Why evolution rewarded ants that sacrificed protection
Some ants thrive by choosing numbers over strength. Instead of heavily protecting each worker, they invest fewer resources in individual armor and produce far more ants. Larger colonies then compensate with collective behaviors like group defense and coordinated foraging. The strategy has been linked to evolutionary success and greater species diversity.
The question is playful and unrealistic, but it points to a serious idea: the tension between quantity and quality. New research suggests this same tradeoff has shaped evolution, especially in the rise of complex animal societies.
How ants choose numbers over toughness
A study published on December 19, 2025, in the journal Science Advances reports that some ant species organize their colonies by prioritizing numbers rather than individual strength. These ants invest less in each worker's cuticle -- the hard outer layer of the exoskeleton -- which frees up valuable nutrients. Those resources can then be used to produce more workers. According to the researchers, this approach of creating many less-protected ants instead of fewer heavily armored ones proved to be evolutionarily successful. The findings help explain how individuals can change as large, complex societies develop, including those seen in humans.
"There's this question in biology of what happens to individuals as societies they are in get more complex. For example, the individuals may themselves become simpler because tasks that a solitary organism would need to complete can be handled by a collective," said senior author Evan Economo, chair of the Department of Entomology at the University of Maryland.
In this context, individuals can become what scientists describe as "cheaper." That means they require fewer resources to build and can be produced in larger numbers, even if each one is less physically robust.
"That idea hasn't been explicitly tested with large-scale analyses of social insects until now," said Economo, who also holds the James B. Gahan and Margaret H. Gahan Professorship at UMD.
Why ants are ideal for studying social evolution
Ants offer an unusually good system for exploring how complex societies evolve. Depending on the species, ant colonies can range from just a few dozen members to many millions.
"Ants are everywhere," said lead author Arthur Matte, a Ph.D. student in zoology at the University of Cambridge. "Yet the fundamental biological strategies which enabled their massive colonies and extraordinary diversification remain unclear."
The research team proposed that colony size might be linked to how much ants invest in their cuticle.
The cost of building body armor
The cuticle plays several important roles. It helps protect ants from predators, drying out, and disease, and it provides structural support for their muscles. At the same time, it is expensive to produce because it requires limited nutrients such as nitrogen and various minerals. Making a thicker cuticle uses more of these resources, which could restrict how many individuals a colony can support.
To investigate this idea, the researchers analyzed a large dataset of 3D X-ray scans from more than 500 ant species. They measured both total body volume and cuticle volume, finding that investment in the cuticle varied widely, from 6% to 35% of an ant's body. When these measurements were fed into evolutionary models, a clear trend emerged: species that devoted less of their body to cuticle tended to form larger colonies.