Life has evolved towards ever-greater size and complexity, with entities forming collectives (e.g. cells into multicellular bodies, individuals into eusocial societies, species into obligate mutualisms). Fungus-farming ants began cultivating fungi 50 million years ago and have since evolved into over 230 species common across the New World tropics. The EU-funded INSEAME (Integrating social evolution and metabolic ecology) initiative worked to uncover the mechanisms behind the major evolutionary steps in ant societies that cultivate fungi. The researchers measured how efficient in their farming these ant societies are as the number of individuals in a colony grows. INSEAME used the fungus-farming attine ants as a model to gain a better understanding of these ant societies. The researchers utilised scaling laws to calculate the energy efficiencies the ants gained since starting their fungi cultivation 50 million years ago. The team explored the resource requirements of both the ant farmers and the fungal cultivars in a series of experiments. They measured the nutritional requirements of the ant farmers and the fungal cultivars, instead of purely energy requirements. INSEAME found a great many parallels between ant farmers and human agriculture in their history. The researchers found that, like in human agriculture, ant colonies face similar efficiency constraints that are related to metabolism. They showed that species that have large colony farms increase efficiency, giving them larger fungi crops that lose increasingly less energy through metabolic respiration. Project research also showed that colonies lost productivity when the fungal cultivars' sexual reproduction was managed. This result echoed with how early human farming struggled with unspecialised, low-productivity crops. These results have demonstrated fundamental constraints in farming that stem from incomplete domestication. This work will be of interest to those studying ants, evolution and systems thinking.
Ants, evolution, fungus-farming ants, fungi, INSEAME, ant societies, agriculture