Is the report by Cammaerts and Caemmaerts (2015) positive evidence of self-recognition in ants? Our answer is an emphatic no. Too many crucial methodological details are not given. No formal period between marking the subjects and then exposing them to the mirror was included; the reader is simply asked to accept that no self-cleaning movements occurred before marked ants first saw themselves in the mirror and that marked ants without any mirror did not do so. There is no clear mention of how these data were collected. Were the ants recorded on video? Were they observed directly? In other studies of ant behavior some means of magnification are used, but Caemmerts and Cammaerts provide no information about this, and it is not even clear if any attempt to assess inter-observer reliability was made.
It also remains a possibility that responses to the mirror on the mark test were confounded by chemical cues from the ant’s antennae and chemoreceptors on the mandibles. For instance, if the blue dye was chemically different from the brown dye, chemoreception could explain why ants marked with blue dye were more likely to be attacked by other ants. It is also important to note that the ants must have sensed that they had the marks on themselves through these and other olfactory channels prior to being exposed to the mirror, which would invalidate the mark test.
Notwithstanding the absence of evidence for vision-based individual facial recognition in ants, it would be astonishing if such poorly sighted, small brained insects − especially those without any mirror experience − could immediately use their reflection to try to remove a freshly applied foreign mark that was only visible in the mirror
There’s some criticism here:
Hi MichaelStJules! We’ll consider that paper for a clarificatory commentary on this. Thanks again for your suggestions!