fruit flies (‘drosophila melanogaster’) can discriminate between sets containing different numbers of objects and spontaneously show a preference for larger numbers. This numerical judgment requires the activation of specific neurons located in the optic lobe, which also intervene in a social context, allowing the fly to adapt its behavior in response to a threat.
The ability to “count” friends and enemies may have played a role in the evolution of these insects, researchers explain in a new study published in the journal Cell Reports.
Estimate the number of conspecifics in a competing group before conflict, the amount of food available in a place that is difficult to access, or the number of possible sexual partners in a new territory is essential for survival and reproduction. For example, some species of ants orient themselves in the desert by calculating the number of steps required to reach a goal.
“Numerical sensitivity, that is, the ability to perceive information related to quantities, exists in many vertebrates and invertebrates. It has been documented in primates, birds, amphibians, fish, and bees,” explains Mercedes Bengochea, a postdoctoral researcher in Bassem Hassan’s team. at the Brain Institute in Paris (France)–, but we didn’t know which neural circuits were involved in this ability.”
To investigate this question, researchers must recording the brain activity of an animal during a numerical task and then turning specific neural cells on or off to determine which areas of the brain are involved. These operations are difficult to perform in vertebrates, but the right tools already exist with fruit flies.