Why Do Humans Have Fingernails?

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.

      • 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?

         
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      • 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.

         
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      • Nails Are Indicators for Certain Health Conditions

        Doctors can identify certain health conditions by looking at someone’s nails. Beau’s Lines, for example, are nail ridges that can be a result of poorly controlled diabetes or a heart or liver condition, among other things. 

        Researchers say even bowel diseases can be “seen” in the nails: “clubbing,” for example, indicates pulmonary or inflammatory bowel disease. Spoon-shaped nails, meanwhile, may be a sign of anemia.

         
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      • Nails Are Also Indicators of Overall Health and Nutrition

        Fingernails and toenails can indicate the presence of certain diseases, but may also point to overall problems with your health and nutrition. For example, if nails are weak and brittle, you may need more keratin. Vitamin deficiencies can also cause issues with your nails. 

        Research has shown that not getting enough vitamin B12, for example, can cause brown-gray nail discoloration. Pink or red nails that got that way without nail polish suggest malnutrition, which is ironic, considering that those colors are considered healthy and sexy when artificial.