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-   -   why do we have fingernails instead of claws? (https://boards.straightdope.com/sdmb/showthread.php?t=792768)

Machine Elf 05-10-2016 01:58 PM

why do we have fingernails instead of claws?
 
Humans, chimps, and gorillas (and I suppose some other primates I don't know about) all have fingernails instead of claws. Claws actually seem pretty useful, so why did we evolve away from them?

Senegoid 05-10-2016 02:05 PM

Especially retractable claws (or fingernails). Why can't we have that too?

Morgenstern 05-10-2016 02:08 PM

Quote:

Originally Posted by Senegoid (Post 19320844)
Especially retractable claws (or fingernails). Why can't we have that too?

Makes it way too hard to pick your nose.

Machine Elf 05-10-2016 02:10 PM

Quote:

Originally Posted by Morgenstern (Post 19320847)
Makes it way too hard to pick your nose.

I'd probably be willing to trade that for the ability to slash through packing tape (or potato chip bags) without a knife.

leahcim 05-10-2016 02:16 PM

I've read that having flat fingernails gives some rigidity to the fingertip, which is useful for grasping.

Colibri 05-10-2016 02:16 PM

Probably because our primate ancestors relied on opposable thumbs (and toes) to climb instead of climbing with claws like squirrels. They climbed mainly on smaller branches that they could get their entire hands around, rather than clinging to trunks by claws. With such a climbing strategy long sharp claws just get in the way.

Most primates, even primitive ones, have nails instead of claws on their digits, although lemurs retain a claw on one toe for grooming.

Marmosets, which climb up trunks like squirrels, have claws on most toes but have a nail on the thumb.

Some other animals that climb using opposable digits like opossums have a nail on the thumb but claws on the other digits.

Atamasama 05-10-2016 02:48 PM

Quote:

Originally Posted by Machine Elf (Post 19320855)
I'd probably be willing to trade that for the ability to slash through packing tape (or potato chip bags) without a knife.

With bulky claws you'd have trouble holding a knife, or a gun. I feel more confident in my ability to use tools, thanks.

Grow out and maintain one fingernail and you can use it for simple things like opening chip bags and packing tape. You don't need to be Wolverine to do that.

panache45 05-10-2016 04:37 PM

And why don't we have wings or infra-red vision, while we're at it?

Evolution doesn't work that way. It doesn't decide that something is better, then evolve toward it. If a given mutation doesn't occur, it doesn't happen.

Jophiel 05-10-2016 06:05 PM

Quote:

Originally Posted by panache45 (Post 19321204)
And why don't we have wings or infra-red vision, while we're at it?

Evolution doesn't work that way. It doesn't decide that something is better, then evolve toward it. If a given mutation doesn't occur, it doesn't happen.

True, but if we evolved from little rat creatures or something similar then it seems likely that our proto-primate ancestors at some point went from claws to nails. So the question then is why were nails advantageous enough to become the norm?

panache45 05-10-2016 06:31 PM

Quote:

Originally Posted by Jophiel (Post 19321434)
True, but if we evolved from little rat creatures or something similar then it seems likely that our proto-primate ancestors at some point went from claws to nails. So the question then is why were nails advantageous enough to become the norm?

There's a logical step missing in your thinking. Hint: "went from claws to nails" does not necessarily imply "advantageous," apart from other possible factors.

puzzlegal 05-10-2016 06:52 PM

Eh, the odds are that nails to claws was advantageous.

Jophiel 05-10-2016 08:35 PM

Quote:

Originally Posted by panache45 (Post 19321481)
There's a logical step missing in your thinking. Hint: "went from claws to nails" does not necessarily imply "advantageous," apart from other possible factors.

If you're going to answer questions, then answer them instead of giving too-cute "hint" nonsense to let everyone know how smart you are :rolleyes:

Asking why we don't have wings or infrared vision isn't the same because there was never a point along our known evolutionary chain where we DID have wings. So while it might be handy to have wings or six arms or acid breath, it's not the same as asking why we went from a trait we used to have (claws) and adapted to have a different trait (nails) instead as our primate ancestors evolved.

Hail Ants 05-10-2016 08:49 PM

I would hazard a guess that it has something to do with primates not being carnivores. And proto-humans only became major carnivores (or omnivores) by way of tool-making and weapon building, something that claws are a detriment to doing.

Colibri 05-10-2016 08:53 PM

Quote:

Originally Posted by panache45 (Post 19321204)
And why don't we have wings or infra-red vision, while we're at it?

Evolution doesn't work that way. It doesn't decide that something is better, then evolve toward it. If a given mutation doesn't occur, it doesn't happen.

This is not particularly insightful. In this case, these are just two forms of the same structure, not an entirely de novo organ. It's entirely reasonable for nails to have evolved from claws without any major mututaion.

Quote:

Originally Posted by panache45 (Post 19321481)
There's a logical step missing in your thinking. Hint: "went from claws to nails" does not necessarily imply "advantageous," apart from other possible factors.

