After spending a lengthy period in water, you may notice a particular phenomenon occur – wrinkled fingers and toes! A common misconception is that pruney digits are caused by water soaking into our skin, presumably by osmosis. In reality, furrowing in our fingers is caused by constricting blood vessels by the nervous system. But what could be the evolutionary purpose?
One hypothesis in 2011 was that that grooves in wet fingers would allow humans to grip surfaces more easily. Newcastle University researchers in England tested this theory, recording the time it took for subjects to move objects with dry fingers and with wet fingers. Every subject moved objects faster with wet fingers, suggesting that furrowed fingers can better handle moist items – an evolutionary advantage.
However, the study has not revealed how furrows improve grip. Neurobiologist Changizi from Idaho states that there may be other factors for improved grip, such as stickiness or oils. Scientists posit that the furrows may cause friction or increase flexibility. They also put forward a possible disadvantage of having pruney skin: grooves may decrease sensitivity or get caught on things. Further research to come!
What do you think about these theories?