A researcher from Princeton University spoke about the behavior of organisms as individual units and as groups Monday in SAS Auditorium.

Iain Couzin, a professor of ecology and evolutionary biology at Princeton University, spoke at the third annual Kwangil Koh lecture. Koh was a professor of mathematics at N.C. State from 1968 until 2009.

In the lecture, Couzin discussed behavioral characteristics of animals that primarily move in groups including birds, ants, other insects and fish. In recent years, Couzin said his research has led him through the subconscious aspect of social behavior in animals. 

Couzin said he studied locusts while traveling in West Africa and analyzed their migratory patterns in lab settings. Couzin said he did this from both the perspective of the single organism and from the perspective of the entire group of traveling organisms, which he called the “collective mind.”

Couzin said his research concluded locusts have 12 centimeter radii where they react with one another on a small scale. Another conclusion drawn from his studies was insects, such as Mormon crickets, have cannibalistic tendencies while in swarm formation.

Couzin said this was determined by accident when there were numerous counting errors between the number of locusts going into an experiment chamber and the number coming out after each eight-hour period in the swarming chambers simulated by Couzin and one of his graduate students. 

Researchers determined after this “error” occurred several times that the locusts were eating each other. This launched a new set of experiments that revealed several other conclusions.

By conducting separate experiments in which the locusts were strategically blinded or a specific nerve was severed that controlled whether or not the locusts felt the biting of other locusts, Couzin concluded that without these two abilities that contributed to cannibalistic tendencies, locusts could not swarm or migrate in proper or efficient form.

Another experiment that Couzin executed was to test what content of salinity in water the Mormon crickets preferred.  In this, Couzin discovered that the crickets were most attracted to water with the same salinity level as their blood.  This further confirmed his discovery of cannibalistic tendencies of insects that swarm.

This discovery is being called “The Forced March,” which implies that the insects must constantly move forward in the direction of the swarm and also have aggressive behavior in order to avoid being the victim of cannibalistic insect swarm tendencies.

Another group that Couzin largely studied in his lecture were fish.  Couzin said he would put fish into tanks and stimulate through light projection other entities in the tank such as predators or prey of the particular fish so that he could observe how the patterns changed in real life situations.

Not only did he look at the schools of fish as a whole, but he also mapped the directions of which each fish was travelling and compiled this data to form the first ever interactive network of the “collective mind.”

As a result of his research, Couzin said he has developed conclusions about how groups of organisms make decisions concerning factors such as leadership and the power dynamic in these groups. ..

Couzin discerned that if the minority of an informed section of a group of organisms has stronger instincts than that of the majority and the uninformed population of the sample, then the minority actually wins out in a decision.  However, this becomes increasingly difficult as the number of uninformed subjects is increased.