Adventures among Ants. Mark W. Moffett

grasping it in her jaws. If she joins a group, however, she places her forelegs on the burden, then presses her head against its surface, jaws open, but she does not use her jaws to grip unless she can hold on to a projection such as a limb. She walks with her remaining legs as she and her nestmates transport their load.

      With modest colonies of a few thousand, Daceton ants in Venezuela have developed only rudimentary cooperation in the transport of food. Here two workers have pulled so persistently in conflicting directions that the moisture has been wrung out of this caterpillar. Flies sneak in to drink from the oozing meat.

      What about this technique makes marauder ants excel at gang retrieval? Picture several people hefting a box by thrusting upward, not only with the palms of their hands but with their foreheads as well. By pushing a load up, forward, and against each other, the clustered ants balance the weight effectively among themselves. Army ants use a different technique, lining up to straddle a burden under their bodies rather than encircling it. Either way, the groups cancel the rotational forces that solitary porters contend with when they lift a burden in front of them. Anyone who’s felt a heavy box twist out of his hands has experienced this force, a problem that disappears when another grasps the object on the other side.¹⁰

      While participating in a lift-and-carry operation, each of the marauder ant “porters” performs a slightly different task. As when several people haul a piano, an ant’s movements depend on where she is located relative to the direction of motion. Workers at the forward margin walk backward, pulling the burden. Those on the trailing edge walk forward, apparently pushing it. Ants along the sides shuffle their legs sideways and slant their bodies in the direction of travel. The ants sort out their roles during a few minutes of turmoil, then whisk the item off with effortless grace. When a media worker joins in at the front or back ends of large booty, she appears to be adept at guiding the group around obstructions or through shifts in the trail course, performing another valuable role in the transport team.

      BUT IS IT TEAMWORK?

      Should we consider these groups teams? Dictionaries define the word team as a group organized to work together, which could apply to many social situations among ants. Although in many team sports there is a set roster for each game, with ants, under most circumstances, the participants change and are interchangeable.¹¹ We saw this for raids: marauder ants come and go while the quarry is being subdued, and similarly to and from the raid as a whole. By comparison, transport groups are more stable, though ants may leave or join a group when, for example, an object becomes snagged, at which point the participants must sort out their movements relative to each other afresh.

      Often, members of human teams divide the labor, doing different things at once to get the job done. Although ant workers cannot recognize each other as individuals in the way human teammates do, many marauder ant activities—among them killing prey, attacking alien ants, and maintaining trails—probably conform to the American football model.¹² In some cases, different worker castes play specific “positions” and concentrate on distinct tasks, as when minors hold down prey while medias and majors shear its limbs. In other situations, all participants belong to the same worker caste and show flexibility in how they do their jobs, as when minor workers perform differently in the transport group depending on where they are located around the prey.

      One species of wood ant shows the ultimate division of labor in a transport team, with a degree of leadership exceptional among ants. Among Formica incerta, common in New England fields, when a successful forager can’t move an item of food herself, she attracts ants in the vicinity or recruits some from the nest. Unable to assess the size of her find, she may not gather a suitable number of individuals. If not enough helpers arrive and she needs to leave to find more, those already on scene—even if they have already started carrying off her find—will wander away as if the food weren’t there. Only the original food finder can keep the team motivated, and only she can go for more help. She must be present to guide the transport team from start to finish. Outside her role with this particular meal, of course, there is nothing special about her. If she is later recruited by another scout, she goes to work as a regular worker, while the individual who located the food becomes the supervisor for its retrieval.¹³

      Several years ago in El Salvador I watched workers of the army ant Eciton burchellii chop a scorpion to pieces. I could see that the workers fell into different positions as the transport groups came together, but they didn’t adopt behaviors specific to teamwork. This occurred because the media workers had trouble lifting an unwieldy hunk of the tail. Then one of the less common but bigger and stronger “submajor” workers arrived and was able to straddle it in the classic army ant manner and start it moving. Immediately one of the smaller medias crowding around was able to fit into the cramped space under the abdomen of the bigger ant, where she grabbed the scorpion’s stinger, which was trailing on the ground. Thereafter the two functioned, as they often do in this species, as a team, with the forward ant doing the power lifting and steering, while the little one kept the back of the prey from dragging. Meanwhile, the scorpion’s body was being carried by four ants: the same pairing of a submajor and a media handled the main axis of the corpse, with two more medias off to the side, helping lift the scorpion’s appendages.¹⁴

      A “submajor” Eciton burchellii army ant hefting a chunk of centipede while a smaller media worker behind her lifts its dragging end. The minor worker lying below them in a pothole along the route serves as “living road fill.”

      The workers of small ant societies seldom show such collaborations, even of the accidental kind typified by army ants. Being dependent on individual initiative to get things done, each worker is likely to do fine on her own, often aided by special tools, such as trap jaws. Marauder ants serve well as an example of a large society in that the workers are more likely to complete tasks by toiling together or by sharing information with other specialists by means of the language of complex ant societies—chemical communication.

      Humans are in some ways similar. Anthropological studies have shown that small groups of hunter-gatherers tend to be labor generalists, with everyone having the ability to be self-sufficient or near to it and pulling his or her weight with a wide range of work (beyond some sexed-based differences). In larger human societies and with increasing urbanization, a complex division of labor in which individuals have limited employment skills becomes more prevalent—as it is for workers in many ant species with large colonies too. This pattern has been understood in humans since 1776, when a Scot, Adam Smith, founded modern economics with his book Wealth of Nations. Smith saw specialization as necessary to the growth and development of societies because of the productivity resulting from each laborer’s skill at his job and the reduction of time lost in switching between jobs.¹⁵ But Smith also saw in this specialization the tragic “mental mutilation” of laborers, a decline in intellect from the repetition of menial tasks that he claimed must be countered by management from the state.

      This deficiency can be observed for large ant societies as well, in which specialized workers are incapable of accomplishing much without the cooperation of nestmates.¹⁶ A lone marauder ant is as hopeless as the urban sophisticate who, as in the movies City Slickers and Romancing the Stone, is dropped into a remote environment where he’s incapable of caring for himself. In contrast to the simple interactions between individuals in ant species with small colonies, however, marauder ants show synergy in spades—not only at the emergent level of entire raids, but also more intimately, in the coordination of smaller, local teams. Group transport of food may be the most vivid example.

      Synergy and faithfulness to the whole, not independence, are integral to the functioning of the most well-integrated organisms, just as they are with their social counterpart, the superorganism. A sponge, for example, though clearly an organism, is so simple that its cells often survive for a day or two when forcibly separated from the whole and can reunite to form a new sponge, whereas the cells in spilled human blood or a severed finger will perish, and usually in fast order.

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