Earth has 20 quadrillion ants, says new population study

Earth has 20 quadrillion ants, says new population study

Earth has 20 quadrillion ants, says new population study

It’s the world of the ants, and we’re just visiting.

A new estimate of the total number of ants burrowing and buzzing on Earth comes to a whopping total of nearly 20 quadrillion individuals.

The staggering sum – 20,000,000,000,000,000 or 20,000 trillion – reveals the ants’ astonishing ubiquity even as scientists worry that a possible mass die-off of insects could destroy ecosystems.

In a paper published Monday by the Proceedings of the National Academy of Sciences, a group of researchers from the University of Hong Kong analyzed 489 studies and concluded that the total mass of ants on Earth weighs in at about 12 megatons of dry carbon.

Put another way: if all the ants were picked off the ground and put on a scale, they would outweigh all the wild birds and mammals combined. For each person, there are approximately 2.5 million ants.

“It’s unthinkable,” said Patrick Schultheiss, a lead author on the study who is now a researcher at the University of Würzburg in Germany, in a Zoom interview. “We simply cannot imagine 20 quadrillion ants in one pile, for example. It just doesn’t work.”

Counting all of these insects — or at least enough of them to come up with a good estimate — involved combining data from “thousands of authors in many different countries” over the course of a century, Schultheiss added.

To measure insects that outnumber ants, there are two ways to do it: Get down on the ground to sample leaf litter – or set small traps (often just a plastic cup) and wait for the ants to slide in. Scientists have gotten their boots dirty with surveys in almost every corner of the world, although some places in Africa and Asia lack data.

“There is a truly global effort that goes into these numbers,” Schultheiss said.

Ants, like humans, have marched across virtually every continent and every kind of habitat. Ground-dwelling ants are most abundant in tropical and subtropical regions, according to the research team, but they can be found almost everywhere except the coldest parts of the planet.

Or as the renowned author and myrmecologist (meaning antologist) EO Wilson once put it: “Wherever 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 is, it’s the ants.”

The world might actually be better off with all these ants. By tunneling, they aerate the soil and pull seeds underground to germinate. They serve as a source of food for countless arthropods, birds and mammals. While carpenter ants are annoying to homeowners, forests would be stacked to the brim with dead wood without the decomposing power of wood-destroying insects.

Entomologists are seeing alarming declines in insect populations beyond ants in Germany, Puerto Rico and elsewhere. Habitat destruction, pesticides and climate change contribute to this potential, but still debatedbugpocalypse.” Over 40 percent of insect species could become extinct, according to a 2019 study, with butterflies and beetles facing the greatest threat.

Scientists are not sure if the number of ants is also falling. “To be honest,” Schultheiss said, “we have no idea.”

That is the next research question the team wants to answer. “We have not yet attempted to show this temporal shift in ant abundance,” Sabine Nooten, an insect ecologist and co-author of the study, told Zoom. “It would be something that would move forward.”

For decades, researchers have peered into ant farms in laboratories to test theories about animal behavior. Antologist Wilson, who died last year, used his insights into ants to explain the genetic basis of animal cooperation and to emphasize the sheer biodiversity of life worth preserving.

In the 1990s, he ventured a rough guess at the earth’s ant population together with fellow biologist Bert Hölldobler. Their estimate was about 10 quadrillion — within the same order of magnitude as the recent, more stringent estimate published Monday.

“In the case of EO Wilson, he was simply a very smart man,” Schultheiss said. “He knew an incredible amount about ants and had a gut feeling, basically.”

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