Adventures Among Ants - Mark W. Moffett [99]
Their scouring behavior illustrates the repetition and fast tempo that are the hallmarks of large ant societies. We saw this with the swarms of marauder ants that crisscross the terrain within a raid, rooting out prey (and weaver ants do much the same in much looser bands). An advantage to having many do the same thing at once is that if one individual fails to finish a task, whether subduing prey or building a trail, another will do it.37 Also, the frenetic workers in large societies often make mistakes; close inspection may reveal one ant going the wrong way or leaving building material at an inappropriate site. Such a blunder might be lethal for a solitary creature that has but one chance to do a job right; the same may be true for ant nests with few individuals, in which workers carry out every move with meticulous care. But in a large society, differences in performance assure that often enough a task is done to perfection. Even if lapses or errors occur, they are quickly corrected by another individual. In fact, with sufficient redundancy, variations in performance can lead to useful novelty and innovation, as when an ant on a busy recruitment trail overshoots the intended prey and, while she is lost, happens on another; or when a friendly competition for goods and services brings a kind of market economy to a nest.
The redundancy of worker actions gives a superorganism other survival advantages as well. While a human life ends if a wound destroys the brain or heart, the functions of brain and heart are spread throughout a colony, making it harder to damage. To bring the comparison to the level of the society, we humans have erected increasingly elaborate top-down hierarchies and centralized systems of control to deal with the disasters, from plagues to terrorism, that so easily disrupt our modern nations.38 The lesson from nature, however, is that the war on terror will never end: all living things fight back against enemies (parasites, predators, and competitors) in a continual arms race in which new defenses emerge but the dangers never disappear because the adversary always evolves a counterstrategy. Under such circumstances, it doesn’t pay to consolidate power; better to have redundant operations with few or no established chains of command, as ants do.39 Because they have no central command center that can malfunction or be crippled or manipulated by outside forces—indeed, no established leaders or unique individuals—the destruction of part of the population will never bring down the whole.40 Weaver ants apply this redundancy even to their nests by having multiple leaf tents instead of a vulnerable central domicile. With the exception of reproduction (most colonies succumb to the death of the queen), this safety net permeates all aspects of ant social existence.41
Is there an ideal size for individual workers within the superorganism? The answer is unclear—as it is for the size of the cells in the body, for that matter. One weaver ant major worker can stretch across the nail of a pinkie finger. Among ants, that’s pretty large. Weaver ants compete with other dominant ants that have much smaller workers. But imagine a mature weaver ant colony that, instead of being polymorphic, contained only minor workers, and instead of half a million ants, held several million. The colony consisting only of minors would burn more energy at rest than the original colony or a colony of only large workers of the same total weight—perhaps an economic disadvantage; and no minor worker could hold prey as large as one major can restrain for long enough for reinforcements to arrive. But the foragers would exchange information at a higher rate and be more effective at rooting around in locations previously hidden to them; and the greater number of individuals would be more effective at ganging up against the competition.
Variation in worker size is associated with a division