Why mammals continue to evolve to eat ants – over and over again

According to new research, extreme appetite for ants and termites has appeared independently in at least 12 times over the past 66 million years. Scientists at New Jersey Institute of Technology tracked this specialized feeding strategy for thousands of mammals and found that the rise of social insects after dinosaurs extinction has triggered a series of evolutionary adaptations for mammals around the world.

The comprehensive study, published in Theory of Evolution, analyzed dietary data from 4,099 mammals to understand how and when this particular dietary habit was developed in different animal lineages after dramatic ecosystem changes that occurred after non-avian dinosaurs.

Extreme dietary commitments require significant changes

Today, only about 20 mammals are eligible to be true nutmeg phages, and these animals have evolved to consume only ants and termites. These experts include giant drug resistance, Aardvarks and Pangolins, all of which develop significant adaptability: slender sticky tongue, specialized claws, improved stomach, and reduced or missing teeth.

The commitment required is astonishing in terms of daily consumption. Numbat has to consume about 20,000 termites a day to meet its energy needs, while Aardwolf can spot up to 300,000 insects in one night, demonstrating the energy capabilities of these tiny prey.

“It has not been investigated yet how this dramatic diet evolved across all known mammal species,” explains Phillip Barden, the corresponding author of the study and associate professor of biology at NJIT. “This work provides us with the first real roadmap, and what really stands out is the strength of selective power ants and termites over the past 50 million years.”

After the dinosaurs became rich, social insects became rich

The team traced the evolution of ants and termite colonies to 145 million years to understand when these insects became the primary food source. During the Cretaceous period, ants and termites were less than 1% of Earth’s insects, and were too rare to support professional feeders.

Things have changed dramatically after the K-PG extinction event of non-Avian dinosaurs were eliminated. Ants and termites expanded rapidly in the reorganized ecosystem, reaching modern abundance levels approximately 23 million years ago, when they accounted for 35% of all insect specimens.

Key evolutionary patterns found:

• Each major mammal group evolved once nutmeg type: single, marsupial and placenta
• All professional ant-man comes from insect or carnivorous ancestors
• Insect species make the transition frequency three times higher than that of carnivores
• There is only one known reversal: elephant sh is transformed into omnivorous
• Eight of the twelve evolutionary origins are represented by a single species today

Carnivore families show surprising adaptability

An unexpected discovery appeared in the Carnivora family, including dogs, bears and weasels. Despite the huge shift from feeding vertebrates to consuming thousands of tiny insects, the group accounts for about 25% of all nutmeg origins.

“It’s a surprise. From eating other vertebrates to consuming thousands of tiny insects is a major shift,” Baden noted. “Part of susceptibility may be some physiological characteristics or dentitions that are more extended to handle social insect diets.”

Researchers gather dietary information from nearly a century of natural history, conservation reports and classification descriptions to create their comprehensive database. They divided the species into five dietary groups and mapped them to a time-screened mammalian genealogy to reconstruct the ancestral diet using statistical models.

A dead end of evolution or a competitive advantage?

The study shows that once mammals are committed to nutmeg, they rarely diversify or transfer back to a regular diet. This specialization creates evolutionary limitations—the twelve origins are represented by only a single species, indicating limited potential for diversity.

But this obvious limitation may actually represent an advantage in our ever-changing world. As climate change favors species with huge colonies, including invasive social insects, such as fire ants, professional feeders may find themselves in a good attitude to achieve future success.

“In some ways, specializing in ants and termites will paint a species into corners,” Baden observed. “But as long as social insects occupy the world’s biomass, these mammals may have an advantage, especially as climate change appears to favor species with huge colonies.”

Today, ants and termites have over 15,000 species with combined biomass over all wild mammals, making them one of the most successful groups on Earth and ensuring a sustained food supply to their professional predators.

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