Mice in Three-Way Relationships

What effect does a constant stream of engaging stimuli have on our relationships? On our social structure as a whole? What percentage of our actions is influenced by others, and how does this translate, at some point, into group behavior?

Neurobiologists Prof. Alon Chen and Dr. Elad Schneidman of the Weizmann Institute and their team members have been using mice to investigate these questions. Chen and Schneidman approach the group as a network composed of the joint behavior patterns of mice that had had their fur dyed in bright, glow-in-the-dark colors. Among other things, this enables the researchers to apply mathematical analyses related to complex networks to uncovering the basic structure of mouse society. (Dr. Tali Kimchi, who experiments with the “Big Brother” setup we wrote about in June uses a very similar experimental setup: a large, semi-natural enclosure for groups of mice and 24-hour tracking of their movements. But Kimchi takes as her starting point the individual traits that feed social structures, while Chen and Schneidman begin with the interconnected patterns of the social structure, itself, and go on to disentangle the natural interactions between mice.)

Tracking fluorescent mice

For example, their analysis showed that, for a group of four mice, about one quarter of their actions – i.e., visiting a particular feeding, sleeping or other station within the enclosure at any point in time – could be attributed to the locations of the other mice. This collective effect was much larger than would be expected from simple relationships between pairs of mice (which was what the researchers had thought they would find). Most networks (including, for example, nerve networks in the brain) can be described in terms of interactions between pairs of nodes; yet mouse group behavior had a strong component of irreducible, three-way relationships.

The researchers then took groups that had spent some of their “youth” in a more complex environment, comparing them with control groups that had had the standard compliment of feeding and sleeping stations. The social networks of the mice in the more complex environment flattened out – pair relationships were making a much larger contribution to the social structure.

Chen and Schneidman compare the stimulus-rich environment to a wealthy society, suggesting that the easy life may reduce an individual’s reliance on the social structure for survival. Alternately, they say, the wealth of choices might actually encourage more aggression and less cooperation – leading to a predominance of paired interactions.

What does this say about human society?  This Weizmann science writer would suggest that the findings can provide a framework for thinking about our social groupings. For example, as opposed to feeding stations, many of the stimuli we encounter in our modern lives are based on interpersonal connections of some sort. Might our ubiquitous social media be simultaneously flattening the complex structure of our society, at the same time that they broaden it? And, since humans are probably closer to sheep than to mice when it comes to the influence of the group on individual actions, will new inventions that compete for our attention or otherwise affect our personal relationships have a relatively large or small effect on group behavior?

ps-- To any Jewish readers -- Shana Tova. Hope you find some time this year for those messy, complex, interpersonal relationships -- even if it does mean dinner with the whole family.