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22775.  Thu Aug 11, 2005 11:27 am Reply with quote

This might be fun: something on left-handedness vs right-handedness. The question might be in the form of a challenge:

Imagine that we have made contact with an alien civilisation. We can send them radio signals and they can understand what we're saying, but we can't send any kind of image or writing. How would we explain to them which is left and which is right?

Apparently this is impossible to do.

Other lefty/righty stuff:

1. About 1 person in 10,000 has all his internal organs arranged in a mirror image to the norm (ie heart on the right, etc). This condition is called situs inversus and is entirely 'normal' and has no medical consequences.

2. Fetuses who suck their left thumbs in the womb grow up right-handed and vice versa (so we know that handedness is inherent, not conditioned).

3. It is thought that no-one is truly ambidextrous (ie equally adept at everything with either hand), although quite a lot of people are mixed (eg they write left-handed but throw a ball right-handed).

4. Although no specific gene or bit of DNA has been established as responsible for handedness, it does appear to be a matter of heredity because it has been established that two left-handed parents are more likely (though not certain) to have left-handed offspring.

5. Surveys of musicians, designers, mathematicians, dyslexics and stutterers all show higher than usual incidence of left-handers. (Chris, you're in two of those categories that I know of - are you a lefty?)

All this from an item in Radio 4's Material World science programme, 11/8/05, with Lewis Wolpert and Prof Chris McManus.

22792.  Fri Aug 12, 2005 5:57 pm Reply with quote

I am right-handed, but oddly although I write right-handed, I throw a frisbee left-handed (nd many other strange things like tying knots, crossing arms, etc). I think cultivating musical proficiency (should I ever manage it) does make one very much more skilled at using the 'weaker' hand, especially independently of the 'stronger'. Pianists and drummers get this a lot.

I imagine it would be impossible to find the cause of handedness, although it makes a lot of sense to think that it's cultural transmitted by parents, simply because the way around that various articles are placed in a house (or the way around that objects are offered to a child, to be 'helpful') will almost certainly affect which hand a child will use to pick them up.

For example, I always pick up the kettle with my right hand because my wife is right-handed and leaves it that way (as do I). What you get used to doing is what you get used to doing, and I expect this is why lefties beget lefty children more often. It doesn't happen every time because we're in a right-handed world, which sometimes tips the balance, especially with bolshie teachers, I've heard.

I might try to resurrect that 'Alanine' thing about handedness because that was quite interesting. Well, I thought so. :-)

22807.  Sun Aug 14, 2005 5:16 pm Reply with quote

it makes a lot of sense to think that it's cultural transmitted by parents

Yes, it does, but the people on the programme I got that stuff from were clear that this is not the case; they cited the fact that choice of thumb to suck in the womb is a reliable predictor of handedness when out of it as evidence that handedness is inherent.

22826.  Mon Aug 15, 2005 6:34 am Reply with quote

A quick sojourn to the site this lunchtime, and I thought you’d be interested in this story from ABC from February this year.

You often hear long lists of famous left handed people in the context of “WOW! Look at all these people who are famous AND left handed”.

Personally I always think that the number of famous lefties is disproportionately small considering the number of famous people there are, but there you go.

On a personal note, I have always found it easy to teach myself to do things left handed, but can’t do them naturally. I often play pool or golf left handed when the situation dictates and at Uni I taught myself to make lecture notes left handed, but now when I try it, it just looks like indecipherable scrawl.

Anywho, here’s the article on left vs right, there’s a lot of anecdotal evidence in this study, but even so, to imply that the sinister lot are linked to murder rates could be quite funny.

They found strong support for the idea that, at least in primitive societies with higher levels of violence, lefties thrive.


Statistics show left-handed people are more likely to be schizophrenic, alcoholic, delinquent, dyslexic, and have Crohn's disease and ulcerative colitis, as well as mental disabilities. They're also more likely to die young and get into accidents.

Researchers in France recently took an interest in the disproportionately high number of left-handed athletes who thrive in sports involving direct one-on-one contact, such as baseball (think Babe Ruth), tennis (think John McEnroe) and boxing (think Oscar de la Hoya or the fictional Rocky Balboa).

Charlotte Faurie and Michel Raymond of the University of Montpellier in France figured the same reason so many left-handed people are successful in such sports could also explain a possible higher success rate among lefties in primitive combat.

This means that, back in the days when fighting was an important part of survival and winning mates, the rare left-hander may have come out on top more often.

Clearly more searching is required, but I think there could be fun in finding a left handed guest and telling them they are more likely to be schizophrenic, alcoholic, delinquent, dyslexic and a murderer.

22832.  Mon Aug 15, 2005 9:30 am Reply with quote

I suppose the success in sports & fighting is easily explicable in that left-handers get lots of practice in confronting right-handers, whereas right-handers get very little practice confronting left-handers. That is, they don't need to be 'better' at the sport to succeed.

22844.  Tue Aug 16, 2005 10:14 am Reply with quote

Chris has an interesting point about music. I play guitar and bass, as well as some piano, and I am right handed - all of these instruments, particularly the guitar and bass, for me, involve being far more creative with the left hand. Chord changes, solos and so on, all require great skill in the left hand department.

Picking and strumming - thats all the right hand is good for.

So why then do right handers naturally gravitate towards using their left hand for the hard work? and visa versa..

Very odd. Or perhaps not, maybe it's riddled with logic.

