“I know of no occupation in which more zeal and important service can be rendered to a country than by improving agriculture,” opined George Washington in a 1794 letter. While the prevalence of frontier farming has declined since Washington’s time, agriculture itself is arguably one of humanity’s most important achievements, laying the foundation for the rise of civilization and enabling the human population to multiply exponentially.
However, agriculture is not necessarily a uniquely human endeavor. Leafcutter ants, each with brains no bigger than a pinhead, have also passed from hunter-gatherers to farmers—and did so long before humans ever existed.
As far as ants are farmers, it’s because, along with a select few other species, they grow their own food for consumption. Currently, more than 200 ant species across the Western Hemisphere are making forays into the jungle, driven by a deep-seated atavistic instinct that forces them to harvest plant material, which is carried back to the nest to feed fungal crops, which are in turn consumed by the ants.
According to a 2017 study by the Smithsonian Institution, ants have been cultivating different fungi in the South American rainforest for about 60 million years. Using the genomic data of several ant species, the study found that there was a divergence within agricultural ant lineages about 30 million years ago, due to some ant species moving to drier climates.
Farmer ants practice two types of cultivation: higher and lower agriculture. In lower agriculture – which is usually found in humid rainforests – fungal crops are able to escape the ant colonies and return to the wild. The ants sometimes collect the wild fungi to bring back to their nests. This allows the gene pools of wild and cultivated fungi to intermingle, with the result that the lower ants have less influence on the genetics and evolution of their crops. Essentially, the fungus can survive without them, and this means that it is less dependent on the ants.
In higher agriculture, neither the ants nor the fungus are able to survive on their own. According to a Smithsonian press release on the study, about 30 million years ago, when the climate in South America shifted to cooler, arid grasslands, some ants colonized the new landscape outside the forest. The fungus, which evolved in the rainforest, was no longer able to escape and survive in the desert, effectively isolating it into another species that depend on the ants and are unable to exist alone in the wild. The ants dig chambers up to 12 feet below the ground, altering moisture and airflow to create the ideal greenhouse for their crops.
“If you’ve been carried to a dry habitat, your fate will match the fate of the colony you’re in. At that point, you’re bound in a relationship with those ants you weren’t attached to when you were in a wet forest entomologist and lead author Ted Schultz said in the press release.
Over time, the fungus, which could not survive in arid climates without the fungal greenhouse built by the ants, was domesticated. “Like some crops that have been so modified by human breeders that they can no longer reproduce and live independently in the wild, some fungal species have become so completely dependent on their relationship with farm ants that they can never be found on their own again. . from their farmers,” Schultz said in the release.
The feeling is mutual
However, the inexorable interplay between insect and fungus is more layered. When ants became farmers, they lost the ability to make an amino acid, arginine. So they had to depend on the fungus for that amino acid. In return, the ants provide water, cleanse and take care of the fungus. This begs the question, what is the real puppeteer? Have the ants controlled the fungus to their advantage, or are they the ones kept in check, toiling out of necessity for amino acids—to maintain the prosperity of their fungal masters? The answer is neither. What they have developed is a mutualistic relationship, with both species benefiting from harmonious synchronization.
The ant farmers build advanced, climate-controlled underground labyrinths and formulate fungal foods with selective nutrients, allowing them to increase fungal production without sacrificing crop resilience to environmental threats. They secrete antibiotics to prevent fungal pathogen growth, and they evolve with the local ecosystem to achieve similar controls and balances. Their agriculture provides all the food needed for their societies at a scale and efficiency that rivals human agriculture. All this ensures a stable food supply without causing ecological carnage.
Contrast this with some modern farming practices, which involved farming cut down forest, steel tractors and chemical pesticides at the expense of biodiversity and environmental health. While we cannot directly copy the blueprints of ant farming, we can learn to coexist better with other species and adopt more sustainable farming practices. Ultimately, we want to sustain the planet’s rapidly growing human population without leaving a trail of polluted ecosystems and deforested wastelands in our wake.