This blog maintains that the emergence of humans six million years ago represented a rare biological “transition” to collective function similar to “eusocial” insects, mainly ants, bees and termites. For the first time, there has been a reliable estimate of how many ants are on earth. This paper illustrates that collective function has propelled both these insects and ourselves to be the most successful creatures on our planet (for good or ill). Here is the significance and abstract from the paper from the Proceedings of the National Academy of Sciences:
The astounding ubiquity of ants has prompted many naturalists to contemplate their exact number on Earth, but systematic and empirically derived estimates are lacking. Integrating data from all continents and major biomes, we conservatively estimate 20 × 1015 (20 quadrillion) ants on Earth, with a total biomass of 12 megatons of dry carbon. This exceeds the combined biomass of wild birds and mammals and equals 20% of human biomass. Ant abundance is distributed unevenly on Earth, peaking in the tropics and varying sixfold among habitats. Our global map of ant abundance expands our understanding of the geography of ant diversity and provides a baseline for predicting ants’ responses to worrying environmental changes that currently impact insect biomass.
Knowledge on the distribution and abundance of organisms is fundamental to understanding their roles within ecosystems and their ecological importance for other taxa. Such knowledge is currently lacking for insects, which have long been regarded as the “little things that run the world”. Even for ubiquitous insects, such as ants, which are of tremendous ecological significance, there is currently neither a reliable estimate of their total number on Earth nor of their abundance in particular biomes or habitats. We compile data on ground-dwelling and arboreal ants to obtain an empirical estimate of global ant abundance. Our analysis is based on 489 studies, spanning all continents, major biomes, and habitats. We conservatively estimate total abundance of ground-dwelling ants at over 3 × 1015 and estimate the number of all ants on Earth to be almost 20 × 1015 individuals. The latter corresponds to a biomass of ∼12 megatons of dry carbon. This exceeds the combined biomass of wild birds and mammals and is equivalent to ∼20% of human biomass. Abundances of ground-dwelling ants are strongly concentrated in tropical and subtropical regions but vary substantially across habitats. The density of leaf-litter ants is highest in forests, while the numbers of actively ground-foraging ants are highest in arid regions. This study highlights the central role ants play in terrestrial ecosystems but also major ecological and geographic gaps in our current knowledge. Our results provide a crucial baseline for exploring environmental drivers of ant-abundance patterns and for tracking the responses of insects to environmental change.