Picture a troop of olive baboons, moving over the savannah. There’s around fifty of them, and they cover a lot of ground as they search for grass, seeds, insects, and other bits of food. They need to stick together so they don’t get eaten, but different animals might want to head in different directions at any one time. How do they coordinate their choices to preserve the sanctity of their group? As primate researcher Joan Silk says, “It’s hard enough to get two adults and two kids into the car at the same time let alone 50 baboons who can’t talk.”

It’s a fairly simple question—how do animals make decisions as a group?—but it’s also incredibly hard to answer, even for