Ancient Farmers: Ants Began Cultivating Fungi 66 Million Years Ago, Long Before Humans Discovered Agriculture

A recent study reveals that ants began practicing agriculture millions of years before humans evolved. While our ancestors-initiated farming relatively recently, ants began cultivating fungi as food roughly 66 million years ago. This groundbreaking finding highlights a long-standing agricultural partnership between ants and fungi that developed in the aftermath of a mass extinction caused by an asteroid impact at the end of the Cretaceous period. This extinction event, which eliminated half of Earth’s plant species, created favorable conditions for fungi, which thrived by decomposing the dead plant material left in the asteroid’s wake.

Research conducted by scientists at the Smithsonian’s National Museum of Natural History analyzed genetic data from hundreds of ant and fungal species. Led by entomologist Ted Schultz, this study, published in Science, traced the evolutionary timeline of ant agriculture, suggesting ants started farming fungi soon after the asteroid impact.

Over millions of years, ants and fungi co-evolved, forming a symbiotic relationship that transformed both organisms' evolutionary paths. Today, around 250 species of ants in the Americas and Caribbean continue this ancient practice, farming fungi to support their colonies.

The researchers categorized fungus-farming ants into four agricultural systems based on their methods, with leafcutter ants exhibiting the most advanced, known as higher agriculture. These ants cut fresh leaves and other plant matter, using it to cultivate fungi that provide sustenance for the colony. This agricultural practice fuels enormous colonies, sometimes numbering millions. Schultz, who has spent over three decades studying ant-fungal relationships, noted that humans might benefit from examining this successful, resilient agricultural model that has persisted for tens of millions of years.

The research team leveraged a vast collection of samples gathered from more than 30 expeditions across Central and South America. These samples allowed scientists to sequence genetic data from 475 fungal and 276 ant species, making this the most extensive dataset on fungus-farming ants ever assembled. By analyzing these samples, researchers mapped evolutionary trees for both ants and fungi, identifying the point at which ants began cultivating fungi as food. They found that fungi and ants likely began their agricultural partnership shortly after the asteroid collision that ended the Cretaceous period. The destruction and subsequent fungal proliferation led ants to rely on these organisms as a steady food source during challenging post-extinction conditions.

An intriguing outcome of the study is that it took ants another 40 million years to develop higher agriculture, a practice that became essential as the climate cooled and tropical forests began to fragment. This shift led ants to transplant fungi from moist forests into drier regions, isolating them from wild populations and fostering a dependency on ants. These fungi gradually became domesticated, much like human-cultivated crops, a process that began around 27 million years ago and persists in species like leafcutter ants.

Supported by numerous institutions, including the Smithsonian and the U.S. National Science Foundation, this research underscores how ants have long employed sophisticated agricultural techniques. These findings not only illuminate ancient ant-fungal dynamics but also open avenues for understanding resilience in agriculture.

(Source: Smithsonian’s National Museum of Natural History)