Are humans the only animals that caucus? Any animal living in a group needs to make decisions as a group. Species ranging from primates to insects have methods for finding agreement that are surprisingly democratic.
Primates, our closest relatives, have provided lots of material for researchers. Scientists have seen gibbons following female leaders, mountain gorillas grunting when they’re ready to move and capuchins trilling to one another.
Sometimes the process is more subtle. A group may move across the landscape as a unit without any obvious signals. Researchers have found that any baboon might start moving away from the others as if to draw them on a new course — male or female, dominant or subordinate. When multiple baboons moved in the same direction, others were even more likely to come along. When there was disagreement, with trailblazing baboons moving in different directions, others would follow the majority. But if two would-be leaders were tugging in directions less than 90 degrees apart, followers would compromise on a middle path.
As meerkats start each day, they emerge from their burrows and begin searching for food. Each meerkat forages for itself, digging for bugs and other morsels, but they travel in loose groups, each animal up to about 30 feet from its neighbors, said Marta Manser, an animal-behavior scientist. Nonetheless, the meerkats move as one unit, drifting across the desert.
The meerkats call to one another as they travel. One of their sounds is a mew that researchers refer to as a “move call.” It seems to mean, “I’m about ready to move on from this dirt patch. Who’s with me?” Scientists have found that only about three group members had to mew before the whole party decided to move along.
African wild dogs
Like pet dogs, African wild dogs spend some of their time socializing and some of it lazing around. Members of a pack jump up and greet one another in rituals called rallies. After a rally, the dogs may move off together to start a hunt — or they may go back to resting. That decision, researchers said, seems to be democratic.
To cast a vote for hunting, the dogs sneeze. The more sneezes, the more likely the dogs were to begin hunting. If a dominant dog started the rally, the pack was easier to persuade — just three sneezes might do the trick. But if a subordinate dog started the rally, it took a minimum of 10 sneezes.
When a colony divides, a queen and several thousand workers fly away from a hive together. The swarm finds a place to pause while a few hundred scouts search for a new home. When a scout finds a promising hole or hollow, she inspects it. Then she flies back to the swarm and does a waggling dance that tells the other bees about the site — its quality, direction and how far away it is.
More scouts return to the swarm and do their own dances. Gradually, some of the scouts become persuaded by others, and switch their choreography to match. Once every scout agrees, the swarm flies off to its new home.
Rock ants, which live in stony crevices throughout Europe, use a caucuslike method to choose a new home.
Some rock ant scouts seem to be always on the lookout for better homes, said Nigel Franks, an emeritus professor at the University of Bristol in England. These scouts investigate the quality of potential new nest sites. If enough scouts find themselves at the same site, they’ll reach the minimum number needed to relocate the colony. They can also try to build such a quorum by going back to the original nest and recruiting other ants to follow them. They lead these ants one at a time, a follower tapping a leader with her antennae to stay on course.
Either way, once a critical number of ants have gathered at one new site, the colony’s decision is official. The ants aren’t quite patient enough to let the electoral process take its course, though. They bring over the rest of the colony by simply picking up their sisters and hauling them to their new home.