Listen to the herd

“Collective fear stimulates herd instinct”, said Bertrand Russell, and as a matter of fact, even when our teachers or our parents try to teach us differently, there are some situations  that make us all act like one sheep in the herd. However, being so similar can bring us some benefits. But how?

Iker Zuriguel, Ángel Garcimartín and other colleagues from the PhysicsDepartment of the University of Navarra have studied the flow of sheep through a bottleneck. “There are times when mobs have to pass through a bottleneck, such as in the case of an emergency exit. If there's panic in the crowd, a jam can obstruct the way out”, explained Prof. Zuriguel. The majority of research in this area has focused on inert particles when they clog the exit of a silo or a pipe. But what if their results can be applied to living creatures that behave like humans, pushing and moving in a panic situation? 

This team of the University of Navarra has made several experiments with sheep and the research has shown important and unique results. For example, in a bottleneck, the relevant quantity is not only the average flow or the evacuation time; it is crucial to take into account other information that describes how time lags between individuals are distributed. “If we only measure the time that a given number of sheep take to pass through a door, we could miss relevant information, for example, that during 6 seconds two of them were stuck in the door. For humans, that apparent small amount time can be extremely dangerous”, said Iker.

In the farm, advised by the shepherd and a group of veterinarians of the University of Zaragoza, they also found that placing an obstacle before the exit improves the evacuation process as sheep avoid jam and manage to cross the door in a shorter amount of time, more swiftly and without accidents.  It seems, moreover, that the best place to position that obstacle would be at a distance approximately equal to the door size.

As experience shows and even if it´s hard to admit, we all act like sheep when the moment arrives, so let´s keep an eye on the herd and learn from what they have to say!

Patricia Sáinz de Robredo

Communications