The Magic of Herding

Summary

When Doyle Ivie, a 77-year-old farmer and sheepdog trainer in northern Georgia, received an email from Saad Bhamla and Tuhin Chakrabortty, two biophysicists from the Georgia Institute of Technology, he was intrigued. The researchers wanted to know if he would let them record the to-and-fro-ing of his sheepdogs. The farmer couldn’t fathom what the scientists might learn about the abstractions of physics by studying his muddy canines, but he agreed. Not long afterward Bhamla and Chakrabortty, who study collective behavior, pulled up to Ivie’s farm to watch the dogs in action. That day, the farm was hosting a sheepdog trial, a centuries-old competition in which sheepdogs show off their herding skills by steering small flocks of sheep across a field, as well as splitting the group, known as “shedding,” among other tasks.Physicists have studied sheepdog herding for decades, but they have mostly modeled how the dogs gather up large herds, Bhamla says. In these large herds, sheep display what’s known as selfish flocking behavior, gravitating toward the center and putting others between themselves and danger. But in smaller groups, as in sheepdog trials, their decisions become more erratic, as they waver between following the flock or heading off on their own. How the sheepdogs manage to get the sheep to go where they want under these chaotic conditions suggests a solution to a tough problem in physics—controlling noisy, unpredictable collectives, which is relevant not just to sheep, but also to drone and robotic swarms and pedestrian movements, among other things. Such emergent collectives are driven by both group-level patterns and by interactions between individual members of the group. ADVERTISEMENT Nautilus Members enjoy an ad-free experience. Log in or Join now . Instead of suppressing randomness, they found, the sheepdogs seemed to embrace it.“Dogs do amazing things, so naturally we were interested,” says Bhamla. After their visit to the farm, Bhamla and Chakrabortty...