There are some 20 quadrillion ants living in the world today. Science writer John Whitfield offers an essay at Aeon on the factors underlying the successful spread of vast colonies from, say, South American to Europe — by piggybacking on human journeys.

Whitfield, author of Lost Animals: The Story of Extinct, Endangered and Rediscovered Species (Welbeck 2020), resists the temptation to compare ant dominance to human dominance of the globe, in part because, well, ants think differently. Here are a couple of the questions he answers in his sparkling and informative essay:

Why do ants work so well together?

Recognition looks very different for humans and insects. Human society relies on networks of reciprocity and reputation, underpinned by language and culture. Social insects – ants, wasps, bees and termites – rely on chemical badges of identity. In ants, this badge is a blend of waxy compounds that coat the body, keeping the exoskeleton watertight and clean. The chemicals in this waxy blend, and their relative strengths, are genetically determined and variable. This means that a newborn ant can quickly learn to distinguish between nest mates and outsiders as it becomes sensitive to its colony’s unique scent. Insects carrying the right scent are fed, groomed and defended; those with the wrong one are rejected or fought.

John Whitfield, “Ant geopolitics,” Aeon, February 16, 2024

As Eric Cassell notes in Animal Algorithms: Evolution and the Mysterious Origin of Ingenious Instincts (2021) , all species of ants are social; there are no known solitary ants.

How different is ants’ way of thinking?

The more I learn, the more I am struck by the ants’ strangeness rather than their similarities with human society. There is another way to be a globalised society – one that is utterly unlike our own. I am not even sure we have the language to convey, for example, a colony’s ability to take bits of information from thousands of tiny brains and turn it into a distributed, constantly updated picture of their world. Even ‘smell’ seems a feeble word to describe the ability of ants’ antennae to read chemicals on the air and on each other. How can we imagine a life where sight goes almost unused and scent forms the primary channel of information, where chemical signals show the way to food, or mobilise a response to threats, or distinguish queens from workers and the living from the dead?

Whitfield, “Ant geopolitics”

Cassell suggests that colony communication is somewhat like a computer algorithm: The ant processes pheromones (scent signals) as if they were AND gates and STOP in a computer system (p. 91). Thus, the ant is not judging the situation and deciding whether to go along with the group or not — as a human might — but rather, processing a signal. Stanford entomologist Deborah M. Gordon calls the resulting communication without personal understanding the “anternet.”

In closing, Whitfield tells the story of Biosphere 2, a giant terrarium in Arizona, designed in the 1980s as a self-sustaining living system with no connection to the outside world. Developed to test the design of biospheres for space exploration, it fell victim in 1996 to the southeast Asian black crazy ant, which turned it into a honeydew factory.

So sometimes, sheer numbers and a viable social algorithm win out over high individual intelligence. But, in fairness, the eight humans who lived inside Biosphere II for two years did not seem to enjoy it much:

You may also wish to read: Do ants think? Yes, they do — but they think like computers. Computer programmers have adapted some ant problem-solving methods to software programs (but without the need for complex chemical scents). Navigation expert Eric Cassell points out that algorithms have made the ant one of the most successful insects ever, both in numbers and complexity.

and

How do insects use their very small brains to think clearly? How do they engage in complex behaviour with only 100,000 to a million neurons? Researchers are finding that insects have a number of strategies for making the most of comparatively few neurons to enable complex behavior.