Aristotle was right about ants being political animals. By some standards, the most successful of those political animals are the Argentine ants, because they have become the biggest political society on Earth, as measured both by the global extent of their territory and the number of members in their supercolony. Trillions of individual Argentine ants belong to one supercolony found on every continent except Antartica (Whitfield 2024).
A Four-Minute Animated Video on the Argentine Ant Supercolony
A Twelve-Minute Video on the Argentine Ant as a Dominant Species
One reason for the political success of the Argentine ants is that their colonies are what Mark Moffett (2010; 2012) calls "anonymous societies," in which group members are distinguished from outsiders based on shared cues--chemical signaling through a colony-specific odor--rather than individual recognition. In contrast to the social insects, almost all nonhuman vertebrates live in "individual recognition societies," which means that the number of members in each society must be small--typically no more than about 150 at most--so that members can recognize one another individually. Argentine ants and human beings are the only animal species that have naturally evolved with the capacity to organize societies with hundreds of millions or even billions of members (Griffin 2011).
Aristotle was also right in seeing that while human beings live in large, anonymous societies like the ants, human beings are more political than other political animals because human beings have a unique capacity for symbolic thought, so that social membership in human societies is communicated symbolically, rather than communicated chemically as it is for ant societies. If this arose early in human evolution among our prehistoric hunter-gatherer ancestors, then perhaps my list of twenty natural desires should include a natural desire for membership in a symbolically identified anonymous society.
Lockean liberal globalists might say that the lesson we should learn from the Argentine ants is the need for an open borders immigration policy. But then the nationalist conservatives could say that the real lesson here is that we need ethnic restrictions on immigration to enforce the ethnic nationalism that satisfies our natural desire for ethnic identity.
Or should we rather say that it is foolishly anthropomorphic to draw any moral lessons for human politics from the social life of ants, which commits the naturalistic fallacy in falsely inferring moral values for humans from the natural facts of ant life?
ARGENTINE ANT SUPERCOLONIES
The Argentine ant (Linepithema humile) is native to the lowland areas of the Parana River drainage in northern Argentina, Uruguay, Paraguay, and southern Brazil. They were first identified by Austrian entomologist Gustav Mayr who found them in the area of Buenos Aires in 1866. Here the Argentine ants wage territorial battles with other ant species. When they win the battles, they can raid the enemy nest and eat the ant brood. But in Argentina, their opponents fight well enough to preserve their species from extermination. It's a different story, however, when the Argentine ants become an invasive species in countries around the world, where they can wipe out most of the native species of ants (Moffett 2010; 2012).
Shipping trade out of Buenos Aires was probably the cause of the introduction of Argentine ants into other regions of the world because they travelled as stowaways on the boats. They appeared first on Madeira Island (in the Atlantic southwest of Portugal and Spain) in 1882. They were first recorded in New Orleans in 1891. Then, around 1907, they were seen in California, around the San Francisco Bay and Los Angeles. They could have arrived in a railway car from the southeastern United States. They were discovered in New Zealand in 1990 and in Japan in 1992.
There are now four supercolonies of Argentine ants in California. Within each supercolony, the members are not aggressive towards one another, even when they have never previously encountered one another individually, but they aggressively attack any ants belonging to another supercolony. In the area around San Diego, the Very Large Colony and the Lake Hodges Colony are constantly at war along their borders. It is estimated that over thirty million ants die each year along a battlefront that is many miles long. This might be the largest battlefield on the Earth (Moffett 2010).
As the name indicates, the Very Large Colony is indeed the largest supercolony in California--stretching over 620 miles from the Mexican border to San Francisco with over a trillion members. In Europe, the largest supercolony extends over 1240 miles from Italy to the Atlantic coast of Spain.
Researchers have collected live Argentine ants from the supercolonies in North America, Europe, Asia, Hawaii, New Zealand, and Australia. Worker ants from different supercolonies were randomly selected and put together in pairs to see if they would show aggression towards one another. They found that workers from the largest dominant supercolonies in these six parts of the world showed no aggression towards one another, but they were aggressive towards ants from the secondary smaller supercolonies. Thus, the largest Argentine ant supercolonies throughout the world behave as if they are members of one transcontinental megacolony (Sunamura et al. 2009; van Wilgenburg et al. 2010).
With trillions of members on six continents, this global society of Argentine ants is the largest animal society on the Earth, even exceeding some of the largest human societies (such as China and India, each with about 1.4 billion people).
