Ants Have Been Farming Fungus for 50 Million Years

Introduction: an agricultural tradition far older than ours

An underground mystery tens of millions of years in the making

Did you know that the first agriculture on Earth was not invented by a human civilization, but by tiny social insects living beneath our feet for tens of millions of years? Long before our ancestors learned to sow wheat or domesticate cereals, colonies of fungus-farming ants in South and Central America had already perfected a complete agricultural system, complete with crop selection, meticulous upkeep, and protection against pests. This story, documented in studies published in the journal Science, thoroughly upends the notion that agriculture is an exclusively human invention.

The principle is as simple as it is ingenious: these ants, often grouped under the name attine ants, harvest fragments of leaves, flowers, or other plant matter, chew them, then deposit them in specially built underground chambers. On this organic substrate grows a cultivated fungus, a living pantry for the colony. This is no accident or occasional occurrence: it is a stable system, passed down from generation to generation, with entire colonies organized around this food production. The sheer sophistication of this organization still surprises the entomologists who study it closely today.

A discovery that redefines the very notion of agriculture

What makes this story so fascinating is just how old the phenomenon is. According to genetic analyses reported by institutions like the Smithsonian, this practice dates back roughly 50 to 60 million years, long before the appearance of the human species itself. By comparison, human agriculture, with the domestication of wheat and barley in the Near East, only dates back around 12,000 years. The gap is staggering: ants have a head start of several million years over us when it comes to organized food production, making this one of the oldest examples of agricultural management documented anywhere in the living world.

Researchers studying this phenomenon, particularly through resources documented by Nature on insect agriculture, stress that this system did not freeze in time. It evolved, diversified, and gave rise to several lineages of farming ants with slightly different strategies. Some species cultivate fungi still capable of surviving in the wild, while others, more specialized, depend almost entirely on their colony to reproduce — a sign of domestication pushed to the extreme. This gradual progression, spread across tens of millions of years, shows just how evolution can build complex systems through small successive steps rather than a single dramatic leap.

What makes the comparison with human history even more striking is the sheer scale of specialization involved. Just as human farmers gradually moved from generalist subsistence plots toward highly specialized monocultures, certain ant lineages abandoned their ability to survive on any food source other than their cultivated fungus. This one-way evolutionary path, difficult to reverse once fully established, illustrates how deeply intertwined the fate of two species can become once a stable agricultural relationship takes hold across countless generations.

How this underground garden really works

Meticulous, demanding gardeners

Contrary to a simplistic image of ants randomly stacking leaves, colonies of fungus-farming ants practice constant, rigorous upkeep of their crop. Specialized workers continuously inspect the fungal garden, remove contaminated parts, adjust humidity, and regulate the temperature of the underground chambers. There is even weeding-like behavior: the ants actively eliminate parasitic molds and unwanted fungi that could compete with their main crop. This sanitary monitoring never stops, day or night, without a moment's rest for the colony.

This attentive management strangely echoes the most careful human farming practices. The most advanced colonies, such as those of the genus Atta, can number millions of individuals organized into specialized castes — some dedicated exclusively to harvesting fresh vegetation, others to grinding and fertilizing the substrate, and others still to sanitary protection of the garden against pathogens. This division of labor reflects a remarkable degree of social organization in service of a single goal: guaranteeing a stable, abundant food supply for the entire colony, sometimes for decades on end.

A relationship of mutual dependence between two species

This system only works because the ants and their fungi evolved together, in a reciprocal relationship known as coevolution. The cultivated fungus provides the colony with a rich, predictable food source, while the ant provides the fungus with a protected environment, free of competitors and parasites, along with dispersal to new territories when young queens leave the original nest to found a new colony.

Some species of fungi cultivated by ants may have even lost, over time, their ability to survive without the intervention of their insect hosts. This degree of interdependence is comparable to what we observe between humans and certain domesticated plants, which can no longer reproduce effectively without human intervention. This functional kinship between the two agricultural systems, human and insect, continues to fuel fascinating research into the evolution of animal behavior and the blurry boundaries between instinct and learned strategy.

What recent genetic studies reveal

Retracing half a billion years of evolutionary history

Advances in modern genetics have allowed researchers to reconstruct, with unprecedented precision, the family tree of fungus-farming ants and their associated cultivated fungi. By comparing the DNA of multiple species of ants and cultivated fungi across tropical America, scientific teams have been able to establish precise timelines, confirming that this insect agriculture emerged gradually, through several stages of increasing specialization.

This work, published in Science, revealed a cascading diversification: as certain lineages of ants became more specialized in fungus farming, their partner fungi also evolved, sometimes losing independent capabilities in exchange for greater efficiency within the nest environment. This kind of intense coevolution is rare in the animal kingdom and represents a textbook case for evolutionary biologists around the world, illustrating just how two very different organisms can end up becoming nearly inseparable from one another.

