Meerkat Matriarchs Are Selfish Street Crossers
Why did the meerkat cross the road? To get to the other side. How did the meerkat cross the road? Like a chicken.
From flocks of migrating birds to human friends on a road trip, lot of animals travel in groups. When they run into trouble during these trips, they'll often change their formation so they can better deal with the problem and keep themselves safe. When a flock of sheep encounter a predator, for example, they clump together, and each individual sheep tries to move towards the center of the group and away from the vulnerable edges, while the group collectively moves away from the threat. In the same situation, elephants form a defensive circle around the calves while the matriarch of the group inspects the threat and may charge at it. Alpha male baboons likewise take up a position at the edges of their groups when moving through dangerous areas in order to protect more vulnerable individuals.
What if the danger to the traveling party isn’t the same old predator that’s been hunting a species for thousands or millions of years, though? What if it's a relatively new threat, like man-made roadways? To find out, Simon Townsend, who studies animal communication and cognition at the University of Zurich, looked to meerkats.
These members of the mongoose family are highly social and live in groups of up to 50, led by a dominant mating pair. They deal with predator attacks from both land and air, and deploy subordinate group members as sentries to keep watch while the group forages. In South Africa’s Kalahari Desert, they also have to contend with roads that cut through their territories.
Meerkat groups are matriarchal, so the alpha female runs the show and leads the group on foraging trips and burrow excavations and in conflicts with other meerkat groups. Given their importance in the group, Townsend figured that these females would be wary of the danger that roadways presented. Specifically, he predicted that even given the novelty and recent appearance of the roads, the matriarchs would position themselves deep within the group to maximize their own safety while crossing.
After periodically watching different meerkat groups at the road over the course of a year, Townsend found that while the alpha female usually started at the front of the group in the walk to the road, more than half the time they dropped back into the middle of the group and let one or more subordinate females go first as they crossed. When the lower-ranking females were at the front of the group to begin with, they tended to stay there when crossing the road. Using this data, Townsend created computer simulations of meerkat crossings that allowed him to quantify the shuffling of positions that happened at the side of the road, and found that the dominant females were about 40 percent more risk averse than the other females.
Chimpanzees, Townsend points out, also change their behavior in response to the danger posed by roads. While crossing, the alpha male and other high-ranking males usually take up exposed positions at the front and rear of the group so they can scan the road or keep an eye on all the other group members. In the way they handle a road crossing, both these meerkats and chimps are showing off their mental flexibility, applying and adapting old behaviors to new threats.
In comparison to the chimps, who take up more vulnerable positions that allow them to protect the group, the meerkat matriarchs’ retreat to the middle of the group seems selfish. It’s still for the good of the group, though: The matriarchs are the core of the meerkat social structure, and when they die, groups have been known to completely break down and disperse, leaving lone animals to fend for themselves. Being a wimp and moving in the middle of the pack reduces both the risks to themselves and to group stability.