Passino, K. P., T.D. Seeley and P. K. Visscher. 2008. Swarm Cognition in Honey Bees. Behavioral Ecology and Sociobiology; Vol. 62(3): 401-414.
Swarm Cognition in Honey Bees
Thomas Seeley’s lab at Cornell University has been studying honey bees for close to three decades, unraveling the complex and fascinating social dynamics of bees and hive life. If you are unfamiliar with the process of hive selection in bees, you will be amazed by its complexity as well as the similarities of swarm dynamics with the democratic process and, as Passino et al. argue in this paper, with neural processes used for decision making in vertebrate brains.
In late spring or early summer, when a hive becomes overcrowded the queen bee and about half of her workers (we’re talking thousands of bees) will leave the mother-hive and go out in search of a new home (the remaining workers stay in the mother-hive and produce a new queen). This swarm of emigrating bees travel about 100 feet before forming a beardlike cluster dangling from a tree branch. Several hundred of the oldest bees go off to scout for a new home. The search and selection process is fascinating and rather democratic. Scout bees go off individually checking every hole, crack and crevice within a 30 square mile area. They scrutinize each potential hive carefully by walking its inner surfaces, gathering information to help them assess its quality as a future hive. When a scout has found a candidate hive, it flies back to the swarm and performs its “waggle dance” on the bodies of other bees on the swarm. During the waggle dance, the scout runs along the bodies of bees on the swarm while wagging its body back and forth (a "waggle run"), then it turns and runs back to its starting point and repeats the waggle run. The waggle dance communicates two essential pieces of information: the quality of the hive (the more waggle run circuits repreated in a waggle dance, the higher the quality of the candidate hive) and the location of the candidate hive (the direction of the walk indicates the direction of the candidate hive and the length of the walk indicates the distance to the hive. Wow.). Not surprisingly, the more waggle runs included in a waggle dance, the more it stimulates other bees to do that dance and to scout out that hive themselves. Now, you have to visualize dozens of scouts communicating their candidates to the hive (via the waggle dance) during the same period of time. These dances will likely be of varying vigor and frequency depending on the individual scout’s assessment of the quality of the hive (i.e. how excited they are about the hive they found). “Undecided” scout bees continue to observe and respond to the most frequent and vigorous waggle dance by going to scout that candidate themselves and return to do their own waggle dance communicating their assessment of quality. You can imagine the potential for exponential growth in waggle dances for high quality sites and the relatively quick decline in waggle dances for low quality sites. Once a quorum of scouts favoring a particular site is reached (as indicated by number of scouts at that site) then the scouts return to the swarm and begin communicating to the rest of the bees to prepare for the move.
It is easy to see how the process for selecting a new hive parallels many aspects of the democratic process. Swarm members receive information about many hive candidates, and based on that information choose and campaign for their preferred candidate. The "winning" candidate is selected once enough members of the swarm agree on one candidate. Of course, like any election, they do not always select the best candidate and there are many opportunities along the way for the decision-making to steer away from the best candidate. This whole process is complex and I have only provided the broad strokes. Nonetheless, when people refer to their minds as being like a swarm of bees they clearly do not realize that a swarm of bees is actually incredibly organized and efficient. In fact, if our brain were to act like a swarm of bees, it would actually be working in much the same way as…our brain! Passino et al. (2008) make a compelling case for swarm cognition, the notion that the way the swarm processes information for hive selection shares many features with the decision-making brain processes of individual vertebrates. In the simplest sense (and it gets much more complex), think of each bee as a neuron, the group of bees as a neural population, the waggle dance is the neuron firing (action potential), and the bee-to-bee communications is the neural network and communications, and short-term memory is the spatially distributed information or group memory. The analogies between the way the brain and the swarm process information go much deeper than this, however, it becomes pretty technical and unless you are familiar with neuroscience it will not have much meaning, so I'll stop here.
What does this all mean? Of course, for scientists studying swarms and colonies it means that they can look at developments in neuroscience as a lens through which to better understand swarm dynamics. But to me, it is just plain cool to imagine a swarm of bees interacting in much the same way as the population of neurons in our brains. Also, as someone who enjoys thinking about the ultimate (in an evolutionary sense) explanation for things, it leads me to ponder if selection pressures on general decision making processes are similar, whether on an evolutionarily-tightly-bound group of individuals (like a colony of closely related bees, who share many genes) or on the neurons involved in the decision making processes of a single individual. Very cool.
Gail Farmer is an ornithologist, naturalist and PICE Director of Programs. Although she hasn't been involved in ecological research in five years, she likes to peruse the scientific literature just for the fun of it.
If you are a scientist and have research you would like to communicate to an audience of naturalists, please send a summary of your work to Gail (gfarmer AT piceweb.org) for inclusion in the next Science News for Naturalists column.
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