When it comes to survival, is quality or quantity better? Or, as they say in the United States: Would you rather fight a duck the size of a horse or 100 horses the size of geese? It seems like an idle question (and put that way it is a bit…), but at least for the ants it is an essential question.
A new study published in Science Advances in fact, it demonstrates that the more numerous an ant colony is, the weaker its individual individuals are.
Quantity works better. The study focused on ants but started from a broader point of view: the idea that the more complex a society becomes, the more “simple” individuals become, because they can divide roles and carry out complex tasks by joining forces – while solitary individuals have to do everything alone.
The University of Maryland team tried to test this theory on a social insect, and they chose ants because, as first author Arthur Matte, a PhD student at the University of Cambridge, said, “they’re everywhere.”
Thin armor. The researchers focused specifically on the ants’ cuticle, their “skin” that serves as a protective layer against predators, dehydration and pathogens. Producing the cuticle is expensive from a nutritional point of view, also because it requires the use of relatively low-abundance elements. The thicker a cuticle, therefore, the more expensive it was to produce: the advantage is that it is much more protective than a thin cuticle and, so to speak, cheaper.
Well: the study of the cuticles of more than 500 different species of ants has unequivocally demonstrated that the more numerous the colonies, the thinner the armor of the individual individuals.
Exclusive to ants? The reason is easily explained: by saving on their own armor, individual ants have more energy available to dedicate to the colony, which the more numerous it is, the more expensive it is to maintain. The most solitary ants, which live in colonies of a few hundred if not dozens of specimens, have a cuticle that “covers” 35% of their energy investment; the most numerous species see this number drop to 6%.
Social insects. The link between thinner cuticles and more numerous colonies has created, in many ant species, a positive loop: the more numerous a colony is, the less it needs heavily armed individuals, the more resources it has available to further increase in number and also colonize new environments.
The authors of the study hypothesize, and will soon test the hypothesis, that similar evolutionary paths are found in other social organisms, for example termites.
