If you’re building an army, do you prioritise the protective armour you can supply to an individual, or the numbers you can afford to recruit if the armour’s built on the cheap? For ants, this trade-off appears to have played a central role in the emergence of complex societies, according to new research by Darwin PhD Zoology student Arthur Matte.
In a paper published in Science Advances in December, Arthur explored how ants have balanced protection and numbers as they have evolved. A thick external cuticle helps protect individual ants from threats such as disease and physical damage, but is expensive to build at scale, relying on scarce nutrients such as nitrogen.
Arthur developed computer vision algorithms to analyse 3D X-ray scans of ants, measuring cuticle thickness across more than 500 species. He found a strong relationship between cuticle investment and colony size: species with thinner cuticles consistently formed larger colonies. By spending less on each worker, colonies can afford to produce many more of them, shifting the balance from individual robustness to collective strength and enabling the rise of larger, more complex groups.
“This evolutionary shift, toward cheaper yet more numerous workers, paved the way for the explosive rise of ant societies that are now found across nearly all terrestrial ecosystems,” explains Arthur.
“The trade-off between quantity and quality is all around. It’s in the food you eat, the books you read, the offspring you want to raise. It was fascinating to retrace how ants handled it through their long evolution. We could see lineages taking different directions, shaped by different constraints and environments, and ultimately giving rise to the extraordinary diversity we observe today.”
The story was covered in the New York Times.
