Scientists know a lot about the body, but they don't know everything. Take, for example, the pruning that occurs when you spend too much time in the water. Scientists don't know why these wrinkles occur only on the hands and feet.
A recent study in Brain, behaviour and Evolution suggests these wrinkles are there for a reason - they may help you grip things. The wrinkles all have the same basic pattern of grooves that move apart from each other as they extend away from the fingertips. These grooves let water drain from your hands and could provide additional surface area that would improve your grip in wet conditions. [ Brain, behaviour and Evolution via NYT; Image from Afronova/Shutterstock]