Number sense in animals
Number sense in animals is the ability of creatures to represent and discriminate quantities of relative sizes by number sense. It has been observed in various species, from fish to primates. Animals are believed to have an approximate number system, the same system for number representation demonstrated by humans, which is more precise for smaller quantities and less so for larger values. An exact representation of numbers higher than three has not been attested in wild animals, but can be demonstrated after a period of training in captive animals. In order to distinguish number sense in animals from the symbolic and verbal number system in humans, researchers use the term numerosity, rather than number, to refer to the concept that supports approximate estimation but does not support an exact representation of number quality. Number sense in animals includes the recognition and comparison of number quantities. Some numerical operations, such as addition, have been demonstrated in many species, including rats and great apes. Representing fractions and fraction addition has been observed in chimpanzees. A wide range of species with an approximate number system suggests an early evolutionary origin of this mechanism or multiple convergent evolution events. Like humans, chicks have a left-to-right mental number line (they associate the left space with smaller numbers and the right space with larger numbers). (Wikipedia).
