Why Do Humans Have Fingernails?
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!
The Origin of Fingernails Is Hotly Debated
Are fingernails an evolution of claws or an unrelated adaptation? Scientists say their origins are murky, but archeological finds suggest that human fingernails broadened and flattened around the same time humans began using stone tools. The findings suggest that once we started using tools all the time, we no longer really needed nails for certain things, so they changed, radically. It makes sense: why use a fingernail to dig if you have a primitive shovel?
Today, we use tools way more than other primates - though there are some orangutans getting too clever for their own good - so it makes sense that our fingertips remain the broadest in the primate kingdom. You might say we evolved to need claws the least, so our claws followed suit and became very un-clawlike.
It's All About the Branches
Whether humans developed fingernails to support our broadening fingertips or if they were just a "side effect" of losing our claws is still unclear, but we're pretty sure we know which of our primate cousins first had fingernails: Teilhardina brandti, a six-inch-long primate from the Eocene that resembled a lemur (that's the gnarly claw of a black-and-white ruffed lemur pictured above).
Researchers believe T. brandti evolved its tiny nails - and in a sense, our nails? - to make it easier to grasp small branches, as well as hold on to food. They're the smallest "true" fingernails on record, but they may have offered a big advantage to T. brandti.
Fingernails Are Perfect for Certain Manipulations
We don't need fingernails to perform essential survival tasks, the way, say, a tiger needs claws, but they really come in handy sometimes, as we all know. For instance, they work for scratching, picking and peeling fruit and veggie skins, and cleaning certain body areas (such as the scalp). These everyday tasks would be a lot more time-consuming without fingernails.
The theory that humans using tools caused our fingernails to get less and less claw-like has support in the evolution of the so-called "grooming claw" or "toilet claw" in certain primates. Like it sounds, it's a specialized nail used for personal grooming. Perhaps the use of tools prohibited humans from evolving this nifty nail? Regardless, the nails we know and love (and chew) today still prove useful in a number of applications.
In the Distant Past, Fingernails Helped Humans Capture Body Lice
From an evolutionary standpoint, fingernails allowed early primates to more easily perform certain daily tasks, but unlike how we use them, fingernails really did help keep them alive. Grooming each other with their fingernails helped reduce skin parasites such as lice and also was a means of social bonding in the group (and we all know what that leads to).
Unfortunately, gorillas may have given early Homo sapiens one kind of lice that their fingernails were no match for: pubic lice. That doesn't mean anything "unnatural" was going on (not necessarily); we may have gotten them from living near gorillas or killing them for their meat.
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.