Study suggests that the practice emerged after the extinction of the dinosaurs, driven by the abundance of fungi and the scarcity of plants; complete domestication of the species would have occurred around 27 million years ago
A study on the evolution of ants suggests details about the emergence of agriculture among these insects. Scientists have discovered that the relationship between ants and fungi began about 66 million years ago. It coincided with the impact of the asteroid that wiped out the dinosaurs. The temporary interruption of photosynthesis caused by the event favored the growth of fungi. They became a food source for the ants. Thus began a partnership that evolved over millions of years.
The researchers plotted evolutionary trees for 475 species of fungi and 276 species of ants. These trees allowed them to identify key moments in the coevolution of these organisms. They revealed that agriculture practiced by ants may have emerged independently at least twice after the extinction of the dinosaurs.
Initially, ants cultivated fungi that also existed freely in nature. However, around 27 million years ago, some species began to completely domesticate their fungi, making them dependent on them.
This domestication coincided with a period of global climate change, which transformed the humid forests of South America into drier regions with large areas of grassland. Adapting to the new environment, the ants continued to cultivate the fungi. This resulted in the separation of wild fungal populations and the emergence of domesticated lineages, such as Leucoagaricus gongylophorus (cultivated by leaf-cutter ants). These ants began to play a crucial role in maintaining the fungi, which had lost their ability to live independently.
The research, published in the journal Science (doi.org/10.1126/science.adn7179), was conducted by a team that used more than 30 years of field samples and fossils to calibrate evolutionary trees. Their findings indicate the complexity of the relationship between ants and fungi. And they suggest that agriculture, both among humans and among ants, may emerge in response to major environmental changes.
However, scientists cannot say for sure that the asteroid impact was the trigger for this mutuality. But their data show a significant correlation between the events.