Long before we learn how to speak or read an alphabet, we grasp and feel our way around the world, and listen to our bodies to discern between pleasure and pain. Skin is the largest organ of the human body, and houses receptors that perceive what we touch externally, but understanding the mechanisms that control and communicate the sense of touch and feel inside our bodies has long remained a bit of a mystery—though researchers have begun to crack the code over the past 10 years.