Honeybees foraging for numbers.

The capacity to process numbers can be found in many vertebrate species, which share similar behavioral and neural mechanisms for number estimation. Honeybees possess a miniature brain but exhibit remarkable cognitive abilities, including the capacity to perform numerosity judgments in a foraging context. Honeybee foragers can count up to four landmarks en route to the goal and use this information to decide where to land. They also learn to match visual images based on item number and may use absolute or relative numerosity. They can be trained to choose item arrays based on rules such as 'smaller than', in which case their performance reveals the existence of zero as a conceptual low end of a succession of positive numbers. Moreover, in symbolic-matching protocols, they learn to master visual discriminations based on subtracting or adding one item to a perceived sample, depending on the color of the sample array. Here I review the works on numeric processing in bees and discuss them from a cognitive and ecological perspective. I conclude that these abilities exhibit distinctive features of the vertebrates' numeric systems, and argue in favor of an evolutionary convergence of numeric abilities in many animal species, including vertebrates, and invertebrates.