Have you ever stopped to wonder about the tiny creatures marching beneath your feet? Ants, often seen as a nuisance at picnics, are actually vital components of our planet’s ecosystems. A groundbreaking new study has delved into the global population of these insects, revealing a number that is truly astonishing: 20 quadrillion ants inhabit the Earth. That’s twenty followed by fifteen zeros, or approximately 2.5 million ants for every single person alive today.
This mind-boggling estimate, published in the Proceedings of the National Academy of Sciences (PNAS), comes from biologists who meticulously analyzed hundreds of existing studies on ant populations from around the world. This comprehensive research provides us with an unprecedented understanding of the sheer scale of ant life on our planet and highlights their crucial role in maintaining ecological balance.
The researchers themselves emphasize that even this immense figure of 20 quadrillion ants is likely an underestimate. Their analysis couldn’t fully account for ant colonies thriving underground, and they lacked sufficient data from vast regions like Northern Asia and Central Africa. Despite these limitations, the study’s findings have sparked a renewed appreciation for these ubiquitous insects, even among the scientists who conducted the research.
“I think we quickly overlook what’s beneath our feet,” notes Sabine Nooten, an insect ecologist at the University of Würzburg in Germany and co-lead author of the study. Working with co-lead author Patrick Schultheiss, also an ecologist, Nooten conducted this research during their time at the University of Hong Kong. Their work underscores the importance of recognizing and understanding the often-unseen world of insects that plays such a critical role in our environment.
Ants are undeniably one of the most successful groups of organisms on Earth. Having evolved over 140 million years ago, they have become integral to almost every terrestrial ecosystem. Their success is largely attributed to their complex social structures. Ant colonies function with remarkable efficiency and instinct, performing essential tasks that benefit the environment in countless ways. They are natural soil aerators, improving soil health by tunneling and creating pathways for air and water. They act as seed dispersers, carrying seeds underground which aids in plant propagation and forest regeneration. Furthermore, ants are a fundamental food source for a vast array of other creatures, forming a vital link in the food chain.
The study further highlights the immense biomass of the world’s ant population. Collectively, ants weigh an estimated 12 metric megatons of dry carbon. To put this into perspective, this biomass surpasses the combined weight of all wild birds and mammals on Earth. It’s twice the weight of the Great Pyramid of Khufu, an iconic ancient monument, and over one-fifth the weight of the monumental Great Wall of China. This staggering biomass underscores the profound impact ants have on our planet’s ecology and nutrient cycles.
The research team discovered that ant distribution is far from uniform across the globe. They are particularly abundant in tropical forested regions, where warm, humid conditions support thriving colonies. Arid shrublands are also hotspots of ant activity, showcasing their adaptability to diverse environments. With over 12,000 known species, ants exhibit an incredible array of adaptations. Consider carpenter ants, renowned for their powerful mandibles that they use to excavate wood for nest building, playing a crucial role in wood decomposition and nutrient cycling. Fire ants, despite their small size, are known for their aggressive nature and painful venom, impacting local ecosystems and agriculture. Leafcutter ants demonstrate a remarkable symbiotic relationship with fungi, cultivating underground fungal gardens using harvested leaves as fertilizer, contributing to nutrient cycling and plant diversity in neotropical forests.
To conduct their global assessment, the scientists began by compiling an extensive database, initially curated by senior author Benoit Guénard from the University of Hong Kong. This index contained nearly 9,000 ant studies spanning eight decades of research. Expanding beyond this initial collection, they scoured the internet for any relevant studies conducted across all continents and major biomes. After rigorous analysis, the team narrowed down their dataset to 489 studies. This careful selection process was necessary because many studies lacked quantitative data on ant abundance or employed inconsistent collection methodologies, ensuring the robustness and reliability of their final estimate.
Sabine Nooten explains that two primary methods are used for collecting ants in ecological studies: pitfall traps and leaf litter sampling. Pitfall traps are buried containers that passively capture foraging ants, providing a measure of ant activity and abundance in a given area. Leaf litter sampling involves carefully extracting and counting ants from a defined area of leaf litter and humus, offering a more comprehensive assessment of ant density within a specific habitat.
By extrapolating data from these standardized studies to comparable environments worldwide, the researchers arrived at their monumental estimate of 20 quadrillion ants. This figure is significantly higher, ranging from two to twenty times greater, than previous estimations, highlighting the advancements in our understanding of global ant populations. To visualize this number, a chain of 20 quadrillion ants would stretch around the Earth’s equator nearly 8 million times, emphasizing the sheer scale of their global presence.
Patrick Schultheiss emphasizes that their current estimate is likely to increase as research progresses. Subterranean ant populations, which are notoriously difficult to study, could potentially add another 2 to 20 quadrillion ants to the global count. Beyond just numbers, scientists are still actively investigating the multifaceted roles ants play in our complex ecosystems. “We realize they’re important, we just don’t know how important,” Schultheiss concludes, stressing the ongoing need for further research to fully understand the ecological significance of ants.
Other scientists have recognized the significance of this extensive analysis and its potential to engage the wider public. Nate Sanders, an ecologist at the University of Michigan, who was not involved in the study, believes it will inspire further exploration and discovery. “I think any study that clearly points out where gaps in knowledge are should inspire students, scientists, and folks who love ants to head out into the woods to see what’s there,” he stated.
Benoit Guénard highlights the accessibility of ant research, encouraging citizen science participation. “Counting ants is not a difficult exercise,” Guénard stated. “Citizens from all over the world, with the right methodology, could be involved in providing a more profound understanding of the changes that are happening over time and space.” This call for broader participation underscores the potential for collaborative efforts to deepen our understanding of these tiny yet incredibly important creatures and their response to global environmental changes.
Citation:
Schultheiss, P., Nooten, S.S., Wang, R., Wong, M.K.L., Brassard, F., Guénard, B. (2022). The abundance, biomass, and distribution of ants on Earth. Proceedings of the National Academy of Sciences, 119 (40) e2201550119. https://doi.org/10.1073/pnas.2201550119.
