In the absence of a better option, join the bandwagon

Threatened ants stop and aggregate in the absence of exit routes

We see it everyday, and it is undeniable as it is obvious. Consumers using the most popular of all the anti-bacterial soaps, and an advertisement for a toothbrush that is used by "8 out of 10 dentists". In view of competitions where no product pose a comparative advantage over the others, consumers generally pick the most popular one. The "bandwagon effect" in business is often to the advantage of established companies whose products and services have been known and trusted for years.

Analogous systems in social sciences have been studied and quantified in recent years. In the field of network analysis and social dynamics, the tendency to associate oneself to the most popular individual in the network is explained by Barabasi and Albert in 1999 [1]. They coined the term "preferential attachment" to describe the growth of scale-free networks with power-law degree distributions. Since then, a burst of papers on network theory describing real-world networks that employ preferential attachment mechanisms have come out in literature, providing evidence as to the extent of its applicability to model social systems.

In our work [2], we explained how bandwagon effects can be manifested by a group of insects, who have no capability to recognize the existing paradigm and the current majority. Black garden ants (Lasius niger) were threatened when they are taken from their natural environment and confined to move inside a circular dish. The new environment is surrounded by water and hence presents no possibility for escape.

Ten ants were released to the enclosure, their motion captured by video. The ants at first scanned through the entire area in search for exit routes. But as it becomes evident that escaping is impossible, ants stop and instead look for the other ants, forming a static herd. Video processing indicates a sharp decline in ant speed after 100 frames, roughly corresponding to 3 seconds after they have been released. This time indicates the relaxation time, at which the static herd emerges.

"The gradual stopping of the ants in searching for a way out is an indication of selfish individualistic intentions," the paper notes. "When no escape is possible, the most logical choice, even for ants, is to prioritize individual safety over group benefit. Joining the group in a herd increases this sense of security. Eventually, majority of the ants will realize this benefit, paving the way for a common collective choice of stopping and staying at one place."

The interesting fact is that herding in this case evolved instantaneously, with no particular agent (in this case, ant) being initially "famous" to pave the way for collective action. The bandwagon emerged as individual ants independently chose to be together by instinct. "In the absence of better options, in this case escape routes, these individualistic tendencies give rise to coordinated group effort," the paper succinctly concludes.

1. Barabási, A.-L., Albert, R. (1999). "Emergence of scaling in random networks". Science 286: 509-512.
2. Roxas, R.M., Batac, R., Longjas, A. and Monterola, C. (2008). "Emergence of static herding in the absence of an escape route for wandering ants" accepted for presentation in the 26th Samahang Pisika ng Pilipinas Congress.