The team was amazed to observe that although the bees often picked incorrectly, they chose the empty card over cards with varying numbers of symbols more frequently than would be predicted by random chance; implying that they could, at least partially, grasp the idea that the absence of something is the lowest possible quantity.
It may sound simple to an adult human, but such reasoning represents a huge mental leap because the animal brain arose to process and respond to the environment around it – a world filled with tangible threats and resources that presents no inherent representation for nothingness.
"This is a tricky neuroscience problem," Dyer said. "It is relatively easy for neurons to respond to stimuli such as light or the presence of an object but how do we, or even an insect, understand what nothing is?"
In order to confirm the surprising findings, a collaborator from France repeated the study design. Her group achieved the same results.
Given the huge gaps on the evolutionary tree that lie between the handful of animals that can understand zero, the collective team concluded that the cognitive ability has arisen multiple times, independently, in response to organisms trying to survive complex environments. (After all, being able to think “there is an absence of cave lions around, therefore it’s safe for me to sleep” is quite advantageous.)
And considering the capacity seemingly requires shockingly few brain cells, they speculate that it is likely to be present in many more species.