Grasshopper Aggression

When does an inoffensive little green grasshopper transform into a ravenous beast that destroys crops? When it becomes a locust. Mention the word locust to many people and it conjures up an image of a horde of voracious insects that invade and eat everything green in sight. Like army ants or a swarm of mosquitoes, locusts congregate in vast clouds of plunderers which will quickly consume precious plants and then move on, leaving behind a barren landscape.

It's interesting that only recently have scientists figured out where locusts come from. They seem to pop out of nowhere, do their damage, and move on. What triggers their amassing and subsequent invasion? Recent studies have shown that locusts are the Hyde side of the gentle Dr. Jekyll—from Robert Louis Stevenson's tale The Strange Case of Dr. Jekyll and Mr. Hyde, in which Hyde becomes the evil alter-personality of the good doctor.

When hard times come—such as drought or famine—hungry grasshoppers begin to cluster and rub up against one another. This pushing, shoving, and agitation releases serotonin into their bloodstream and brains. Suddenly they begin to grow larger, they turn from green to black and yellow, they crowd even closer and become aggressive. Soon they're on the rampage, as the swarm moves off, looking for food. It's as if their stressful behavior spreads through the mob, turning them into a threatening horde. Their interactions can become so belligerent that they will later turn to cannibalism, as plants become increasingly scarce. Like a bad dream, locusts abruptly appear, do their frightening thing, and then disappear.

Entomologists have known the basic qualities of locusts, but have not given them the attention they deserve. Why might that be? One theory suggests that humans see themselves as similar to gentle grasshoppers—in that, under stress, we too change our personality. We'd prefer to view ourselves as having a fixed personality—in which we present an enduring face to others. We also like to believe that we're in charge of who we are and can control our behavior. Instead, our environment plays a significant role in how we behave; other people directly influence us and cause us to act in different ways. Sometimes we literally get out of control. We can do significant damage. Tension can turn us into abusive beings.

So are we humans sometimes like the gentle grasshopper, munching imperturbably on our thoughts, in command of our behavior, staying cool when disturbed? Or are we reactive critters who, under stress, turn nasty and beat up on others? Are we grasshoppers or locusts? Or both?