According to the study published in the journal Proceedings of the Royal Society B, ants from the Attine group were farming fungi as a food source. The initial finding was made in 2009 after a primitive fungal garden was unearthed in the Brazilian Cerrado, making it the earliest case of ant farming. The ants, reports the Daily Mail, had created underground farming systems that allowed them to grow, harvest and maintain fungi. Ants and fungi had formed a mutually beneficial relationship wherein the ants propagated and defended the fungi from other animals, and the fungi in turn would be eaten by the ants.
Today, about 250 ant species continue the practice in tropical forests, grasslands and deserts throughout the Americas. Lead author and Entomologist Ted Schultz has said: “If you had X-ray vision and you could look out in a wet, new-world tropical forest, you’d see the entire underground just peppered with garden chambers.” (Related: Ants have been domesticating cultivated crops for 50 million years, research reveals.)
Though Schultz and his team found that fungus-farming ants most likely came from the same ancestors in South America, two different farming ant societies would eventually emerge. “Lower” agriculture ants, based mainly in tropical forests, would care for fungi that were able to thrive even without assistance from the ants. “Higher” agriculture ants, located primarily in areas with dry climates, had cultivated fungi that were completely dependent on their farmers.
This divergence, Schultz believes, happened approximately 30 million years ago when the planet was cooling and dryer areas began to arise. The arid climate had produced conditions suitable for ant farmers to domesticate the fungi in underground gardens. “They’re already kind of putting their fungal crops in greenhouses,” Schultz has said, “but if you’re in a dry habitat, even if your fungal crop could escape, there’s nowhere to go.”
These ants, it was found, were capable of carefully maintaining the humidity and controlling the temperature of their subterranean nurseries. On this, Schultz has remarked: "If things are getting a little too dry, the ants go out and get water and they add it. If they're too wet, they do the opposite. If you've been carried into a dry habitat, your fate is going to match the fate of the colony you're in. At that point, you're bound in a relationship with those ants that you were not bound in when you were in a wet forest."
It was also found that the ants weeded out any fungi that attempted to eat what they had grown. Customs like these are what helped the ants sustain their fungus gardens for 15 to 20 years despite the gardens largely being monocultural.
“These higher agricultural-ant societies have been practicing sustainable, industrial-scale agriculture for millions of years," Schultz has said. "Studying their dynamics and how their relationships with their fungal partners have evolved may offer important lessons to inform our own challenges with our agricultural practices. Ants have established a form of agriculture that provides all the nourishment needed for their societies using a single crop that is resistant to disease, pests, and droughts at a scale and level of efficiency that rivals human agriculture.”