. It’s not their breed and it’s not their owners. It’s them. They’re born that way, and they are bad, dangerous dogs.
If you’re trying to buy or adopt a dog with the absolute least genetic proclivity to aggression, your best bet is probably a female, mixed-breed adult. However, it’s really not necessary to be hyper-vigilant about the genetics of dog bites when you’re choosing a pet. Serious dog bites are so rare that from 1979 to 1994 only .3 percent of the U.S. population got bitten badly enough to seek medical care. When you consider the fact that just about everyone in America who isn’t living in a prison or a nursing home has fairly regular exposure to dogs, that’s a very small number. You’re better off thinking about how a particular breed of dog, or a mixed-breed dog, will fit into your life.
ANIMAL VIOLENCE
People who love animals often think of animals as being aggressive but not violent. Only humans, they’ll tell you, commit rapes, murders, or wage wars.
But that turns out not to be true. Some chimpanzees actually fight what Jaak Panksepp calls mini-wars. This is organized, violent behavior. Two groups of males from rival troops will meet at the border between their territories and fight. So many chimpanzees die in these mini-wars that in a lot of
places the ratio of adult females to males is two to one. Jane Goodall has talked about how upset she was to find out that her beloved chimps could do something so awful. War is not unique to human animals.
I’ve heard many stories of violent behavior in farm animals. A woman I met told me about an expensive ram she bought from a small hobby farm (that’s a farm whose owner raises farm animals as a pastime, not a full-time business). The ram was perfectly tame and gentle around people, so she thought he was fine, and she put him out with her twenty ewes. The ewes had already been bred and were in the early stages of pregnancy so they didn’t come into estrus. The ram smashed their sides in and killed them all.
Many animals can be horrifically violent for no reason, it seems, other than the sheer desire to kill and maybe even to torture. It took many, many years for people to finally realize that dolphins, for instance, aren’t the benign, perpetually smiling sea creatures they look like to us. Instead, dolphins are big-brained animals who commit gang rape, brutal killings of dolphin “children,” and the mass murder of porpoises. In her book To Touch a Wild Dolphin, Rachel Smolker writes that male dolphins stick together in gangs and will chase a female down and forcibly mate her. Female dolphins don’t form groups the way male dolphins do.14 Reading the book I found the similarity between dolphin gangs and human gangs creepy.
There was evidence that dolphins were killing babies and porpoises for years, but researchers just didn’t see it. They kept thinking that the porpoises must have been killed by boats or fishing nets. Finally someone pulled a porpoise who had just been killed out of the sea and found tooth marks on its side that perfectly matched the teeth of a dolphin. Ben Wilson, a dolphin expert at the University of Aberdeen in Scotland, told the New York Times that when he realized it was the dolphins who were doing the killing, his reaction was, “Oh my God, the animals I’ve been studying for the last ten years are killing these porpoises.”15
Animal experts always manage to make infanticide seem not so bad. The standard explanation is that adult males have evolved to kill babies in order to bring the mother into estrus so she can have their babies. That could be true, but when you put infanticide together with other animal violence you may start to wonder just how evolutionary it is for an adult male to kill a baby of his own species or even his own group. Is animal infanticide really what nature intended? Or is it, at least some of the time, an aberration of what nature intended?
A videotape about the predatory behavior of killer whales made me see animal aggression differently. The different pods had each developed a different killing specialty. Some pods killed tunas they stole from fishing lines; some killed seals; some didn’t do a lot of active killing. They just swallowed the fish whole. One pod had even figured out how to kill penguins, bite a hole in one end of the bird, and then squeeze on the other end until the insides came out of the feather “wrapper” so they could eat them. It was like squeezing toothpaste out of a toothpaste tube.
But one pod had become killers for sport. The cameraman filmed the pod separating a baby whale calf of another whale species from its mothers and killing it. They crashed their bodies on top of it over and over again, pushing it underwater repeatedly until finally it drowned. It took them six or seven hours to kill the baby. Then they ate the tongue and nothing else. It was horrible.
The report didn’t say whether the adults were males, but I expect they were. We do know that most of the violence seen in killer whales is done by adolescent males, just as it is in humans. Sociologists have found that boys and young men between the ages of fifteen and twenty-four are most likely to be engaged in violence compared to other age groups. That makes me think that the kind of killing those whales were doing isn’t evolutionary. Maybe it’s a negative side effect of immature brain development.
With dolphins, researchers have pretty much reached the conclusion that much of the killing they do serves no evolutionary purpose. Dolphins will slaughter hundreds of porpoises at a time. The only imaginable evolutionary reason for this would be if porpoises compete with dolphins for the same scarce resources, like food. But they don’t. Porpoises eat different food than dolphins do. Killing a porpoise doesn’t increase a dolphin’s chances of surviving and reproducing in any way. The only conclusion is that dolphins kill porpoises because they want to.
