A whimsical evolutionary question: cats with thumbs

[Nerys Ghemor]

OK...this is a science question at its heart, but it's also my time to be completely silly, so bear with me.

What got me thinking about it was this milk ad from the UK, about polydactyl cats: http://www.youtube.com/watch?v=h6CcxJQq1x8

Obviously there are a LOT of other things...a lot...that would have to occur from an evolutionary standpoint before any of the behavior in that commercial could occur.

But my question was this: is it possible that the right kind of polydactyly in cats--the kind that creates an opposable thumb without any damaging disorders--could be an example of the kind of evolutionary trait that might actually present a survival advantage in the wild? I know that most mutations are maladaptive, but some of the things I've seen videos of "thumbcats" doing (real ones, not the ones in the commercial) show them as having greater manual dexterity than cats with a normal paw. Could this actually be an example of a good mutation happening right before our eyes?

Might it even be an example of one kind of process (though certainly not the only option) as to how the great apes like ourselves came by our opposable thumbs?

Again, this is really a silly question more than anything. But I couldn't help but wonder.

Here are some examples of what a real-life cat with thumbs looks like:

http://www.youtube.com/watch?v=2hngBzDDyFE
http://www.youtube.com/watch?v=_9x-19KoEYo
http://www.youtube.com/watch?v=JiZQoy0Bsng

 

[RoJoHen]

I don't think it's a silly question at all, and frankly, I fear for our descendants if these thumbed cats continue to evolve into Cat People!

Cats are sneaky. They'd take over the world without us even knowing!

 

[Jadzia]

Nature is such a complex thing that it's hard to say what would be an advantage for a particular species, in a particular location, at a particular time. Here are some ideas:

Thumbs help us to grip things, but only really in combination with long fingers that can wrap around an object.

Thumbs and long fingers might be of little use to a creature that spreads it's body weight over it's four legs when walking. They might be prone to physical damage, prone to getting stuck in crevasses, and vulnerable to frostbite in cold weather. Evolution might select against thumbs and long fingers if this damage risk is significant. However, creatures that walk upright or that put most of their weight on their hind legs, might benefit from thumbs because of the greater dexterity it gives them to hold things.

Thumbs might also be a disadvantage for an agile/nimble creature because the ball of the thumb can end up taking too much weight, especially if the body is off centre.

Creatures that pounce to catch their food launch themselves from their 5 fingers. But having a thumb means they'll be launching themselves from only 4 fingers. Surely that means they'll not be able to launch themselves as far, and might not be able to catch their prey?

 

[RoJoHen]

Creatures that pounce to catch their food launch themselves from their 5 fingers. But having a thumb means they'll be launching themselves from only 4 fingers. Surely that means they'll not be able to launch themselves as far, and might not be able to catch their prey?

What if they have 5 fingers AND a thumb?!

 

[Bill Morris]

For a mutation to carry on, it must afford an advantage in likelihood to procreate. Tomcats fight over females, and if having a thumb gives a tom the ability to masterbate, he may be less likely to engage in cat fights and carry on the line. But if he uses that thumb to wield an ice pick, well, . . .

 

[Nerys Ghemor]

Creatures that pounce to catch their food launch themselves from their 5 fingers. But having a thumb means they'll be launching themselves from only 4 fingers. Surely that means they'll not be able to launch themselves as far, and might not be able to catch their prey?

What if they have 5 fingers AND a thumb?!

That's what I believe cats usually have, when they get the "thumb" mutation: 5 digits plus a thumb.

As to how cats with this mutation bear their weight, I'd have to find a video of one walking to see how much of their weight is on their thumb joint.

Or does anyone own such a cat who can say?

(I think that there are other animals with opposable thumbs that are not great apes as we and gorillas are, though...I'd have to watch some of those videos, too.)

 

[Deranged Nasat]

(I think that there are other animals with opposable thumbs that are not great apes as we and gorillas are, though...I'd have to watch some of those videos, too.)

Several marsupials, an African rodent, and (not very helpfully if you want footage) several therapod dinosaurs, all have/had opposable digits or at least something approaching it. Not sure if technically they count as thumbs. I think most of the marsupials are arboreal though, I'm not sure if the rodent is a ground-dweller. And of course the therapods were bipedal...

I don't know if I've heard of any quadrupal terrestrial animal other than cats that develops this particular thumb mutation.

 

[Finn]

I've seen a book (heavily illustrated) that appeared to be about how mammals would evolve after Humanity vanishes (before Discovery Channel did that angle). Among them was a entire group of cats that developed that trait as well as a simian-like posture. As you can imagine, they were lethal, more lethal than any cats we have today...

I found that book on amazon.com

 

[Deranged Nasat]

I've seen a book (heavily illustrated) that appeared to be about how mammals would evolve after Humanity vanishes (before Discovery Channel did that angle). Among them was a entire group of cats that developed that trait as well as a simian-like posture. As you can imagine, they were lethal, more lethal than any cats we have today...

I found that book on amazon.com

Ah yes, those are the ones who evolved to prey specifically on primates, weren't they? "Strigers", I think they were called?

 

[MLJames]

Yup, and the book said they evolved from "the last of the true cats" about 30 million years before the book's setting (which was 50 million years from now). I picked that book up when it came out thirty years ago; loved it and the one the author did set in a modern world where the dinosaurs never went extinct.

 

[little_chris]

What would happen?

http://homepages.nildram.co.uk/~polymorp/rdpic/calandercat.jpg

 

[Pavonis]

For a mutation to carry on, it must afford an advantage in likelihood to procreate.

Actually, as long as a mutation doesn't prove to be a detriment to procreation, it will be passed on. Mutations don't have to be advantageous at all.

 

[Meredith]

You would get these:

 

[P0sitr0nic]

My first cat had thumbs... i thought very much the same thing.