The study finds ants succeed globally by reducing per-worker investment in nutritionally costly cuticle tissue and relying on large colonies. Researchers analyzed 3D X-ray scans of more than 500 ant species and found body-mass-to-cuticle ratios ranging from ~6% to ~35%, with thinner cuticles linked to larger colonies. Lower cuticle investment may also promote diversification and allow expansion into nutrient-poor habitats, illustrating a broader trade-off between individual robustness and collective success.
How ‘Weak’ Ants Won the World: The Evolutionary Power of Numbers
A 3D reconstruction of the exoskeleton of an ant worker (Myrmoteras sp.) from x-ray tomography.
Here’s a striking (and slightly unsettling) statistic: the planet supports roughly 20 quadrillion ants — about 20,000,000,000,000,000 six-legged insects. A team of entomologists argues that one key to their global success is an evolutionary trade-off: ants invest less in costly individual body armor and instead rely on sheer numbers and collective organization.
The research, published in Science Advances, explores how investment in the cuticle — the hardened outer layer that forms an ant’s exoskeleton — shapes colony size, diversification, and ecological reach. The cuticle protects ants from predators, pathogens and drying out, and also serves as mechanical support for muscles. But it is nutritionally expensive to build and maintain, demanding scarce elements such as nitrogen and various minerals.
From this perspective, a thicker cuticle raises the per-worker nutritional cost and can limit how large a colony can grow. The authors hypothesized that species which reduced per-worker cuticle investment could support larger worker populations and, in turn, gain collective benefits.
What the Researchers Did
Using >500 ant species, the team analyzed 3D X-ray scans to measure the ratio of cuticle volume to total body volume. They found wide variation: body-mass-to-cuticle proportions ranged from roughly 6% up to about 35%. Feeding these measurements into evolutionary models, the researchers detected a clear pattern: species with relatively less cuticle per worker tend to form larger colonies.
“Ants are everywhere. Yet the fundamental biological strategies which enabled their massive colonies and extraordinary diversification remain unclear,”
— Arthur Matte, University of Cambridge (study co-author)
“For example, the individuals may themselves become simpler because tasks that a solitary organism would need to complete can be handled by a collective.”
— Evan Economo, University of Maryland (study co-author)
Why It Matters
The study suggests a repeatable evolutionary strategy: by reducing investment in one of the most nutritionally expensive tissues, ants shift resources from costly individual robustness toward a distributed, many-worker system. That shift appears linked not only to larger colonies but also to higher diversification rates — a common measure of evolutionary success.
The authors propose a possible mechanism: lower cuticle demands less nitrogen and scarce minerals, enabling some ant lineages to invade nutrient-poor habitats and diversify. Over generations, this quantity-versus-quality trade-off may have created an evolutionary feedback loop: more numerous, individually vulnerable workers but stronger collective resilience in disease control, nest defense and resource exploitation.
Matte draws an analogy to the evolution of multicellularity: cooperating units may be individually simpler, yet their integration produces a far more complex, successful organism. The study highlights a general biological tension between individual investment and collective payoff — a principle that resonates beyond ants.
Key takeaway: Ants’ global dominance may stem less from individual toughness and more from optimized resource allocation that favors large, cooperative societies over single, well-armored workers.
