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.