28596.  Thu Oct 27, 2005 5:33 pm Reply with quote

Hi folks

Not posted here in ages, but thought I would restart.

It turns out that you could explain left and right. Thing is 2 chaps won a nobel prize for the answer. Something to do with magnetic fields, Cobalt and Asymetric release of electorns.

This link may explain it better than I can

and as you may guess from this post, I am right handed

28597.  Thu Oct 27, 2005 5:45 pm Reply with quote

Going back to brackett's point about playing the guitar, violin etc - that's puzzled me too. Why, given that most people are right-handed, have these instruments been developed to give the hardest role to the weakest hand? Any musicians know about this?

Incidentally, aren't a lot of chemicals left or right 'handed'? The word 'chirality' springs to mind, but I don't know much about it.

28603.  Thu Oct 27, 2005 6:50 pm Reply with quote

Morkris, thanks for that link, which is to the presentation speech for the 1957 Nobel Physics Prize. The relevant bit for our purpose is this:
Let us assume that the magnetic field is created by means of a coil placed like a spool of thread on a table, and that the electric current is flowing counterclockwise in the wire. Then the north poles of the cobalt nuclei will be directed upwards. The experiment, now, gave the result that the electrons from the radioactive process with this arrangement were preferentially thrown downwards towards the floor. From this it follows unambiguously that the process lacks that right-left symmetry, which one had earlier assumed. Thus, by means of this experiment it could be explained to a person, who did not know it - let us say an inhabitant of a distant stellar system - what we mean by right and left. In fact, it would be sufficient to ask him to arrange the experiment so as to make the preferential direction of the electrons point downwards. The current will then have the same direction as that in which he has to turn at the command "left face".

Now I'm not about to argue with Prof OB Klein, but I have to say that I don't understand what he means here. Let's say that this device is on a table, as he postulates, and that I am on one side of the table and you are on the other, facing me. Now we do the experiment, the electrons duly point downward, and the current runs to the left for me, but to the right for you, surely? Which leaves us no better off because we have no way of knowing which of us is on the correct side of the table.

The other thing is, how do you explain 'counterclockwise' to the aliens without using the terms 'left' and 'right' in the first place?

As I say, I'm sure he wouldn't have made this assertion lightly, so I don't question it - I just don't see what he means.

28615.  Fri Oct 28, 2005 2:24 am Reply with quote

This thread is giving me a mild case of déjà vu - didn't we bounce the subject of handedness around before, from a starting-point which had to do with the directions of snail-shell spirals?

I'll see what a Search will bring up.

28620.  Fri Oct 28, 2005 3:20 am Reply with quote


The way i got this right in my own mind is this. Given that the definition of left and right is arbitrary, the point of the experiment is to ensure that the alien and you adopt the same arbitrary definition. Therefore if we can get the alien to replicate the experiement so that we are both doing the same thing (in this case standing with our back to the current for example) then given all the other conditions are the same then we have got a shared definition of left and right.

I do not have a nobel prize however so i probably have got this completely about face

28623.  Fri Oct 28, 2005 3:51 am Reply with quote

Clockwise and anti-clockwise are much easier than right and left to define because the universe exhibits rotational asymmetries all over the place, and therefore it doesn't matter which side of the table you're on - clockwise is clockwise.

Say to the alien "get some crystalline feldspar (very simple chemical formula) and shine some light through it. The light's will turn clockwise (or anticlockwise - whichever it is, I can't remember).

From this, you can define left and right.

Prof Klein is merely saying that he's found another interesting outcome of his experiment - an asymmetry in the way that cobalt behaves in a magnetic coil (note that coils wrap clockwise or anticlockwise, not left or right), and could therefore be used as part of a verbal explanation to distinguish left and right.

28626.  Fri Oct 28, 2005 4:48 am Reply with quote

I still don't get it. I went and got some crystalline feldspar from Feldspars-r-Us and I'm holding it up to the light. When I hold it this way round the light rotates one way, and when I hold it the other way round it does the opposite. Or am I doing it wrong?

If it's easy to define 'clockwise' then it's equally easy to define 'right', isn't it? 'Right' is the direction in which the top of a clockwise rotation moves.

it doesn't matter which side of the table you're on - clockwise is clockwise.
True, but it does matter which way up you put your clock.

Quaint Idiot
28637.  Fri Oct 28, 2005 6:26 am Reply with quote

Some years ago I saw an Open University programme on this point, with people on earth trying to communicate left/right to an alien. It considdered various means which one might think could be used to distinguish left from right, but which didn't actually work. Then finally they came up with a solution ( I didn't understand it propperly, but it involved decay of K-zero mesons, if I remember correctly), and having used it to communicate with the alien they sent an astronaut into space to meet him/her/it. The astronaut held out his hand to shake, but the alien held out his left hand, and when they touched there was an explosion. Unfortunately the alien was from an anti-matter system and was studdying the decay of anti-K0-mesons.

Quaint Idiot
28642.  Fri Oct 28, 2005 7:13 am Reply with quote

Flash, if I understand the point you are missing in Klein's chirality demonstration it is that the axis of the coil is vertical, so the current flows clockwise whichever side of the table you view it from (provided, that is, that you do not view it from the underside, but up and down are easy enough to define).

To put it another way, if the electrons are propelled away from you the current in the coil as you are vewing it is clockwise, & vice versa.


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