The asteroid that wiped out the dinosaurs 66 million years ago may have had an unexpected silver lining – it paved the way for the origin of ‘ant agriculture’. Asteroid impacts created a low-light environment that allowed fungi to thrive, leading an ancestor of modern leafcutter ants to start cultivating these microorganisms as a food source. This remarkable adaptation predates human agriculture by tens of millions of years.
The Fortuitous Rise of Fungus Farming
The end of the dinosaurs caused by a devastating asteroid impact turned out to have one good side effect. Post-crash low-light conditions were an ideal breeding ground for organic matter-consuming fungal life.
This choice created the window of time for a precursor of what would become leafcutter ants to evolve and begin farming those microbes. The researchers compared the genomes of 475 different fungal species which showed that the two separate lineages of fungi — both of which were later domesticated by ants — emerged sometime around 66 million years ago, shortly after the asteroid wiped out dinosaurs.
How Ants Became Fungiculturists Par Excellence
The remarkable ‘ant agriculture’ has long been a source of fascination for biologists. This mutualism, centered on the relationship between fungi and ants, is arguably a precursor of agriculture as practiced by humans but evolved over tens of millions of years ago.
The researchers found that more ‘coral fungi’, a second group of fungi, started being farmed by ants approximately 21 million years ago. It turns out, the researchers argue, these fungi had ‘pre-adapted’ before their domestication, meaning that the ants and the fungi were no strangers to one another even before an asteroid laid waste to other competitors.
The Transformation Of Ants Into Agricultural Masterminds
This probably transformed the casual relationship between ants and fungi into an ‘ obligate mutualism’ in which insects and microorganisms needed each other to survive.
Now the ants in four independent groups grow 4 different types of fungus and even shape how that fungus grows to produce some nutrients. When we grow them in the lab, they exhibit hyphal morphology as expected. However, one of these types of hyphae swells and forms grapes — clusters that are enriched with sugars (reminiscent the grape-like branches) inside the colony. ‘How the ants accomplish this is something we do not yet understand,’ says researcher Pepijn Wilhelmus Kooij.
In an extraordinary development these symbiotic relationships have led to a significant biotech interest as the enzymes manufactured by ants (depending on species) fungi can be used in the degradation of organic material and even plastic.
