There are studies indicating that some non-human primates, like chimpanzees and rhesus monkeys have some ordinal numerical competence.
Teratogens such as stress[1] can alter prenatal neural development, leading to diminished competence after birth.
Most research confirms that infants do in fact have a profound innate sense of number, both in abstract and finite ways.
[5] Researchers believe that this is because children around this age begin to rely heavily on the physical properties of the world and objects within it,[5] such that longer equals more.
[6] Various researchers suggest that the processing of approximate arithmetic could be related to the numerical abilities that have been independently established in various animal species[11][12][13][14] and in preverbal human infants.
[16] The combination of this potential evolutionary trait and language-based exact arithmetic may be the reason that humans are able to do advanced mathematics like physics.
Weber’s Law describes discriminability between values based on perceptual continua such as line length, brightness, and weight.
[18] Studies of rhesus monkeys' foraging decisions indicate that animals spontaneously, and without training, exhibit rudimentary numerical abilities.
Monkeys' numerical discrimination capacity is imposed by the ratio of the values compared, rather than absolute set size.
The interburst interval is varied between trials so the discrimination is based on number of bursts and not time duration of the sequence.
Studies show that rats as well as pigeons learned to make different responses to both short and long durations of signals.