Touch is central to our experience of the world; it helps define us. We sense with our bodies the objects we encounter—the couch cradling us, the table colliding with our knees, the breeze fluttering at our cheeks. Nerves uniquely adapted for sensing a dizzying array of stimuli freckle our skin, sending their impulses racing to our spinal cords and into our brains. Touch orients us to the world; it also attunes us to each other. By studying these sensory nerves, which seem reserved for signaling a particular kind of touch, scientists are beginning to learn about the role touch plays during childhood development.
As newborns we exit from the womb craving touch. Even before birth, researchers think, touch is critical to fetal development. Before a fetus can see, smell, or taste, it can sense touch. At twelve weeks, prior to widespread myelination of developing nerve fibers, ultrasound videos show fetuses wriggling away from nudges to their mother’s bellies. And it appears that we are preprogrammed to understand which touches are pleasant and which are painful.