The mystery of the giant grasshoppers

Fields that roam grasshoppers, the herd of dolphins all over the world have swung without ever colliding . Why do they do that? A British scientist wondered why.

So far, Iain Couzin, 34, a blushing face with glass-clad glasses, still shuddered as he rethinked his field trip to Mauritania.

"We want to know how Africa's locust epidemic arises," said British biologist, working at Princeton University.

"Desert grasshoppers are shy solitary animals, staying away from each other if possible," Couzin explained. "But when they reach a critical density they suddenly come together in a line and form giant grasshoppers that can devastate large areas." Why?

Couzin discovered a strange thing through experimentation: Shortly after the experimental animals began to line up, they bit each other in the back of the tail. He severed the nerves between his chest and abdomen so that they could no longer feel anything from the tail. "After that they didn't go into rows anymore. The whole group broke up."

The researcher suddenly had a bold thought: Is it true that cannibalism motivates insects to become in line?

To answer this question, he made a trip to North Africa: "It was a failure."

Researchers are increasingly going into the Sahara desert - but only grasshoppers are not found. By the time they were about to run out of food and drinking water. "Fortunately, a Bedouin passed by and sold us live camel meat," Couzin grimaced.

After the last few weeks the researchers also found some lost grasshoppers in the desert sand. But how long they were happy. "While touching them, soon my hands turned into two shapes full of blisters," he lamented and showed a photograph of him looking into the desert with his hands covered with ice. . The grasshoppers' skin is a highly active chemical.

The fish swim in the shape of a cake.(Photo: National Geographic)

But it is not required to be this poisonous desert grasshopper. They have found solutions from observations on other species, those with collective behavior such as ants, herring, starlings or even humans. For Couzin it is a puzzle of collective intelligence: How did each individual's actions combine to become a complex move of a group?

For example, how can a flock of fish change direction quickly like a lightning when a shark appears? How do migratory birds agree to form the best flying squad? Who decides how many ants have to leave the nest to find food?

"There is no need for a leader for those decisions," Couzin said. An individual does not need to be intelligent, they do not need to understand or look at the whole thing what the group is doing - but when in the flock they are more intelligent.

The most impressive for Couzin is the lesson from the hundreds of thousands of ant colonies that he observed in the original Panama forest a few years ago.

"They are in fact blind but move quickly and unbelievably, they are very accurate, and build bridges with their bodies to overcome the underground holes." At the entrance of the nest, he discovered a 3-lane "highway" form : In the middle were ants who were prey to the nest and flanked by ants. This very orderly moving crowd stretches up to 140 meters through the forest.

How do the ants find their way, why not collide with each other and especially: Why are they never blocked as in human traffic? "We humans also need such an efficient transportation system," said Couzin and smiled. "Ants have the advantage of evolution. That's why we're trying to learn from them."

He developed a computer-based biology model of ants: In which the exchange of information relies only on exposure and fragrance. Because that is the channel that ants understand each other: Ants in the nest have a different smell than those from outside. The aroma of ants looking for prey is the same motivating engine to leave the group. The more food they find, the faster they leave and leave more and more scents, signaling to other children that they need help.

Virtual ants also leave similar traces. In addition, each virtual ant model can move its antenna. If they touch the homosexual, either go forward or slow down and move to the side.

"The model shows that ants have a very narrow operating space," Couzin said. Avoid going too far they will lose the scent of scent. The reaction is too slow, they will hinder the kids from going after it - the start of the congestion. And so is the idea for transportation to form: Antipodal people jostle without tolerance to the nest. The ants leave the nest to the side whenever they touch the same type. And so in the computer model also formed a three-lane highway of ants as seen in Panama forest.

"The traffic principle of ants is simple but can help solve complex problems , " Couzin said. Telecommunications companies want to speed up the conversation connection in the network by using "electronic incense" to signal the fastest connection. Social strategies of ants can also be applied to truck teams or programmers for rescue robots .

Together with engineer Naomi Leonard, who also worked at Princeton University, Couzin conducted an experiment to put fake fish in a herd of fish - with the aim of drawing fish and learning them.

"The more species I observe, the more common patterns I see." For example, people often behave like fish.

To prove it, Mr. Couzin gave many blue spots to move back and forth on the computer screen. " That's a fish flock ," he explained. In order for these fishes to function, the virtual fish only need to follow 3 simple rules: Stay in the flock, avoid colliding and swim in the same direction as the neighbors. Only that much is enough for the swarms to suddenly move: Suddenly blue points of the mobile line tail each other into a spinning circle, like a spinning wheel. "When I saw this model for the first time, I thought there must be an error in the program," the biologist admitted. "But really, fish sometimes swim like that."

And so is man. Couzin discovered this with many University of Leeds researchers through an experiment. They instructed many groups, each consisting of 8 participants, to walk in the same direction, stay close to each other, not stand back, do not speak to each other and did not signal. The time until the pattern formed was like that of a spinning wheel that never lasted too long. "That is the best strategy to save energy while always having to move."

In the second step, the researchers tested how the group would react when individual members drove them in a certain direction. "Movement corresponds largely to the model of the fish," Couzin said, "if excluding complex interactions such as speaking or negotiating with one another, a group of people still acted according to the same rules. just like another pack. "

And the researcher also believes that the riddle of grasshoppers has now been solved - just as far away as Mauritania. He discovered that the mormon crickets (Anaburs simplex) in America form the herd according to the same rules as the desert grasshoppers.

To study, we just need to go to Idaho. "There, only after 5 days we had enough data," said Couzin triumphantly. His findings: The mormon crickets line up during hunger - they lack protein and salt. The less these substances, the more aggressive they are. "They always seek to eat children in the front and in the meantime try to avoid attacks from behind." Not only hunger but also the danger of being eaten from behind started the flock of insects. "This discovery really stunned us."

Now Couzin is looking forward to a fascinating study: Cancer Cells. "They exchange information through transmitters and go through tissue together," he announced. Now he wants to know if these malignant cells are similar in behavior to ants, grasshoppers or humans.