If you were to design the strangest diet possible, eating nothing but ants and termites would probably make the shortlist. Yet over the past 66 million years, mammals across the globe have repeatedly gone down this path—not once or twice, but at least a dozen times. From anteaters and aardvarks to pangolins and aardwolves, the so-called myrmecophages (animals that feed on ants and termites) have evolved similar traits: they’ve lost most or all of their teeth, grown long sticky tongues, and learned to consume insects by the tens to hundreds of thousands each day.
A new study reveals that this extreme dietary specialization, once thought rare and mysterious, has emerged independently in mammals at least 12 times in the last 66 million years (i.e., since the Cenozoic era began). This is a striking example of convergent evolution and shows just how powerful ants and termites have been in shaping mammalian history.
“The number of distinct origins for myrmecophagy was certainly surprising, as was the discovery that their origins seem to quite neatly follow the trend of growth across ant and termite colony sizes throughout the Cenozoic,” Thomas Vida, first author of the study and a researcher at the University of Bonn, told Ars Technica.
The rise of insect-eating mammals
To figure out how often and when mammals evolved a taste for ants and termites, the study authors first had to track down which species are truly “obligate myrmecophages”—animals that rely entirely on ants and termites, with little to no other food in their diet. That meant going through nearly a century’s worth of information. “We looked through a very large number of published natural history papers, zoological texts, and conservation reports as a baseline for identification,” Vida added.
This board dataset covered 4,099 living mammal species. The researchers then grouped these species into one of five dietary categories based on gut analyses and field observations: strict ant/termite specialists, general insect-eaters, carnivores, omnivores, and herbivores. Next, they ran several statistical models to work backward from this data to reconstruct the most likely diets for each ancestral node.
The results showed at least 12 separate origins of obligate myrmecophagy, with instances in each of the three main mammal groups: monotremes (egg-laying mammals), marsupials, and placentals. Surprisingly, some families, like Carnivora (dogs, bears, weasels), were responsible for about a quarter of all these origins, suggesting certain lineages were predisposed to make the leap.
Moreover, in every case, the ancestors were either insectivores or carnivores, with insect-eaters making the shift about three times more often than carnivores. The researchers also compared these timelines with the expansion of ants and termites themselves. Fossil evidence shows that during the Cretaceous (about 145–66 million years ago), these insects made up less than 1 percent of all insects on Earth.
It wasn’t until after the K–Pg extinction event, which wiped out all non-avian dinosaurs and reshaped ecosystems, that ant and termite colonies began to expand. By the Miocene epoch (~23 million years ago), they accounted for 35 percent of all insect specimens. “The increasing abundance of social insects over the last 50 million years or so led to the repeated evolution of specialized diets in mammals. We sometimes call this selective pressure,” Phillip Barden, one of the study authors and a professor of biology at New Jersey Institute of Technology, told Ars.
Once mammals switched to an ant-and-termite-only diet, they almost never went back. The elephant shrew genus Macroscelides was the sole exception, shifting to omnivory after adopting myrmecophagy during the Eocene. This suggests that such specialization can be an evolutionary one-way street, possibly because losing teeth and developing highly adapted tongues, claws, and stomachs makes it difficult to return to a generalist diet.
“We only recover a single reversal out of specialized ant- and termite-eating, which could mean a few things. One possibility is that it is exceptionally difficult to re-evolve baseline feeding features once you become heavily specialized. It could also be that betting on ants and termites tends to pay off, that is, there is little selective pressure to de-specialize given the ubiquity of social insects in many environments,” Barden explained.
Insects are more influential than we realize
By showing that ant- and termite-based diets evolved repeatedly, the study highlights the overlooked role of social insects in shaping biodiversity. “This work gives us the first real roadmap, and what really stands out is just how powerful a selective force ants and termites have been over the last 50 million years, shaping environments and literally changing the face of entire species,” Barden said.
However, according to the study authors, we still do not have a clear picture of how much of an impact insects have had on the history of life on our planet. Lots of lineages have been reshaped by organisms with outsize biomass—and today, ants and termites have a combined biomass exceeding that of all living wild mammals, giving them a massive evolutionary influence.
However, there’s also a flip side. Eight of the 12 myrmecophagous origins are represented by just a single species, meaning most of these lineages could be vulnerable if their insect food sources decline. As Barden put it, “In some ways, specializing in ants and termites paints a species into a corner. But as long as social insects dominate the world’s biomass, these mammals may have an edge, especially as climate change seems to favor species with massive colonies, like fire ants and other invasive social insects.”
For now, the study authors plan to keep exploring how ants, termites, and other social insects have shaped life over millions of years, not through controlled lab experiments, but by continuing to use nature itself as the ultimate evolutionary archive. “Finding accurate dietary information for obscure mammals can be tedious, but each piece of data adds to our understanding of how these extraordinary diets came to be,” Vida argued.
Evolution, 2025. DOI: 10.1093/evolut/qpaf121 (About DOIs)
Rupendra Brahambhatt is an experienced journalist and filmmaker. He covers science and culture news, and for the last five years, he has been actively working with some of the most innovative news agencies, magazines, and media brands operating in different parts of the globe.
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