The reason people get prune-like wrinkly fingers when they have been immersed in water is due to a process controlled by the nervous system.
Scientists have now discovered that wrinkled fingers allow humans to better handle wet objects or objects underwater.
Published in the Royal Society's journal Biology Letters, researchers at Newcastle University analysed people taking objects out of water with wrinkled fingers and then again when they were not wrinkled.
Tom Smulders, author of the study, said: "We have shown that wrinkled fingers give a better grip in wet conditions - it could be working like treads on your car tyres which allow more of the tyre to be in contact with the road and gives you a better grip.
"Going back in time this wrinkling of our fingers in wet conditions could have helped with gathering food from wet vegetation or streams.
"And as we see the effect in our toes too, this may have been an advantage as it may have meant our ancestors were able to get a better footing in the rain."
Why dont' we have permanently wrinkled fingers?
The study participants picked up marbles of different sizes with wrinkled or non-wrinkled hands. They were faster at handling the marbles when they had wrinkly fingers.
They also found wrinkled fingers made no difference to moving dry objects, suggesting wrinkles on fingers and toes improve our grip on objects that are wet or underwater.
Smulders said: "This raises the question of why we don't have permanently wrinkled fingers and we'd like to examine this further. Our initial thoughts are that this could diminish the sensitivity in our fingertips or could increase the risk of damage through catching objects."
It used to be believed that wrinkly fingers and toes were caused by water passing into the outer layer of the skin, causing it to swell. It is now thought the process is an active one.
It is caused by blood vessels constricting below the skin - a process controlled by the autonomic nervous system that governs bodily processes such as breathing.
Being an active process suggests wrinkly fingers serve a function. However, it is only now scientists have been able to show what purpose prune fingers serve.