In our recent Philosophy Phriday interview with UNC philosopher Ram Neta, Dr. Neta expressed surprise at the fact that ants have brains. But ants do indeed have brains, as certain fungi know very well, and in a study recently accepted in Developmental Neurobiology, Dr. J. Frances Kamhi and colleagues set out to understand how ant brains may develop differently in a socially simple species versus a more socially complex species.

Oecophylla

Developmental stages of Oecophylla smaragdina. Photo: Alex Wild

The researchers hypothesized that a socially simple species, Formica subserica, would exhibit more “neuroplasticity” (flexibility in brain development) than a more socially complex species, Oecophylla smaragdina, which has behaviorally and morphologically distinct worker castes. Dr. Kamhi and colleagues expected that O. smaragdina would have more rigidly determined brain structure due to the maintenance of task specialization in workers that seem less behaviorally flexible than more generalized F. subserica workers. So, they looked at ant brains! In particular, they compared the volume of brain regions that have different functions, and assessed the impact of visual experiences on regions associated with “higher-order sensory integration”.

Do you think the researchers confirmed their hypothesis? If you do, you are wrong! Surprisingly, neither species exhibited differences in brain changes due to visual experiences, and O. smaragdina – not F. subserica – exhibited greater levels of neuroplasticity as workers aged. These results suggest that social complexity, despite associated task specialization, may drive increases in neuroplasticity. It is possible that this increase is necessary to maintain higher levels of coordination and communication seen in complex ant colonies.

In conclusion, ant brains are full of surprises.