Humans simply invented agriculture some 10,000 years ago, but ants have been doing it for millions of years. New analysis indicates that, although ants operate farms in many situations, true-life domestication resulted 30 million years ago, in desert or near-desert conditions.
Attine ant species form a symbiotic relationship with fungi. The six-legged farmers propagate the fungus, provides for nutrients and protection from other swine that might eat it more recklessly. In return, they get to eat the fungal growth.
Like bakers’ apprentices taking precious starter dough to determine their business, attine ants carry a small amount of fungus when they found a brand-new settlement. As with human agriculture, this has shaped the genetics of the species they farm, since varieties of fungus that best suit attine needs are more likely to be farmed.
Smithsonian Museum entomologist Dr Ted Schultz compared the DNA of 119 ant species, 78 of which are farmers. reporting his findings in Proceedings of the Royal Society B. He mapped the timing of when species diverged, applying fossils for proof, to pinpoint those closest to the stem of the ant farmers’ family tree.
The 250 known species of fungus-farming ants are divided into those that rule what is called “lower” and “higher” agriculture. Lower agriculture applies fungal species that can live without the ants’ shield. Sometimes the fungus will spread beyond the settlement to grow in the wild, becoming a resource for the ants to draw on if their harvests fail.
Higher agriculture involves fungus that, like many human harvests, have been so modified by the farmers as to be unable to survive independently. Since the ants cannot subsist without their fungi, the two species are locked in reciprocal dependence.
Lower agriculture has previously been estimated to have begun in South America 55-65 million years ago. Schultz’s work indicates higher agriculture dates back around 30 million years and began in a dry climate, belying previous hypothesis of a wet origin.
Global climatic changes at the time dehydrated much of South American out. Suitable ranges for rainforest fungi would have contracted, and Schultz thinks some were saved by ants that provided them with reliable moisture, accumulating ocean for humidity-controlled fungal gardens.
“These higher agricultural-ant societies have been practising sustainable, industrial-scale agriculture for millions of years, ” Schultz said in a statement. “Studying their dynamics and how their relationships with their fungal partners have evolved is available through important lessons to inform our own challenges with our agriculture practices. Ants have established a kind of agriculture that renders all the nourishment needed for their societies applying a single crop that is resistant to disease, pests, and droughts at a magnitude and degree of efficiency that rivals human agriculture.”
Given our own disastrous experience with monocultures, we’ve much to learn.
Ted Schultz( left) and Jeffrey Sosa-Calvo( right) trench a lower fungus-farming ant nest in the seasonally dry Brazilian Cerrado( savanna ). Photo credit: Cau Lopes.The underground garden-variety enclosure of a primitive, lower fungus-farming ant settlement. Higher agriculture settlements are larger. Cau Lopes/ Ted Schultz/ Smithsonian
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