I mean, I don’t see what they do that some tougher skin couldn’t do. Plus, with tougher skin on it, you wouldn’t have the issue where if you get a bruise under there it stays there for ages. I’d say it’s just the first thing to evolve, except it seems like tougher skin would evolve first, being less complicated.
A healthy fingernail has the function of protecting the distal phalanx, the fingertip, and the surrounding soft tissues from injuries. It also serves to enhance precise delicate movements of the distal digits through counter-pressure exerted on the pulp of the finger.[2] The nail then acts as a counter-force when the end of the finger touches an object, thereby enhancing the sensitivity of the fingertip,[9] although the nail itself has no nerve endings. Finally, the nail functions as a tool enabling a so-called “extended precision grip” (e.g., pulling out a splinter in one’s finger), and certain cutting or scraping actions.
We didn’t evolve finger and toenails. The thing we evolved from already had them.
Okay, then why did they? That doesn’t really fix things, just move it backwards to whenever they first evolved.
Most mammals and reptiles make a lot more use of their nails than we do.
I’ve always thought that fingernails and toenails are modifications of claws. As such they are basically vestiges of things that gave our evolutionary ancestors a great survival advantage, but are now, as said upthread, mostly superfluous.
They look pretty painted sparkly pink.
I actually think humans need fingernails to survive today. They can be rather deadly weapons, used properly.
We evolved fingernails shortly after becoming intelligent enough to use rocks as a hammer.
That is my hypothesis.
Our past claws have evolved to fingernails. Other animals continue to evolve better claws, or not , as it suits them to survive. It seems an obvious evolution to have some hard extension to ones paws/claws or whatever, if you need to dig or defend. As your evolution progresses the claws adapt. An awful lot of animals need to dig. For food. To build a den. For defence/attack. Our claws seem to have adapted very well. We do much finer work with our hands. I find that when I have clipped my nails too short, I have harder time doing a lot of things.
As mentioned, fingernails are modified claws. They are a derived character of all primates. Claws themselves go back to very early reptiles. Nails and claws are made by specialized epidermal cells, meaning that they are…tougher skin.
Mammals aren’t descended from reptiles - but it’s likely that the basal amniote ancestor of both reptiles and mammals had claws.
Many primates use fingernails to pick at parasites, including on each other as a social thing. Maybe that has guided recent evolution?
Most recent common ancestor was therapsids, and pelycosaurs before them … had claws. Likely the first tetrapods to evolve to slither about on land had claws. Obvious functionality to them.
So the question is more why we lost full claws and stopped at the relatively vestigial nails.
There is no answer to why specific to an evolved characteristic. The underlying why is always because of chance or an advantage to survival and reproduction.
It is reasonable to ask why an evolved characteristic provides an advantage to survival and reproduction, but that doesn’t always produce a clear answer. With fingernails it could have been some ancestor of ours for no particular reason did not continue to produce the gene for sturdy claws but also had a gene that led to better brains, or perhaps stamina to point to a couple of examples. We don’t really know if the diminution of claws into fingernails provided an advantage directly, indirectly, or at all.
Not according to the wikipedia article quoted by @Joey_P in the first reply in the thead:
A healthy fingernail has the function of protecting the distal phalanx, the fingertip, and the surrounding soft tissues from injuries. It also serves to enhance precise delicate movements of the distal digits through counter-pressure exerted on the pulp of the finger.[2] The nail then acts as a counter-force when the end of the finger touches an object, thereby enhancing the sensitivity of the fingertip,[9] although the nail itself has no nerve endings. Finally, the nail functions as a tool enabling a so-called “extended precision grip” (e.g., pulling out a splinter in one’s finger), and certain cutting or scraping actions.
Of possible interest to this discussion.
Remember that we have the habit of assuming that our modern human ancestors lived the same way we do today. Yes, we do use our fingernails for some things, but if you were to watch a farmer or a hunter gatherer go about their different lifestyles I think you would find that nails are pretty useful to them. Peel fruit, scrape materials, split leaves to extract fibers to weave…the list goes on and on. I am pretty sure that our ancestors within just a few centuries ago found nails to be pretty darn handy. And they didn’t even have a local pedicurist to go to when needed.
Fingers still give shape and structure to our fingertips, which allow us to better utilize our amazing hand abilities.
As far as toenails go - even more needed than fingernails.
Just because we don’t need them quite as much as in previous centuries doesn’t make them go away…evolution doesn’t work that way.
Probably not, because amphibians don’t have them:
The only amphibians to bear claws are the African clawed frogs. Claws evolved separately in the amphibian and amniote (reptiliomorph) line.
From:
It does seem you are likely correct.
Claw-like structures have evolved many times in vertebrates, invertebrates, and even plants. True claws seem to have first evolved around the origins of amniotes. Claws are rare in amphibians, but extremely common in reptiles, birds, and mammals, which suggests that early tetrapod claws might have been a key feature among the first amniotes as they explored habitats farther from the water’s edge.
Jorge Luis Borges wrote a very short essay on toe nails. I like the concluding sentence:
“And when I am tucked away in Recoleta, in an ash-colored house bedecked with dry flowers and amulets, they will still be at their stubborn work, until corruption at last slows them - them and the beard upon my cheeks.”
NB: Recoleta is the best known cemetary in Buenos Aires.