When we apply this idea to infant development, it becomes clear that focusing on the sense of touch forces us to see the infant in a more active role where s/he has to “reach out” towards the world and comprehend an object outside themselves that is different from them. Through this investigation touch becomes a sense that provides organism with a sense of objects in the world. Through haptic touch an infant is able to understand that there other objects around her and that there are several features attached to those objects. This seems important for understanding commonalities between the development of infants in both apes and humans because the focus becomes the active role played by the infant instead of a passive one dependent on an active caregiver.
via The Impossibility of Hugging Yourself, or How Touch Opens the Doors of Perception in Apes and Humans | The Brains Blog.