Get out of the way!

TURNING right onto a Santa Monica freeway onramp, Ran Klarin heard the official theme song of the offended L.A. motorist -- the blaring horn like an air raid siren, as if Armageddon were under way. But this driver, who was turning left onto the onramp, didn’t stop there. Furious that Klarin had moved before him, he raced in front of him, stopped and blocked him in. Then he jumped out of the car and stormed over for a confrontation.

“He hit me in the shoulder and said, ‘What ... you doin’?” says Klarin. A high school administrator from Santa Monica who tangles daily with juvenile bravado, Klarin responded with outrage of his own. “I was feeling challenged. I wanted to get out of my car and get into it with this guy.”

Most gridlocked Angelenos know the fury triggered by an invasion of blacktop space, which can send a mild-mannered commuter from zero to primal scream in an instant. The catalyst of this transformation, though, may be a mechanism that goes back to well before the dawn of asphalt: territorial behavior.

Some scientists now think road rage and other personal space disputes -- neighbor feuds over intrusive flora or spats with gym hogs who won’t let others work in -- boil up from responses selected by evolution to protect resources and ensure survival of the species. Recent findings in the field of evolutionary psychology suggest that a mandate to defend turf is at the root of some of the species’ most irrational and violent behavior: jealousy, assaults, murder.

“Humans have developed adaptations to prevent people from encroaching on our stuff,” says David M. Buss, whose latest book, “The Murderer Next Door,” examines how these changes, such as territorial mate-guarding and jealousy, play a role in homicides. The impulses are part of a survival program designed to make us react first and think later, if at all.

“When someone cuts us off on the road, it triggers an ancient evolved adaptation to protect social reputation,” Buss says. “People become known as the kind who won’t take any ... or the kind you can exploit with impunity. If the person fails to respond to the trespass, then it signals exploitability. It tells the trespasser that he/she can trespass in the future.”

More than a bruised ego is at stake. People who are “exploitable” might be less likely to attract a mate and propagate -- the mandate behind most territorial behavior, Buss says.

The problem is that territorial behaviors weren’t designed for the 21st century. Instead of leading to increased power, resources, food or mate prospects, they often result in conflict, court bills, injury and death.

That’s because territorial overreaction, say experts, has outlived its usefulness in the post-hunter-gatherer world.

“We don’t live in small groups anymore. We regularly deal with strangers. The world is a very different place. We haven’t caught up genetically to that,” says Frank McAndrews, a psychology professor at Knox College in Galesburg, Ill., who has studied territorial behavior in public spaces.

As evolutionary psychologists shed light on more of what’s behind the impulse to evict space interlopers, their findings can help us step back from the brink.

Klarin came to his senses as the irate driver slammed his hand violently on the car. He countered his reflexes with the realization of what was missing in this emotion-charged moment: rational thought. This was crazy. He rolled up his window, which defused the situation, and the guy steamed back to his car.

Space issues

Psychologists are reluctant to call our territorial imperative an instinct, which would lump us in with any old animal, for crying out loud. But there’s little doubt that humans have a reflexive need to protect space and resources that extends well beyond security codes and livid Rottweilers.

These space demands aren’t uniform -- the reactions to violations vary by degree of ownership, cultural norms, proximity and personality. We have the most intense reactions over attacks on “primary territory,” the stuff that’s legally ours (home, car, family).

Police blotters and court logs brim with unneighborly boundary feuds waged over incursions of trees, hedges or itinerant lawn mowing. A Florida resident who had some trees chopped down by a machete-wielding neighbor told the St. Petersburg Times, “I should have shot him while I could.”

People take these intrusions as personal attacks, because, well, they are. They’re assaults on social status, behavioral scientists say.

“The fact that someone would be treading on your territory and seeming not to worry about it very much indicates a lack of respect for you,” says McAndrews. “We react to that strongly, because, at least for males, status was the whole key to success. If you didn’t have status, you didn’t have powerful allies. You didn’t attract desirable mates.”

This is also why road encounters are so potent. Cars put you in primary territory in public space, so there’s a sense of entitlement and dominance that comes with that -- and more outrage at invasions of our home on wheels.

We tend to have more conflicts in “secondary territory,” a realm where ownership rights are more fuzzy. These can be caused by stereos or party noise booming into our airspace, cars parked along the curb in front of our house, or maneuvering on freeway onramps.

“Public territory,” such as fast-food seats or park benches, isn’t as inciting -- unless we’ve marked our territory. When somebody shoves aside the coat or magazine staking a claim, people get “very upset,” McAndrews says.

Then there’s the personal space zone, often invaded by close talkers and backslappers. Humans follow the animal line here. Elephants, for instance, have an invisible no-go zone that fans out around them. Cross it and you’ll get a loud trunkful or be charged.

Americans need at least an arm’s-length’s bubble around them, according to anthropologist Edward T. Hall, the father of “proxemics,” which studies the use of space within culture. Hall says the “personal distance” zone of a typical American is 18 inches to 4 feet.

