Have you ever looked down at your hands (perhaps while they were being painted in a nail salon) and thought: why do we have nails? One of the mysteries of human evolution, scientists are still debating whether or not they're a leftover, flattened version of claws, or a completely separate adaptation.
When you think of all the things your fingernails help do, it makes sense that evolutionary adaptation didn't eliminate them (unlike the tail). You can peel an orange easily, undo knots, scratch an itch, and pick your nose, all with the help of fingernails. They can even function as an early warning sign of potential malnutrition or health risks.And how about toenails? Why do we have toenails? Early humans were thought to use all four limbs for climbing, and toenails definitely help with gripping (think about longer, thick, claw-like nails that early humans would have had). Useful back then, but why do we still have toenails? Why do humans have nails, period? Read on to discover all the fascinating reasons why humans have nails!
Fingernails May Have Inspired Early Weapons and Tools
Early Homo sapiens didn't have a whole lot to work with, weapon- and tool-wise. Rocks and primitive spears, sure, but sometime they had to use their bare hands. That's where the fingernails come in.
Colin McGin argues in his Prehension: The Hand and the Emergence of Humanity that early humans drew inspiration from their fingernails: "the fingernails themselves provide an excellent prototype for tools designed to score and tear - the ingenious early human just needed to make sharper and more powerful nail-like implements."
It's an intriguing and romantic thought: early humans, inspired by their own bodies to create an extension of their bodies.
Reasons Why We Still Have Toenails Are Hotly Debated
Some in the scientific community insist that toenails are, in fact, useful. Perhaps they help us balance by exerting pressure on the toe and providing a counterweight. Or maybe they exist to protect our vulnerable toes when we aren't wearing shoes, especially given how recent a development protective footwear is on the timeline of human evolution. It's also possible we have toenails simply because our ancestors did - at some point in human evolution, toenails were functional and claw-like, but now they're something to trim and paint.
They Protect Our Fingers
The chief function of a fingernail is likely protection. Nails have no nerve endings, which is helpful, considering they're constantly in contact with our environment. It's argued that they evolved to be so tough in order to protect us from trauma both minor and major.
Horse hooves, similarly, have no nerve endings, allowing us to "shoe" them the way we do. We don't put our nails through that kind of punishment, but think how many more broken thumbs there would be in the world if the "shield" of a thumbnail wasn't there to absorb the blow of a hammer?
They Provide Support (By Getting Out of the Way)
Here's an interesting thought, courtesy of Tim Ryan at Penn State: our nails evolved into their flat and wide shape so they would be out of the way. Take a look at the above pic of the gymnast on the pommel horse: you can't do that with claws.
Ryan says that nails "allow the fingers and toes to be spread flat which provides a more solid support for the hands and feet during grasping." So along with added grip on branches in the treetops from broader fingertips, our lack of claws let primates and early humans use their palms for extra support.