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.
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."