Figure 1. Relationship between normalized metabolic rate and body mass for unitary organisms and whole colonies (from Hou et al 2010)

The notion that insect colonies and their constituent individuals are analogous to multicellular organisms and their constituent cells has been a controversial idea for decades. Is it useful, for example, to think of an ant colony as a single individual? Do superorganisms really exist as coherent entities? Or do insect colonies function more as aggregations of individuals?

Last week, PNAS published the first application of empirical methods to test the superorganism concept. This is a significant paper. The researchers, led by Chen Hou, asked whether the set of relationships between mass, energy, and reproduction that govern multicellular organisms show the same patterns when measured across whole insect colonies.

The answer, in most cases, was a resounding Yes: social insect colonies grow and breathe just like regular organisms.

source: Hou, C., Kaspari, M., Vander Zanden, H. B., Gillooly, J. F. 2010. Energetic basic of colonial living in social insects. PNAS early edition.