One of the oldest known domestication relationships

Scientists often describe this ant-fungus relationship as one of the oldest forms of domestication documented on our planet. It's a strong term, but a justified one: this is indeed an active selection, repeated over millions of generations, which has shaped the characteristics of the cultivated fungus to make it ever better suited to the needs of the colony that farms it.

This finding has implications that reach far beyond the field of entomology. It invites us to rethink the very definition of agriculture, detaching it from the idea of an exclusively human invention to instead consider it an evolutionary strategy among others, capable of emerging independently in different species facing similar survival challenges and the need for a stable food supply. Such convergence, observed in a group of insects so distant from us, forces us to reconsider the exceptionalism we usually grant to the human species.

Why this discovery fascinates scientists so much

A lesson in humility about human exclusivity

For a long time, agriculture was presented as one of the fundamental markers of human progress, a pivotal step that enabled the development of settled civilizations. The discovery that insects were practicing a form of agriculture far older and just as sophisticated forces us to nuance that narrative. This shift in perspective is probably the most stimulating part of this story: it reminds us that biological ingenuity does not necessarily follow the path we imagine, and that nature explored solutions comparable to ours long before we ever appeared.

This realization also fuels broader reflection on evolutionary convergence, the phenomenon by which very different species develop similar solutions to similar problems, without any direct kinship. The fact that social insects independently developed a system comparable to human agriculture illustrates the power of this convergence when environmental and social conditions allow for it — a useful reminder that evolution often recycles the same good ideas across very distant branches of the tree of life.

Concrete applications for modern science

Beyond the purely fascinating aspect of this discovery, researchers see real scientific potential in studying fungus-farming ants. Understanding how these insects manage to cultivate a single fungus for millions of years, without a widespread epidemic or a collapse in production, could inspire new approaches to biological control against fungal diseases in human agriculture itself.

The mechanisms ants use to control parasitic molds, notably through antimicrobial secretions produced by certain symbiotic bacteria living on their bodies, are of particular interest to microbiologists. These natural substances, refined by millions of years of selection, could one day inform research into new antifungal compounds, in a context where resistance to conventional chemical treatments is becoming a growing concern for global agriculture and food security worldwide.

A diversity of strategies across the Americas

From giant colonies to tiny nests

Not all fungus-farming ants practice their agriculture on the same scale. Some species live in modest colonies, numbering only a few hundred individuals tending a small fungal garden. At the other extreme, the most advanced species, such as the leafcutter ants of the genus Atta, can build gigantic underground nests, spanning several square meters and housing millions of workers organized into highly specialized castes.

This diversity of strategies reflects millions of years of adaptation to varied environments, ranging from dense tropical forests to the more arid zones of Central America. Each lineage has refined its own method of harvesting, transporting, and managing the plant substrate, proving that insect agriculture, far from being a uniform phenomenon, has diversified almost as much as human agriculture across cultures and regions of the globe. This might be the detail that strikes me most: nature did not settle on a single good way to farm, but on dozens, each finely tuned to its own environment.

What this diversity teaches us about evolution

The existence of multiple variants of this insect agriculture, at different degrees of sophistication, gives scientists a kind of natural laboratory for observing the successive steps that led to the most advanced domestication. By studying the least specialized species alongside the most advanced, researchers can reconstruct a complete evolutionary scenario, from the first opportunistic associations between ants and fungi to the highly integrated agricultural systems observed today.

This comparative approach confirms that domestication is not an isolated event but a gradual process, punctuated by multiple reciprocal adjustments between the two partner species. A valuable lesson which, according to several biologists, could also shed light on how human agriculture itself diversified from initially rudimentary practices — a parallel that continues to fuel passionate debates between biologists and anthropologists about the very nature of technical progress.

What makes this comparative work especially rich is the sheer geographic range covered by fungus-farming ants, from the humid lowlands of the Amazon basin to drier scrublands further north. Researchers cataloguing these lineages have noted that even neighboring colonies, separated by only a few kilometers, can show measurable differences in how they manage their fungal gardens, hinting at an ongoing process of fine-tuned local adaptation that is still unfolding today rather than a finished evolutionary product frozen in place millions of years ago.

By Maxime Marquette, columnist

Sources

Primary sources

Science — research on the coevolution of fungus-farming ants and their cultivated fungi

Smithsonian Institution — resources on agriculture among social insects

Nature — thematic collection on insect agriculture

Secondary sources

National Geographic France — reports on animal behavior

Futura Sciences — science news on the planet and living world

Sciences et Avenir — science news and analysis