Why Do Fingernails Grow Faster Than Toenails
Fingernails are pretty handy tools, especially when it comes to back scratching and peeling those stupid little stickers off pieces of fruit. Toenails… meh. But one question that I’ve pondered for a while is why I have to cut my fingernails WAY more than I cut my toenails.
Thought it is still unclear, many scientists believe that nails used to be more like claws (and may have in fact just been claws) but flattened and widened when primates started using stones as tools and swinging from branches, so therefore had less of a need to use claws for things like digging or attacking a predator (or prey). The flattening also meant that these nails could get out of the way and allow primates to use the palms of their hands more easily.
Researchers are pretty sure that the first primate ancestor to have fingernails was the Teilhardina brandti, a small primate from the Eocene period that resembled a lemur. Nails proved pretty handy for our primate relatives for everyday behaviors like peeling fruits and veggies and picking lice and gnats off of each other (aka “prehistoric grooming”). While toenails have become much less relevant in our modern lives, it was only recently that humans started wearing shoes so toenails may not have had enough time to phase out just yet.
Semi-obvious when you actually think about it; most of the nail is actually dead. This is why it doesn’t hurt to clip your nails or when you accidentally get a small surface-level cut to the top of the nail. The only living part is the small sliver under the skin towards the rest of your finger called the nail matrix. This is also the only part that grows. Special keratin-rich cells are formed and push the cells in front of them forward towards the end of your nail. The nail plate (the thing we paint) is attached to a highly vascularized nail bed which is why the nail that is still attached to the finger is a similar color to the skin. Once the cells are pushed past the nail bed they lose the nutrients supplied by the nail bed, die, and turn white. This part is called the lunula.
Interestingly enough, the growth rate of a nail is directly related to the length of the bones in that finger. That means that your index fingernail actually grows slightly faster than your pinky fingernail! Additionally, fingernails grow up to 4 times faster than toenails. The growth rate of nails depends on a surprising number of factors such as age, sex, season, weather, diet, exercise, and other hereditary factors.
To my dismay, no one is 100% certain why fingernails grow faster than toenails, but there are two generally accepted theories. The first is called “terminal trauma” which is horribly named but essentially means that the more you use a digit, the faster the nail grows. Your body assumes that with greater use comes greater wear and tries to regenerate appropriately. I guess all my typing explains why I have to cut my fingernails more than once a week! Also, if you are right handed, your right fingernails will grow faster than your left since your dominant hand gets more use. Toes pretty much get to chill in their socks and shoes all day so the nails grow more slowly. I didn’t find any research on this but am curious to know whether earlier primates who walked on their hands and feet and used both for most tasks had nails that grew at a more similar pace.
The second theory suggests that nail growth directly corresponds with the amount of blood flow that a digit receives. Since your hands are closer to your heart than your feet, more blood will get pumped to your fingers than your toes causing more growth in the nails of the fingers. Research shows that nails grow more slowly in cold weather, when blood flow is restricted which also supports this claim.
So there you have it. Not totally satisfying but still interesting tidbits on nails that I definitely didn’t know before today. And one last note to leave you with… apparently there is an urban legend that nails continue to grow after death, but that is not true. The dead skin starts to shrink on the hands and feet which gives the illusion of nail growth. You’re welcome.
