The collective action of ants makes all kinds of things possible.
Ants have no explicit system of organisation. No government, no formalised chain of command. Despite terms like “queen” and “worker,” no one ant give other ants orders. One ant, on its own, is pretty dumb. But together they know how to form colonies that work with remarkable efficiency—there wouldn’t be 10 billion billion (yes, two billions) ants in the world otherwise.
But how? The principle is emergence, as Kurzgesagt explains in this overview of how many parts can add up to a whole that not only bigger, but smarter, and wildly different from its component parts.
Ants in particular self-organise through scent. Because different ants with different jobs emit different smells, ants can figure out if there aren’t enough ants on food patrol, for instance, by recognising that they haven’t smelled a food ant in a while. Then, they change their job. This can be called a “adaptive self-organising system,” and it’s not unlike talking to your neighbours and finding out the neighbourhood gossip.
Ant decision making is vastly different than most other animals, their single-minded focus an ability to change has made them world-conquerers. An anthill resembles basic human building techniques, but ant architecture is best understood like human skin, constantly regrowing. Their movements can even emulate strange states of matter. Together, they can resemble a liquid. Perhaps not surprisingly considering that liquids are likewise comprised of billions of individual molecules. In that way, ants and water are like nature itself: more than the sum of its parts.