Adventures Among Ants - Mark W. Moffett [149]
THE THIRD WAY: THE ANT COLONY AS AN ORGANISM
Many ancient peoples likened their settlements to the anatomy of the human body. The Greeks reformulated this view as the body politic, a likeness between the body and the state, and from these comparisons the idea of the superorganism was born.17 While the bedlam of modern human societies can make the idea of a body politic seem strained, an ant colony does often seem to act as an individual, once you get to know it. I have detected differences in temperament between marauder ant societies, with one nest appearing more aggressive or hardworking than another. Researchers have trained whole colonies of the British ant Leptothorax albipennis to be more proficient at migrating to new nests: the workers learn collectively, after repeated practice, perhaps in part by improving their individual performances and in part by interacting more effectively with their fellows.18
Some parallels to organisms are easy to see: ant colonies can be like human bodies, composed of nonreproducing workers that sustain the whole (equivalent to the somatic cells that compose the organs of the human body, such as the lungs and the heart) and a permanent reproductive queen that produces the next generation (like the human body’s ovaries and testes).19
Still, people who see the resemblance between ant and human societies often find the similarities between a colony and an organism less apparent. Certainly a colony is a kind of individual, in the same way that a university is one entity even when it occupies many buildings. But most of us think of an organism as an integrated being with a body of a specific size and shape. A colony, which may seem nothing more than a scattered assemblage of ants, lacks this feature—but then so do organisms such as mats of fungi or ivy, which grows in a rambling manner and, as it turns out, reproduces flexibly—budding flowers here and there something like an Argentine ant colony with its ongoing production of new queens.20
It’s easiest to grasp the likeness of an ant colony to a simple organism, such as a freshwater Volvox, which contains up to fifty thousand cells arranged in a sphere that can reach the size of a small ant. Some of the cells are big and capable of reproduction, but the majority of them are tiny and sterile. These sterile cells, like worker ants, collaborate to transport nutrients and work dynamically as a team, much as marauder ants do around prey, to move the sphere toward or away from light. Smaller and simpler still, because it has no differentiated sexual cells—or any other clear labor specialization—is the species Eudorina elegans, another swimming organism that is able to perform most of the same coordinated activities as Volvox, and even, like an ant colony that develops as the workers gradually emerge, goes through a simple embryonic transformation.21
Volvox and Eudorina are composed of just one or two cell types, but the human body is made up of more than two hundred varieties of cells. Complexity—usually measured by this kind of division of labor—generally increases as size increases, whether the organisms in question are individuals composed of cells or societies made up of ants. Most small colonies, like the Acanthognathus nests I collected in Costa Rica, have a single worker type, but a marauder ant colony, reaching a much greater size, contains a number of worker castes, including categories differentiated by both size and age. Similarly, while people in a nomadic hunter-gatherer society are essentially nonspecialists, today even a midsized town has dozens of job descriptions, and Manhattan has hundreds. The more jobs there are, the more the members of a society begin to function like tissues in a living organism, by being assembled into social networks and work groups.
Why is this so? For a small organism or group, specialization is typically unnecessary, and it might even be dangerous: with excessive division of labor, a few deaths could wipe out all the specialists, leaving jobs undone.