Numerosity is Genetically Hardwired.

A recent study published in Science discusses evidence that our numerosity, or ability to make distinctions between numbers is genetically hardwired, rather than culturally derived1. ChickThe study presents evidence that numbers are represented on a horizontal line in space, with numbers of lesser weight to the left, and greater weight to the right, in 3 day old chicks. While this ability has been recognized in humans, it has been questioned whether this ability is innate, or culturally derived. The study offers an elegantly simple demonstration of the innate nature of this ability, which with further research may be found to originate in the common ancestor of birds and mammals.

Quote from review of paper in Science:

“The work casts doubt on the importance of language and symbolic thought for the ability to represent discrete quantities larger than 3 and to develop a sense of numerical order and counting routines. Field studies of avian behavior have previously documented this ability in adult birds. A particularly revealing model system is that of brood parasites such as cowbirds. Females of this species must locate, observe, and remember the exact location of host nests (4). They must also synchronize their own egg laying with that of the host by keeping track of the daily increase in host clutch sizes (5). The cowbirds’ reproductive success thus depends on their ability to accurately judge magnitudes in space, time, and number. Whereas the observations in cowbirds involved adult individuals, Rugani et al.‘s experiments with 3-day-old domestic chicks support the view that a general magnitude system may be functional at birth. Recent experiments with newborn humans are compatible with this notion; de Hevia et al. have shown that infants aged 8 hours to 3 days systematically related increases in numerical magnitude with increases in spatial extent and temporal duration.”

I find this research to be of particular interest because of the association of the Asymmetrical Tonic Neck Reflex (ATNR) with math skills. If numerosity extends from language and symbolic thought this linkage to ATNR does not make sense, however if numerosity is genetically derived a strong association to our capacity to move about and process information in the horizontal plane, which is associated with ATNR, is easy to accept.

Number-space mapping in the newborn chick resembles humans’ mental number line

Science 30 January 2015: 534536.


1 A very interesting discussion of how numerosity may actually be archetypal – embedded at the deepest layers of our psyche can be found here:

Jungian Archetypes: Jung, Gödel, and the History of Archetypes, Robin Robertson

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