How is this possible? The primary explanation is that the populations of these ants in this globally distributed supercolony possess similar genetic and chemical profiles, and consequently they treat one another as members of the same colony, while aggressively attacking those ants that belong to other colonies.
The minimal condition for any society is that the individual members must identify themselves as a group by seeing each other as similar and outsiders as different. To make this distinction between us and them, they must have some shared label or sign of their identity. For humans, this label of recognition of group identity might be a national flag, a common language, or a shared national history. For ants, it's the odor of their colony produced by the cuticular hydrocarbon molecules on the exoskeleton of each ant. Researchers have identified specific chemicals in the cuticular hydrocarbons of Argentine ants that identify those ants who are members of the colony (Brandt et al. 2009). Ants are cooperative with those ants who have the odor of the colony. But they aggressively attack those ants who have the unfamiliar odor of a foreign colony.
An Argentine ant in the San Francisco Bay area who is a member of the Very Large Colony could be transported 600 miles to the Mexican border and dropped into a Very Large Colony nest, and she would treated as a regular member of the colony. But if she were dropped into the nest of the Lake Hodges Colony around San Diego, she would be killed.
Another reason for the seemingly boundless growth of the Argentine ant colony has to do with its breeding system. All ants form colonies with one or more egg-laying females (queens) and a large number of sterile females (workers). The smallest colonies have one queen and a few workers. But most ant colonies have one or a few queens and tens of thousands of workers. A few species can have colonies with hundreds of thousands of queens and many millions of workers. A mature colony rears winged sexual females and males that can fly to mate in midair, often with a few winged males from other colonies; and then each queen drops to the ground to dig a nest and begin brooding sterile workers. This new colony will have its own distinctive scent, even differing from the queen's birth colony.
Argentine ants are different, however, because their queens never fly away. The queens move on foot between nest chambers spread throughout the territory of the colony. They lay eggs within the same colony with the same scent. A big supercolony of Argentine ants can have millions of queens spread out over a huge territory that continually expands, while remaining the same colony.
Some ant experts--particularly, Deborah Gordon of Stanford University--deny that Argentine ants live in supercolonies: "In fact, there is no functional super-colony of Argentine ants, no single giant colony stretching for miles, much less across the globe" (Gordon 2010). She argues that a supercolony cannot truly be a single colony because the ants "cannot possibly meet and thus cannot possibly share resources or interact ecologically" (Gordon and Heller 2012).
But I agree with Mark Moffett's argument that as long as the Argentine ants in a supercolony accept one another as members and reject outsiders that satisfies the minimal criterion for being a society (Moffett 2012; 2019: 77).
What--if anything--can the Argentine ants teach us about human societies? I will take up that question in my next post.
REFERENCES
Brandt, Miriam, Ellen van Wilgenburg, Robert Sulc, Kenneth Shea, and Neil Tsutsui. 2009. "The Scent of Supercolonies: The Discovery, Synthesis, and Behavioural Verification of Ant Colony Recognition Cues." BMC Biology 7:71.
Gordon, Deborah. 2010. "Colonial Studies." Boston Review, September 13.
Gordon, Deborah M., and Nicole E. Heller. 2012. "Seeing the Forest and the Trees." Behavioral Ecology 23:934.
Griffin, Nicholas. 2011. "Before the Swarm." The Atavist, March.
Moffett, Mark. 2010. Adventures Among Ants: A Global Safari with a Cast of Trillions. Berkeley: University of California Press.
Moffett, Mark. 2012. "Supercolonies of Billions in an Invasive Ant: What Is a Society?" Behavioral Ecology 23: 925-933.
Moffett, Mark. 2019. The Human Swarm: How Our Societies Arise, Thrive, and Fall. New York: Basic Books.
Sunamura, E., X. Espadaler, H. Sakamoto, S. Suzuki, M. Terayama, and S. Tatsuki. 2009. "Intercontinental Union of Argentine Ants: Behavioral Relationships Among Introduced Populations in Europe, North America, and Asia." Insectes Sociaux 56: 143-147.
Whitfield, John. 2024. "Ant Geopolitics." Aeon, February 16.
van Wilgenburg, Ellen, Candice W. Torres, and Neil D. Tsutsui. 2010. "The Global Expansion of a Single Ant Supercolony." Evolutionary Applications 3: 136-143.
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