Ants Acquire the Notion of Zero through Experiences

The workers of the ant Myrmica sabuleti have a concrete notion of zero and locate this zero at the lower end of their mental number line. Here we examined how they acquire such a notion: do they have it natively or do they learn it over their life? We worked on young ants a few weeks old, and used operant conditioning to zero, the latter being a white paper or ‘nothing, no cue’, presented vs a black dot. In a first series of experiments, we showed that young ants do not detain the notion of zero. In a second series of experiments on the same ants, we first tempted learning them the notion of zero by facing them with a filled and an empty food tube during two days. They were then submitted to conditioning to ‘zero’, and they correctly responded to it. Consequently, the ants have not natively the notion of zero but acquire it through experiences.