What Mice Do When You’re Not Looking

24/7 trackers give researchers insight into how mice mate, form social hierarchies, and more. Behold the rodent equivalent of 'Big Brother.'
Tambako the Jaguar

Turns out Americans aren’t the only ones getting spied on lately. By hooking up groups of mice with precise trackers, researchers have gotten a closer look at how societies form. At least in mice, the answer is: fast.

Weizmann Institute scientists introduced mice fitted with tracking chips into a square, 4-meter pen lined with video cameras. The scientists recorded the mice’s movements 30 times a second for up to months at a time. (It’s fun to imagine there were little mouse-propaganda posters advertising the Ministry of Truth or something, but alas, probably not.)

The researchers, unsurprisingly, gathered a lot of data from the voyeurism: they learned when the mice ate and drank, when they slept or fought, and more. Eventually, the team could determine whether each mouse was an introvert or extrovert, and could even predict, with more than 90 percent accuracy, how the mice would mate.

Here’s the really intriguing part: With varied personality types inside the pen, the mice eventually bowed down to a dominant mouse in just 24 hours. By that point, they’d even developed a class system based on personality type. That was done with a group of “normal” mice. By including mice genetically inclined toward shyness, the researchers got a very different result: the mice didn’t pick a leader, and when they did, the leader was quickly overthrown.

Why is this sort of experiment significant? Because it’s not simple to track an animal society (or a human society) with such granular detail. This experiment shows it’s possible, at least for small animals running around a small space.

The study was published in the journal Nature Communications.