Count the arms

[7ronin]

Extra arms and legs are rare but perhaps occur more often than you might think. Consult any history of circus side shows and so called freak shows and you will see what I mean. In many cases both arms are fully functional although one is usually superior in terms of strength and mobility. Usually in the West today such cases are surgically corrected without publicity. Much more common are vestigal tails.

 

[GenMarshall]

Extra arms and legs are rare but perhaps occur more often than you might think. Consult any history of circus side shows and so called freak shows and you will see what I mean. In many cases both arms are fully functional although one is usually superior in terms of strength and mobility. Usually in the West today such cases are surgically corrected without publicity. Much more common are vestigal tails.

But were thoes extra arms on people from circus side show independently mobile or mearly "slave arms" (A slave arm in mechanics is an secondary arm that moves in conjuntion with the main arm)

 

[7ronin]

But were thoes extra arms on people from circus side show independently mobile or mearly "slave arms" (A slave arm in mechanics is an secondary arm that moves in conjuntion with the main arm)

Some of them were independently mobile although in most cases they were just "floppers." None of them were "slave arms" in the sense that they moved in tandem with the main arm.

 

[Erik Mesoy]

Well, Erik was talking about the brain adapting to new stimulus and growing to control the input.
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That's why I mentioned Erik's earlier discussion. I wonder if an arm will improve if its twin is removed.

Correct. But there may be some problems...

The extra arm is not on the blueprint for a normal human body. (Not saying anything about 'design'.) This may result in the slave problem CG mentioned, in that the arms won't be fully independent because one of them follows the other, or 7ronin's "floppers". (Apparently not the case here.) Another possibility is that the arms don't have full connectivity to the brain, and if the brain doesn't have a proper I/O connection, it has more difficulty adapting. Third, the nerves from the brain to the arm may split on the way, meaning that the arms will receive the same orders from the brain. (Squint at your nose and wave your arm - you see two arms, right?)

I don't know enough to say anything. The doctors know a lot better what's going on, and I can't influence them.

The interesting (some would say frightening) bit here is that grafts might be more reliable than adding limbs the "natural" way.

That was to catch your attention. Now open this PDF file.

He'll become a great martial artist someday. They'll have to create a whole new system to deal with him.

He will have a blockbuster career, winning match after match, until he is killed in combat by a shot to the kindney in 2031.

I don't recognize this reference. Is it a movie?

Anyway, back on topic:

Is the removal of one arm (they cannot determine the superior arm) a moral decision? Is this the modern version of cutting off arch-Angel's wings?

If I had a kid like that, I'd try to leave him intact. The reasons for not doing so are mostly peer pressure.
I'm imagining this kid getting an extra arm cut off, then twenty years later suing his parents for violating his body and not respecting diversity. Then there's a wave of lawsuits from similar children who were modified while they were young, at more or less the same time as bionics become popularly available.

Plus, aren't we messing with evolution? What if a third arm led to a huge reproductive advantage???

Well, this sort of thing is sometimes the raw material for evolution. The question is whether it's inheritable, and if it is, whether it's biologically compatible with "normal" genetic instructions. It might get overridden.



...and just because I have to say it: ZAPHOD BEEBLEBROX!

 

[The Last Conformist]

Well, this sort of thing is sometimes the raw material for evolution. The question is whether it's inheritable, and if it is, whether it's biologically compatible with "normal" genetic instructions. It might get overridden.

It's probably not genetic - if it were, you'd expect him to have two arms at each side.

Also, tetrapod forelimbs isn't the kind of organ that easily gets duplicated. While there's plenty of lineages that have lost one or both pairs of legs (aïstopods, caecilians, snakes, some other lizards, whales, and no doubt something I'm currently forgeting), none have got more.

Even among (conventional) fish, doubling of the pectoral or pelvic fins is unusual.

 

[Erik Mesoy]

This just in from talk.origins:

"And China lurches ahead in the arms race!"



@TLC: Thanks for the info. I'll have to lookup something in Six Wheels on my Dragon, where it talks about dragons being unlikely because they have three sets of limbs, and the possibility of doubling mutations.

 

[AL_DA_GREAT]

I want three arms

 

[Narz]

I don't recognize this reference. Is it a movie?

Nah, I just made it up.

 

[Perfection]

My views

Yes, three arms is unhealthy
Yes, one should be removed
Yes, it would be cool if it really worked

I count three arms.

That's funny. I counted five

Spoiler :