Yes, babies do have a number sense

references

These last two decades, cognitive Neuroscience and scientific Psychology have provided insights on the cognitive development of children and babies.

Before the advent of Cognitive sciences, Piaget’s views were predominant in Development Psychology, assuming that numerical skills started to appear later in childhood.

Things are not that simple and straight. At birth, the mammalian brain shows innate potentials, that grows with training at school for example. Among these potentials, we find language, motricity and a wide sets of knowledge about the physical or social environments, including a number sense.

Babies, at six months, although not able to count, are nevertheless able to discriminate between quantities, and have expectations regarding quantity combinations. If we put together 3 apples and 3 apples in a box, babies expect to see 6 apples in it. If they are shown the full content but see only 3, babies are surprised.

We, Humans and animals, seem to have a innate number sense. What we learn is only representing and manipulating quantities using systems of signs (language, numerical systems) and calculation strategies (arithmetic operations, algorithms, algebraic structures).