Yet in some cultures, a foot and a half is equivalent to having your own presidential cordon. Complete strangers in Brazil will put an arm around you after an introduction, male-to-male included, while making your way through a jammed street in Calcutta is an audition for roller derby.

Whether we explode on an encroacher depends on the length of our fuse and if it’s already lit.

“It’s usually anxiety that is the driver,” says Dr. Charles Sophy, a psychiatrist in Beverly Hills and medical director of the Los Angeles County Department of Children and Family Services. “You might be in a bad mood. You may have just had a fight with your boss, stuff that can push you over the edge.”

As personality traits vary from person to person, so does the intensity of the defense, which can quickly flash out of control. Unlike bees or bears, which ward off intruders of the same species with a charge or a claw, territorial rage can make humans kill, on display in the Congo, the Middle East and on the turf of Bloods and Crips.

“Being dissed publicly, even if the insult is seemingly trivial can lead to violence and even homicide,” says Buss. “Selection has designed ... that powerful motivation to maintain, cultivate and preserve reputation,” which was critical in caveman days to reproductive success.

Although everyone wants to protect hearth and home and prevent increasing invasions of privacy, extreme territorial behavior can sabotage, not ensure, security. Overreaction “can interfere significantly with our life,” Sophy says. “It raises the level of confrontation with others and alienation from others. It can lead to physical altercations.”

Partner protection

Jealousy and mating issues may evoke the most basic, and the most deadly, territorial responses.

The most studied aspect of territorial behavior, mate guarding developed to fend off mate poachers and prevent mates from taking their reproductive resources elsewhere. In a November paper on the evolution of jealousy in Trends in Cognitive Sciences and in studies published last year on mate-retention in marriage and violent mate-guarding strategies, Buss and coauthors lay out the case that evolution designed traits for humans to defend sexual turf.

Buss has identified 19 different mate-guarding tactics that have evolved to guard sexual resources. Although some are relatively innocuous, such as a man putting an arm around a wife or girlfriend when a handsome or wealthy character approaches (and vice versa at the threat from an attractive woman), the vigilance can escalate to threats and violence.

In one example of how jealous rage can explode out of control, Buss cites the story of a man who touched the rear end of a woman in a bar. She called her boyfriend, who raced over to confront the offender and ask for an apology. When all he got was a laugh, the boyfriend followed the man home and beat him to death with a baseball bat.

Jealousy is the driving force behind mate-retention, hatched by natural selection to send us to battle stations at perceived threats to our reproductive success.

With male sexual jealousy the cause of more than half of spousal murders, according to Buss, researchers have been trying to find the patterns in mate-guarding that lead to violence. One study found that verbal disparaging, sequestering a mate from friends and family and monopolization of the mate’s time can be violence predictors.

Each gender deploys different guarding techniques -- a man might yell at a woman for talking to another man, a woman might threaten her partner with a breakup -- and different emotional triggers. Men are most likely to fly off the handle at a mate’s physical infidelity; women get most upset by emotional infidelity, Buss said.

Though the tactics are different, the behavior links us firmly with the lesser critters of the planet. The battle for territory in the animal world, concentrated in a particular space, also puts mate defense front and center.

In southeastern Arizona, the male megachilid bee guards its 6-foot clump of mint plants from all male interlopers, as it’s programmed to do by instinct. John Alcock, a biology professor at Arizona State University, has studied the bees in action, and it’s not hard for him to draw a connection with humans.

“The males patrol their area relentlessly and strike any other male insect and males of their own species violently in flight and drive them away,” he says, while females are allowed to buzz in for pollen and trysts.

Human mate-guarding “has a fundamentally similar basis to that exhibited by a host of other animals.”

Except the defensive catalyst in humans is emotion.

“Emotions evolved to trigger the right kind of behaviors in us,” McAndrews says. “We get jealous when it looks like somebody is stealing our partner, because jealousy is going to motivate us to do something to eradicate the threat.”

Clearing the mind

But we don’t have to be run by default caveman/woman tantrums. Researchers and psychologists say we have another option: recognizing the territorial flash points and catching ourselves in the act. Cooler heads can prevail in a world that favors mind over madder.

The reflex to hoard and defend is obsolete in the organization age, says Annette Simmons, president of Group Process Consulting, author of “Territorial Games” and an expert on office turf wars. “It’s not the best protector who gets the most goodies, it’s the best connector.”

Fear is a defensive emotion that can take two very different pathways to the brain, a slower route through cortical processes and reason, or a direct sprint to the most primitive part of our gray matter, the amygdala, for instant panic.

“That makes you stupid,” adds Simmons. “It narrows your input and puts you in fight-flight mode. Hold your peripheral vision and continue to see the big picture, and keep breathing.”

Sophy says we need to identify our territorial triggers and, when one hits, to ask ourselves: Is this a real intrusion or is this just me being reactive? That allows us to channel territorial fear through the slower pathway to an interpretive, reasoned response.

Your behavioral selection, it turns out, trumps evolution -- and manipulation by a brain that thinks the year is 50,000 BC.