I don’t know why animal violence happens, but when I read through the research literature I’m struck by the fact that the animals with the most complex brains are also the ones who engage in some of the nastiest behavior. I suspect people and animals probably pay a price for having a complex brain. For one thing, in a complex brain there may be more opportunities for wiring mistakes that will lead to vicious behavior. Another possibility is that since a more complex brain provides greater flexibility of behavior, animals with complex brains become free to develop new behaviors that will be good, bad, or in between. Human beings are capable of great love and sacrifice, but they are also capable of profound cruelty. Maybe animals are, too.
WHY DOGS DON’T BITE PEOPLE
All animals have ways of managing their aggression. This is one place where evolution has to come in: it might be good for an individual animal to murder his rival, but it wouldn’t be good for the species if it was normal for animals to fight each other to the death. Few adult animals apart from humans ever attack each other so violently that one of them dies.
Dogs have an inborn guard against excessive killing called bite inhibition. A typical dog learns bite inhibition through puppy play. Dr. Michael Fox of the Humane Society of the United States has found that prey killing and head-shaking movements first occur in four-to-five-week-old puppies during play, and if you watch two puppies playing it’s incredibly violent. They’ll snap and snarl and lunge at each other’s throats—I’ve seen one puppy grab another puppy’s throat, bite down, and shake his head violently, just like he’d do in a killing bite. But the minute the other puppy gives the tiniest squeak the biting puppy lets go. That’s how they train each other that it’s okay to bite “this hard but no harder.” There are probably mechanisms to inhibit biting in all predators, because animals who are armed with teeth need to be able to stop biting before they rip each other apart.
Dogs have another method of teaching each other what’s an acceptable level of aggression. When one puppy is getting too rough, the other puppy will suddenly stop dead in its tracks and stand stock-still facing the rough one. That always stops the other puppy, too. It’s like a time-out. You’ll see it a lot if you watch a younger, much smaller puppy roughhousing with an older, bigger puppy. They’re both puppies, and they’re both young, but one puppy is getting the worst of it thanks to size and age. It’s amazing how fast the two puppies will adjust to each other’s relative size and age. The smaller puppy will get lots rougher, and the larger puppy will get gentler.
Owners who play rough with their dogs are relying on their dog’s bite inhibition to keep from getting mauled. Trainers say that’s not a smart thing to do, because happy play can escalate to angry play if they get too aroused. That’s one of the problems with having a multiple-dog household; the fun can turn violent and two playing dogs can suddenly bite each other for real. Still, even though all trainers tell owners not to play rough with their dogs, owners almost never listen, and I haven’t read about people getting mauled by their pets in the middle of roughhouse play.
Roughhouse play is normal between dog friends, and it’s probably normal between people and their dogs, too. I have seen people play too roughly with their dogs, though. I saw an owner one time play so roughly with his dog that it stopped being play to the dog, and it made her yelp. He was grabbing her loose skin too hard, and she finally growled at him. That’s wrong.
I want to lay to rest one standard piece of dog trainer advice. Playing tug-of-war is probably not as bad as people think. Most trainers will tell you that playing tug-of-war with your dog encourages him to think he’s your equal, which is bad. Other trainers take a slightly different view, whi
ch is that if you let your dog win a game of tug-of-war he’ll be less obedient, but if you win he’ll be more submissive.
However, a study of fourteen golden retrievers in Great Britain a couple of years ago found that neither of these things was true; at least neither was true with the fourteen golden retrievers the experimenters tested. The researchers had people either win or lose a series of tug-of-war games with the retrievers, and then watched how the dogs behaved. The losers were more obedient after playing the game—but so were the winners. All the dogs were more obedient after playing tug-of-war with humans! And none of the dogs suddenly got more dominant. The winner dogs didn’t display any dominance behaviors like raising their tails up high or trying to stand over the person they’d beaten.16 One study doesn’t prove anything, but I think it’s probably both safe and fun to play tug-of-war with your dog, and it might even be good for him. Just remember one thing: the study also found that the dogs who lost every time were a lot less interested in playing any more tug-of-war. Apparently a dog doesn’t like losing all the time any more than a person does.
THE BOAR POLICE
Pigs have a mechanism for managing their own aggression that I call the boar police. Pigs can be really vicious. Any child raised on a farm gets warned repeatedly to stay away from the mama pigs especially. That’s good advice, because pigs don’t have a bite inhibition mechanism that I can see, possibly because pigs are more chewers than biters. When I visit a pen of pigs they’ll start nibbling on my boots; then gradually they’ll work up to chewing harder and harder until I say “Ouch!” They don’t take a social cue like that, either. If the chewing starts to hurt I have to really get on them to make them stop.
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