I can’t say I’ve ever thought twice about picking my friends, family, and even my acquaintances out in a crowd. But what about other species? How do animals living in large social groups tell each other apart?
Kimberly Pollard and Daniel Blumstein, from UCLA’s Department of Ecology and Evolutionary Biology, asked themselves the same question. While previous research has confirmed that highly social species exhibit unique contact calls, Blumstein and Pollard were interested in pushing the question further. They asked whether the size of a social group is the evolutionary driver of individuality.
Their six year study was conducted on eight species of sciurid rodents (members of the squirrel family), belonging to social groups of various sizes. They analyzed members of each group for the individuality of their contact calls. The results will be featured on the front cover of the March 8 issue of Current Biology.
Picking an individual out of a large group can be difficult, yet it is vital to group dynamics. Animals must be able to recognize a mate, parent, offspring, individual of higher social rank, or rival, so they know where to divert their energy. That’s a lot of individuals to know. And while it may seem ironic that bigger social groups yield a larger variety of contact calls among members, that’s exactly what Pollard and Blumstein found.
Animals in large impersonal groups such as a school of fish or swarm of insects — which have relatively unstable group membership — do not necessarily benefit from individuality. However, a tight-knit group of sciurids, often made up of closely related kin, may offer preferential treatment to family members that can only be distinguished by a distinct contact call.
For example, offspring must be discernible in order to receive food from a parent. A mate might be chosen as a result of its unique contact call. It’s no wonder large groups have high degrees of individuality — animals need to know who to trust and who to avoid. For instance, group members can recognize alarm calls that trigger an anti-predator response. Members that provide consistent warnings about predators are not only more trusted, but can also move up the sciurid social ladder based on this reliability factor.
So what are the implications of this study for humans? We don’t have problems distinguishing our family and friends from strangers. That being said, our social networks grow in tandem with our fast-paced lifestyles, and the boundaries of our once tight-knit groups are dissipating. Could this create an unnatural evolutionary pressure on the human species to develop higher degrees of individuality?
It’s hard to say. Members of the rodent family can’t wear clothes or cut their hair like we can. However, according to the researchers, the results could reveal why seven billion unique people can exist all over the world. At one point or another, it was far more beneficial to maintain individuality than to simply blend in with the crowd.
