Ants have outpaced humans as experienced ‘farmers’, and, according to a study published in the journal Science, these insects have been cultivating their own food for 66 million years, long before humans evolved as a species.
Sixty-six million years ago, an asteroid struck the Earth, triggering a global mass extinction, but creating favorable conditions for the development of fungi, which the surviving ants used to feed themselves after the catastrophe.
To reach this discovery, a team of scientists from the Smithsonian National Museum of Natural History (United States) obtained genetic sequences from samples of 475 different species of fungi (288 of which are cultivated by ants) and 276 different species of ants (208 of which cultivate mushrooms).
With all this data, they developed an evolutionary chronology showing that ants and fungi have been linked for 66 million years, roughly since the asteroid collided with the Earth at the end of the Cretaceous.
This collision filled the atmosphere with dust and debris, which blocked the Sun and hindered photosynthesis for years, causing the extinction of about half of all plant species on Earth at that time.
However, this catastrophe proved an opportunity for the fungi, which proliferated by feeding on the abundant dead plant matter that covered the soil.
“The dinosaurs didn’t fare very well at the end of the Cretaceous, but the fungi had an apogee,” said one of the authors, Ted Schultz, an entomologist at the Smithsonian who spent 35 years studying the evolution of ants.
The researchers believe that the fungi that proliferated during this period fed on decomposing foliage, bringing them into close contact with the ants.
These insects, in turn, took advantage of the abundance of fungi for their food and continued to depend on them as life recovered from the extinction.
The new work also reveals that the ants took another 40 million years to develop a more advanced agriculture: cultivating fungi for food for about 27 million years.
“Ants domesticated these fungi in the same way humans domesticated crops,” emphasized Schultz.
In South America, for example, the researchers believe that the ants removed fungi from the humid forests and carried them to drier areas, isolating them from their wild ancestral populations.
Once isolated, these fungi would have become completely dependent on the ants to survive in the arid conditions, laying the foundations for the superior agricultural system now practiced by leaf-cutter ants.
The researchers organized nearly 250 species of fungus-growing ants from the Americas and the Caribbean according to the four agricultural systems they use.
The leaf-cutter ant is among those practicing the most advanced strategy, known as superior agriculture: they harvest pieces of fresh vegetation to sustain their fungi, while these fungi produce food for the ants.
