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The evolution of wrinkly fingers

Wrinkly fingers. They prevent you from soaking for hours in a bath or spending that extra time in the pool on a summer’s day. Well it turns out humans have evolved to have wrinkly fingers for a reason!

Wrinkly fingers experiment. Source: Kareklas K et al. Biol. Lett. 2013;9:20120999

Wrinkly fingers experiment. Source: Kareklas K et al. Biol. Lett. 2013;9:20120999

A group of scientists at Newcastle University in the UK found that wrinkly fingers help us get a better grip on wet objects.  This study, published in Biology Letters last week, investigated the speed of moving wet objects with wrinkly fingers.

Here’s how the simple experiment went:

  • A group of participants moved marbles in water from one location to another
  • The time taken to move the marbles was recorded
  • The same group of participants soaked their hands in warm water for 30 minutes
  • They repeated the experiment of moving the marbles in water
  • The time taken to move marbles was recorded

The scientists concluded that the group with wrinkled fingers were able to move the marbles 12% more quicker than the group with normal fingers.

An explanation for this mechanism is evolution. Evolution describes the way populations of living organisms change over time due to changes in genetic traits that are passed on through generations. In terms of survival of the fittest, it is thought that humans with wrinkly fingers would have been more likely to gather food from wet vegetations and streams, as well as retain shelter in the rain – hence survive and out-live any humans without wrinkly fingers.

So why aren’t our fingers wrinkled all the time? Clues suggest that when fingers are wrinkly you can lose sensitivity in the finger tips and the skin is more likely to get caught on objects.

The next step for science is to figure out HOW wrinkly fingers allow us to have better grip on wet objects. The scientists propose two ideas that can offer an explanation:

  1. The treads that form on the fingers, just like the treads on your car tyres, work to channel water away allowing for better grip on wet objects
  2. The properties of the skin, such as flexibility and better friction, change with the exposure to water leading to more efficient grip and handling of objects

Regardless of the reason, I will now appreciate my fingers much more when wrinkled.

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