If every human on Earth vanished overnight, the planet would not hand its reins to chimpanzees, dolphins, or any other brainy mammal. A growing body of peer-reviewed research points instead to a far less glamorous successor: insects, and ants in particular, already command the numerical and ecological advantage needed to fill the void. The answer challenges popular assumptions about intelligence as the key to dominance and forces a harder look at what “taking over” actually means in biological terms.
Why Humans Dominate More Than We Think
Human supremacy on Earth is not just cultural or technological. It is measurable in raw biological mass. Total biomass across all life on the planet is approximately 550 gigatons of carbon, with plants accounting for roughly 450 Gt C and all animals together making up only about 2 Gt C of carbon, most of it marine. Within that slim animal share, human biomass is an order of magnitude higher than all wild mammals combined, a ratio that reveals just how thoroughly one species has reshaped the biological balance sheet. Even without counting crops and livestock, the sheer number and body mass of people tilt global energy flows toward feeding, housing, and transporting one primate.
That dominance extends beyond sheer weight. A study in Nature Ecology and Evolution found that human-driven biomass movement now surpasses the combined movement of all terrestrial wildlife, with documented changes stretching back to 1850. Industrial fishing and whaling have simultaneously reduced marine biomass movement, meaning humans have not only grown their own footprint but actively shrunk the footprint of other large animals. The brain of Homo sapiens, which is much bigger relative to body size than that of most species, enabled abstract thinking and tool use that no competitor can match. Paired with exceptional hand dexterity and the ability to exploit a large variety of environments across every continent, humans locked in an ecological grip that no single mammal species could quickly replicate if we disappeared.
Ants Already Outweigh Wild Birds and Mammals
The strongest candidate for post-human dominance is not a primate or a predator. It is the ant. A global synthesis drawing on 489 studies estimated ant abundance at approximately 20 quadrillion individuals, with a total biomass of roughly 12 megatons of carbon. That figure already exceeds the combined biomass of wild birds and mammals and represents roughly one-fifth of human biomass. No vertebrate group outside of livestock comes close to matching that scale, and ant numbers are likely underestimates because many tropical and soil-dwelling species remain poorly surveyed.
Ants thrive on every continent except Antarctica, filling roles as predators, scavengers, seed dispersers, and soil engineers while reproducing at rates that dwarf those of any mammal. A review of nonhuman cognitive abilities noted the long-standing conjecture that insects will be left to roam the Earth long after humans are gone and that when adaptability is weighted heavily, insects rise to the top of the list of potential long-term survivors. Their colonies already function as decentralized superorganisms, coordinating labor, warfare, and even rudimentary agriculture without any centralized brain. Remove the one species that currently suppresses and reshapes ecosystems at a planetary scale, and insects face fewer constraints, not more, allowing their numbers and ecological influence to expand into abandoned farms, cities, and infrastructure.
Why Smart Mammals Would Not Fill the Gap
Popular imagination favors chimpanzees as humanity’s natural heirs. They share roughly 98% of our DNA, use tools, and possess metacognitive abilities, the capacity to think about their own thinking. Scientists have also recognized complex social structures in many animals that mirror human patterns, with hierarchies that shape health and reproduction in ways reminiscent of human societies. Yet intelligence alone does not translate into ecological dominance. Chimpanzees occupy a narrow band of tropical forest habitat, reproduce slowly, and number in the hundreds of thousands rather than the quadrillions. Their geographic range is a fraction of what modern humans exploit, and they lack the technological buffer (fire, clothing, long-distance transport) that lets people thrive from Arctic tundra to deserts.
The deeper problem is time. Modeling published in the Proceedings of the National Academy of Sciences projected that global mammal phylogenetic diversity would take millions of years to recover even if extinction rates fell back to natural background levels. Humans have already driven megafauna losses over roughly 50,000 years, gutting the large-bodied species that once anchored terrestrial food webs and leaving fewer lineages from which new giants can evolve. A recent review of late-Quaternary extinctions argued that any post-human ecosystems would be constrained by this legacy of missing megafauna and disrupted trophic networks. The ecological stage, in other words, has already been stripped of many of its leading actors. No surviving mammal can quickly evolve into those empty roles, and even highly intelligent species such as dolphins or elephants remain tied to specific habitats and slow life histories that limit explosive expansion.
What the Dinosaur Precedent Tells Us
History offers a useful parallel. After the non-avian dinosaurs went extinct 66 million years ago, mammals did not immediately surge into every open niche. Fossil evidence shows that it took millions of years for large mammalian predators and herbivores to evolve, and the path they followed was anything but predetermined. Chance, geography, and preexisting diversity all shaped which lineages radiated into dominance. The asteroid impact cleared ecological space, but the eventual winners were not the “smartest” reptiles; they were the clades best positioned to reproduce quickly, exploit new food sources, and tolerate unstable climates. Intelligence, insofar as it existed, was secondary to traits like fecundity and metabolic flexibility.
A human disappearance would create a similarly abrupt vacuum, but the starting conditions are very different from the end-Cretaceous world. Today’s ecosystems are already heavily filtered by human hunting, land use, and climate change, with many slow-breeding vertebrates pushed to the brink. Insects, by contrast, are abundant, genetically diverse, and already woven into nearly every terrestrial food web. Databases compiled through platforms such as the National Center for Biotechnology Information underscore how deeply insect genomes have diversified across extreme environments, from deserts to high mountains. In a post-human world, that latent diversity would matter more than individual cleverness, allowing insects, especially ants, to radiate into newly available niches far faster than any mammal, bird, or reptile could adapt or speciate.
Rethinking What It Means to “Take Over”
Imagining a successor to humanity often reflects human biases. We equate dominance with skyscrapers, language, and space travel, so we look for heirs among animals that seem most like us. But in ecological terms, “taking over” means controlling energy flows, shaping nutrient cycles, and influencing which other species live or die. By those metrics, ants are already powerful engineers. They aerate soils, redistribute seeds, harvest honeydew from sap-sucking insects, and wage chemical warfare on competitors. Remove human agriculture and pesticides, and many ant species would likely expand into abandoned croplands and urban spaces, accelerating their influence on plant communities and soil chemistry.
None of this implies a future ruled by ant empires in a science-fiction sense. Instead, it points to a quieter, more pervasive form of dominance: trillions of small bodies collectively steering how carbon, nitrogen, and water move through ecosystems. The same research that highlights human exceptionalism in biomass and movement also shows how contingent that dominance is on technology and social cooperation. If those vanish, the traits that matter most are not language or self-awareness but numbers, resilience, and reproductive speed. On those counts, insects, and ants in particular, are poised not just to survive a human exit, but to inherit much of the ecological influence we now wield.
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*This article was researched with the help of AI, with human editors creating the final content.
