‘Big Brother’ Study Sheds Light On Social Hierarchy In Mice

By Aya Ephrati, NoCamels July 10, 2013 Comments

Whether it’s a small tribal society or a nation of millions, there’s always some sort of hierarchy in human culture. But hierarchy is not solely the domain of humans. Many animals, such as mice, display distinct social hierarchy.

A unique experiment conducted by Doctor Tali Kimchi of the Weizmann Institute monitored mice 24/7 in a “sort of mouse version of the television show Big Brother,” to reveal  some unusual insight into the behavior that enables social hierarchies to form.

Kimchi says that the system developed by her team to study the mechanisms that regulate social behavior in animals may be especially useful to understand the social aspects of human disorders such as schizophrenia and autism. 

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Big Brother is watching

Different strains of mice were placed in the “house,” a four square meter pen, and allowed to go about their lives with no intervention from the human team. To automatically track them, each mouse was implanted with an ID chip. Video cameras and infrared lighting (to allow nighttime filming) were also placed throughout the area.

The combined chip-location reporting and continuous video footage allowed the system to keep tabs on each individual mouse and the team was able to identify dozens of individual behaviors. This allowed them to discern social behaviors such as seeking out specific companions for activities or rest, avoiding certain individuals, attacking others, and more.

By sorting out behavioral patterns, the automated system that the researchers developed was able to differentiate between the various genetic strains of the mice in the group and predict mating patterns with over 90 percent accuracy. The surveillance system became so adept at sorting the mice, that it was able to point out “autistic” mice – ones that exhibit little social engagement and ridged behavior patterns.

King for a day

These close observations also revealed how one individual attained dominance over the group. In a paper that appeared in Nature Communications, Kimchi and her team described the emergence of a dominant leader and the development of a class system in a group of normal mice within a 24-hour period.

In further experiments, the more social mice were replaced with the autistic group. This led to dramatic differences in social interaction and hierarchy building. With the autistic group for example, no mouse leader emerged, or if one did, he was quickly overthrown.

The system that the researchers developed, along with the results of the various experiments, are leading to new conclusions about how behavioral problems can affect individuals within a society as well as how they affect the formation of social structures within a society.

Kimchi’s research team consisted of Aharon Weissbrod, Genady Wasserman and Alex Shapiro, as well as Dr. Ofer Feinerman of the Weizmann Institute’s Physics of Complex Systems Department.

Photo: Mouse by Bistock

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