Study claims ants were farming 66 million years before humans

By Stephen Beech via SWNS

Ants were farming more than 60 million years before humans first planted crops, according to new research.

Insect agriculture began 66 million years ago in the aftermath of the devastating asteroid impact that doomed the dinosaurs, say American scientists.

Several species have been growing their own food since long before humans evolved as a species, according to a new study published in the journal Science.

Researchers from the Smithsonian’s National Museum of Natural History in Washington, DC, assembled and analyzed a massive genetic database.

They say colonies of ants began farming fungi when the massive asteroid struck Earth 66 million years ago.

The impact caused a global mass extinction, but also created "ideal" conditions for fungi to thrive.

'The researchers say innovative ants began cultivating the fungi, creating an evolutionary partnership that became even more tightly intertwined 27 million years ago and continues to this day.

The Smithsonian team analyzed genetic data from hundreds of species of fungi and ants to craft detailed evolutionary trees.

Comparing the trees allowed the researchers to create an evolutionary timeline of ant agriculture and pinpoint when ants first began cultivating fungi.

Lead author Dr. Ted Schultz, the Museum’s curator of ants, said: “Ants have been practicing agriculture and fungus farming for much longer than humans have existed.

“We could probably learn something from the agricultural success of these ants over the past 66 million years.”

He says nearly 250 different species of ants in the Americas and Caribbean farm fungi.

Researchers organized those ants into four agricultural systems based on their cultivation methods.

Leafcutter ants are among those that practice the most advanced strategy, known as higher agriculture.

Dr. Schultz says those ants harvest bits of fresh vegetation to provide sustenance for their fungi, which in turn grow food for the ants called gongylidia.

This food helps fuel complex colonies of leaf-cutter ants that can number in the millions.

Dr. Schultz has spent 35 years studying the evolutionary relationship between ants and fungi, and has conducted more than 30 expeditions to Central and South America to observe the interaction in the wild.

He has also reared colonies of leafcutter and other fungus-farming ants in his lab at the museum.

Over the years, Dr. Schultz and his colleagues have collected thousands of genetic samples of ants and fungi from across the tropics.

He said: “To really detect patterns and reconstruct how this association has evolved through time, you need lots of samples of ants and their fungal cultivars."

The researchers used the samples to sequence genetic data for 475 different species of fungi - 288 of which are cultivated by ants - and 276 different species of ants, 208 of which cultivate fungi.

It was the largest genetic dataset of fungus-farming ants ever assembled, allowing the researchers to create evolutionary trees of the two groups.

Comparing wild fungal species with their cultivated relatives helped the team to determine when ants began utilizing certain fungi.

The data revealed that ants and fungi have been intertwined for 66 million years, since around the time when the asteroid struck Earth at the end of the Cretaceous period.

The "cataclysmic" collision filled the atmosphere with dust and debris, which blocked out the sun and prevented photosynthesis for years. The resulting mass extinction wiped out around half of all plant species on Earth at the time.

However, the researchers say the catastrophe was a "boon" for fungi. They proliferated as they consumed the plentiful dead plant material littering the ground.

Dr. Schultz said: “Extinction events can be huge disasters for most organisms, but it can actually be positive for others.

“At the end of the Cretaceous, dinosaurs did not do very well, but fungi experienced a heyday.”

He says many of the fungi that proliferated during that period likely feasted on decaying leaf litter, which brought them in close contact with ants.

Dr. Schultz explained that the insects harnessed the plentiful fungi for food and continued to rely on the hardy fungi as life rebounded from the extinction event.

The new study also revealed that it took nearly another 40 million years for ants to then develop higher agriculture.

The research team was able to trace the origin of the practice back to around 27 million years ago.

Dr. Schultz says, at that time, a rapidly cooling climate transformed environments around the globe.

In South America, drier habitats such as woody savannas and grasslands fractured large swaths of wet, tropical forests.

Dr. Schultz says that when ants took fungi out of the wet forests and into drier areas, they isolated the fungi from their wild ancestral populations.

The isolated fungi became completely reliant on ants to survive in the arid conditions, setting the course for the higher agriculture system practiced by leafcutter ants today.

Dr. Schultz added: “The ants domesticated these fungi in the same way that humans domesticated crops.

“What’s extraordinary is now we can date when the higher ants originally cultivated the higher fungi.”