Ever watch a group of ants transport a morsel of food much larger than themselves? There’s obviously teamwork involved in the difficult task of getting the crumb to the nest.
Now we know many more fascinating details about how the tiny insects work as a team, thanks to a study carried out by researchers from the departments of physics of complex systems and chemical physics at the Weizmann Institute of Science in Rehovot, Israel.
In research published July 28 in the journal Nature Communications, physicist Ofer Feinerman and his colleagues describe how a balance of individual direction and conformist behavior enables ants to work together to get their food home in the right direction.
Using video analysis to track the movements of ants in a group, the scientists observed that in order to lug an object too big for one ant to move, several ants surround it. The back ones lift, while those on the leading edge pull, working in synchrony to bring the crumb to their nest.
The more ants around the item (in this case, a breakfast cereal nugget), the faster they can move it. However, although the bit of food always travels in the general direction of the nest, the ants make some wrong turns and need to correct their course.
This is accomplished through an amazing process of taking turns, sort of like an athletic team switching out one player for another on the bench.
When new ants join the effort, the other carriers automatically follow the newcomers’ lead for about 10 to 20 seconds, steering the object so that the trajectory becomes better aimed toward the nest. Then those ants become confused as to the proper direction, and they defer to the next set of newcomers.
The art of ant communication
The chemical physics group, under the direction of Prof. Nir Gov, made a mathematical model to illustrate this cooperative behavior.
According to the model, the decisions of the “non-informed” carriers fit an intermediate level of behavioral conformism, whereas the “well-informed” individuals take the role of optimally steering the direction of the load.
This model describes a critical point between conformism and individuality that enables the group of ants to coordinate their work and adjust their direction as needed.
Feinerman said this study can teach us much about the role of individuality within a group of social animals. “In this system, the wisdom does not come from crowds. Rather, some individuals supply the ‘brains’ and the role of the group is to amplify the ‘muscle power’ of savvy individuals so that they can actually move the load.”
His Ant Collective Behavior Group employs many different methods to analyze ants’ cooperative skills and efficiency.
“Dropping to your knees for a closer look may prove to be counterproductive: interactions are too many to grasp, individual ants are difficult to follow, and when one finally manages to focus on one — she often appears to be somewhat disoriented,” Feinerman writes.
“Such characteristics describe much of the biological world as it is composed of dense, communicating, and difficult-to-understand ensembles. In our lab, we combine experiments with theory, lab with field work, technological solutions with data analysis, and pencil scribbling with nest digging to try and take on the challenging task of observing ants.”