“I do not know of any activity in which more zeal and important service can be rendered to a country than by improving its agriculture,” said George Washington in a letter from 1794. While the prevalence of the frontier farmer has admittedly diminished since the days of Washington, agriculture itself is arguably one of the crowns of humanity, laying the foundations for the rise of civilization and allowing the human population to proliferate exponentially.
However, agriculture is not necessarily a purely human endeavor. Leaf-cutter ants, each with brains no bigger than a pinhead, also went from hunter-gatherers to farmers – and they did long before humans even existed.
Since ants are farmers, it is because they, along with a few other selected species, grow their own food for consumption. Currently, more than 200 species of ants across the Western Hemisphere make forays into the jungle, driven by a deep-rooted atavistic instinct that compels them to harvest plant material, which is brought back to the nest to feed the fungal cultures, which are in turn eaten by the ants.
According to a 2017 study from the Smithsonian Institution, ants have been cultivating various fungi in the South American rainforest for about 60 million years. Using genomic data from different ant species, the study found that a divergence occurred within agricultural ant lineages around 30 million years ago, a result of the movement of some ant species to drier climates.
Farm ants practice two types of culture: upper and lower agriculture. In lower agriculture – which typically occurs in tropical rainforests – fungal crops are able to escape ant colonies and return to the wild. Ants sometimes collect wild mushrooms to bring them back to their nests. This allows the genetic pools of wild and farmed fungi to mix and therefore the lower ants have less influence over the genetics and evolution of their crops. Essentially, the fungus can survive without them, which means it is less dependent on ants.
In higher agriculture, neither the ants nor the fungus are able to survive independently. According to a Smithsonian press release on the study, about 30 million years ago, as the climate in South America shifted to cooler, drier grasslands, some ants colonized the new landscape outside of the forest. The fungus, which grew in the rainforest, could no longer escape and survive in the desert, effectively isolating it from a different ant-dependent species, unable to exist on its own in nature. Ants dig chambers up to 12 feet underground and alter the humidity and airflow to create the ideal greenhouse for their crops.
“If you’ve been transported to dry habitat, your spell will match the spell of the colony you’re in. At this point, you are bonded in a relationship with those ants that you weren’t related to when you were in a rainforest, ”entomologist and lead author Ted Schultz said in the press release.
Over time, the fungus, which could not survive in dry climates without the mushroom greenhouse built by the ants, domesticated. “As with some crops that have been so heavily modified by human herders that they can no longer reproduce and live on their own in the wild, some species of fungi have become so completely dependent on their relationship with agricultural ants that they cannot never live independently. of their farmers, ”Schultz said in the statement.
The feeling is mutual
However, the inexorable interaction between the insect and the 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 this amino acid. In return, the ants water, cleanse, and feed the fungus. This begs the question, who is the real puppeteer? Did the ants control the fungus to their advantage, or are they the ones that are controlled, out of necessity working for amino acids – keeping their fungal masters thriving? The answer is neither. What they have developed is a mutualistic relationship, where the two species benefit from harmonious synchronization.
Ant breeders build sophisticated, climate-controlled underground mazes and formulate mushroom foods with selective nutrients, allowing them to increase mushroom production without sacrificing the crop’s resilience to environmental threats. They secrete antibiotics to prevent the growth of fungal-threatening pathogens, and they evolve with the local ecosystem for similar checks and balances. Their agriculture provides all the food their societies need on a scale and efficiency that rivals human agriculture. Through all of this, they ensure a stable food supply without inflicting ecological carnage.
Juxtapose this with some modern farming practices, where agriculture has involved leveled forests, steel tractors, and chemical pesticides to the detriment of biodiversity and environmental health. While we cannot directly copy ant breeding plans, we can learn to coexist better with other species and adopt more sustainable farming practices. Ultimately, we want to be able to support this planet’s burgeoning human population without leaving a trail of polluted ecosystems and deforested wasteland in our wake.