Yeah, in this case it pretty much does. Read my post. We can identify the reasons that primates don't have claws.

There's a whole field of evolutionary biology predicated on the idea that we can identify the reasons why particular characters evolve.

Colibri 05-10-2016 08:58 PM

Quote:

Originally Posted by Hail Ants (Post 19321754)
I would hazard a guess that it has something to do with primates not being carnivores. And proto-humans only became major carnivores (or omnivores) by way of tool-making and weapon building, something that claws are a detriment to doing.

No, many prosimians, similar to ancestral primates, are mainly insectivores and also eat small vertebrates. Claws would be useful for catching prey. And there are many tree climbing non-carnivores like squirrels that have claws. Nails evolved in ancestral primates due to their climbing style, not diet.

Raguleader 05-11-2016 12:24 AM

My understanding of evolution is that certain traits evolve because they did not actively prevent individuals from getting laid.

So it's safe to say that humans and other primates have claws because somewhere back in our developmental tree, it was decided that amorous claw marks were best avoided.

Isamu 05-11-2016 01:25 AM

Quote:

Originally Posted by Colibri (Post 19321760)
There's a whole field of evolutionary biology predicated on the idea that we can identify the reasons why particular characters evolve.

Why did Bert and Ernie evolve? To fill an empty void in our lives?

Isilder 05-11-2016 04:13 AM

Quote:

Originally Posted by Colibri (Post 19320876)
Probably because our primate ancestors relied on opposable thumbs (and toes) to climb instead of climbing with claws like squirrels. They climbed mainly on smaller branches that they could get their entire hands around, rather than clinging to trunks by claws. With such a climbing strategy long sharp claws just get in the way.

Most primates, even primitive ones, have nails instead of claws on their digits, although lemurs retain a claw on one toe for grooming.

There's a few more important points..
* being able to climb more things. Not just trees, its vines , rocks, muddy slopes and so on.
* More important ... being able to use weapons and tools.. back to those rocks...
Being attacked by a tiger ? or large dumb primate ? pick up a weapon..

As ACC said (and DNA references) 'bang the rocks together guys!"...

Lukeinva 05-11-2016 06:15 AM

Because we trim our nails. If we didn't they'd grow into claws.

Chronos 05-11-2016 07:00 AM

There's a difference between a long fingernail and a claw. Claws are narrower, thicker, more curved in cross-section, and pointier. No matter how long you let a fingernail grow, it'll never get those traits.

Jonathan Chance 05-11-2016 09:01 AM

A man can dream!

Colibri 05-11-2016 10:47 AM

Quote:

Originally Posted by Isilder (Post 19322239)
* More important ... being able to use weapons and tools.. back to those rocks...

Probably not a major consideration for lemurs, bushbabies, and tarsiers.

Once again, we have nails because our ancestors had them. They evolved tens of millions of years before the first tools were made. Tool use was not a consideration in their evolution.

Doughbag 05-11-2016 10:47 AM

The function of a nail is different to a claw.

The claw is an aid in gripping to surfaces and holding prey in place or a weapon altogether.

The nail is there to protect your fingertips (or in some mammals it turned completely into a hoof) and as a tool to hold or pull small things (splinter) that would not be possible to do with claws.

Just think of the things we do and touch with our hands and the fingers attached to them, some of those activities or places where they touch - I certainly wouldn't wanted claws anywhere near there.

furryman 05-11-2016 02:35 PM

Quote:

Originally Posted by Lukeinva (Post 19322296)
Because we trim our nails. If we didn't they'd grow into claws.

I always wonder how that East Indian guy grew the world's longest fingernails. He must have had somebody do everything for him. Mine break off all the time.

Chronos 05-11-2016 04:40 PM

In fact, I think that was the point of the exercise: By growing such long nails, he's proving that he has people to do things for him. It's a status symbol.

And while tools didn't drive the evolution of fingernails, it's possible that our pre-existing fingernails were one of the traits that enabled us to become the premier tool-users on the planet.

Senegoid 05-11-2016 08:57 PM

Quote:

Originally Posted by Chronos (Post 19323736)
In fact, I think that was the point of the exercise: By growing such long nails, he's proving that he has people to do things for him. It's a status symbol.

OTOH, I have a friend, about my age, comfortably (financially) retired, who is growing claws to rival Howard Hughes's legendary talons. He's become horribly depressed in recent years, and I think he's simply not taking care of himself. (There's much other evidence of that too.)

furryman 05-12-2016 12:51 PM

Quote:

Originally Posted by Chronos (Post 19323736)
In fact, I think that was the point of the exercise: By growing such long nails, he's proving that he has people to do things for him. It's a status symbol.

And while tools didn't drive the evolution of fingernails, it's possible that our pre-existing fingernails were one of the traits that enabled us to become the premier tool-users on the planet.

Actually, I read somewhere that being in the Guinness is a very popular hobby in India. Maybe status plays into it as well.


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