An Estimated 20 Quadrillion Ants Live on Earth

Researchers have come up with an astonishing new estimate for the number of ants living on Earth: 20 quadrillion. That's 20,000,000,000,000,000 ants.

In comparison, our galaxy has around 100 billion stars. For every human alive on the planet, there are roughly 2.5 million ants. 

“It's unimaginable,” ant researcher Patrick Schultheiss of the University of Würzburg in Germany tells The Washington Post’s Dino Grandoni. “We simply cannot imagine 20 quadrillion ants in one pile, for example. It just doesn't work.”

To reach their staggering conclusion, Schultheiss and a team of researchers analyzed 489 studies that surveyed ant populations around the world. These papers represented at least seven languages and various habitat types, including forests, deserts, grasslands and cities. The team published their new results Monday in Proceedings of the National Academy of Sciences. 

“We further estimate that the world's ants collectively constitute about 12 megatons of dry carbon,” co-author Mark Wong, an ecologist at the University of Western Australia, tells CNET’s Monisha Ravisetti and Jackson Ryan. “Impressively, this exceeds the biomass of all the world's wild birds and mammals combined.”

Ants play several key roles in keeping their ecosystems in balance, including aerating the soil, dispersing seeds, decomposing organic material and serving as a food source. Like humans, these insects have spread to almost every continent on Earth. 

“Ants are the dominant insects,” famed ant researcher, or myrmecologist, E.O. Wilson told Esquire’s Tom Junod in a 2008 interview. “Each one is unique in its anatomy, its social behavior, its history. No matter where I go—except possibly Antarctica or the high Arctic, and I don't go there because there are no ants there—no matter how different the human culture, no matter how different the natural environment, there are the ants.”

The new study found that these insects are unevenly distributed across the globe, with more ants dwelling in forests and arid regions and fewer living in human-made habitats. Their numbers generally peak in the tropics, underscoring the “importance of tropical regions in maintaining healthy ant populations,” write the authors in The Conversation.

While 20 quadrillion ants may sound like a mind-bogglingly high number, this estimate is probably low, per The Conversation. Most studies the team analyzed sampled ants only from the ground layer, omitting ants in trees and underground. 

But regardless, Wong tells CNET this study provides an important baseline population, which will help scientists understand how ant numbers are responding to environmental shifts, such as climate change. 

Insect numbers have recently been plummeting across the globe. A 2019 study found that 40 percent of all insect species are threatened with extinction, while a citizen science project published in May found the U.K.’s flying insects had dropped by nearly 60 percent since 2004. Climate change, the use of chemical pesticides, invasive species, habitat destruction and fragmentation might all play a role in this decline.

In future research, the team wants to study how the ant population has changed over time. Currently, it's unclear whether ant numbers are also dropping, the Post reports. 

“To be honest,” Schultheiss tells the publication, “we have no idea.”

Margaret Osborne | | READ MORE

Margaret Osborne is a freelance journalist based in the southwestern U.S. Her work has appeared in the Sag Harbor Express and has aired on WSHU Public Radio.