And now for something completely different... This is a repost with a difference - it's an edited interview I did with London scientist Chris McManus way back in September 2007. This has a fond place in my heart, for it was the first proper freelance writing assigment that I did after winning the Telegraph's Science Writer award. This is where all the cool freelancing began. It was originally published on Nature Network, but I note that their news archives have disappeared. As such, here it is again.
McManus, a Professor of Psychology and Medical Education at UCL, is an expert on asymmetry and left-handedness. He won the Aventis Prize for Science Books in 2002 with his first book - Right Hand, Left Hand. Now, he's turned his attention to the rise and fall of left-handedness during British history.
About 11% of the British population is currently left-handed. But that wasn't always the case. Among people born in 1900, the proportion of lefties was just 3%. McManus and Alex Hartigan from University College London worked this out with the help of old films made at the turn of the 19th century and recently restored.
What made you want to study historical rates of left-handedness?
People have always assumed that the rate of left-handedness has been constant throughout history but it's never been properly explored. Recent data showed us that left-handedness was less common in people born at the beginning of the twentieth century than those born later, by a factor of four.
We wanted to find out what happened before that and why things changed. But of course, there's very little data. People have talked about left-handers in the literature since the time of Aristotle but they never say how many there were.
How did you find out?
It was a stroke of luck. We came across these wonderful films by Mitchell and Kenyon, made between 1900 and 1906, where they filmed people coming in and out of factories. They're wonderfully evocative films. You really get a sense of that late Victorian era.
We noticed that the people in the films waved whenever they saw the camera. My student, Alex Hartigan, went through this footage and recorded every time someone waved and which hand they used.
How long did that take?
Many, many hours. Alex watched an hour and a half of footage, frame-by-frame. He worked very hard and I don't think he realised how long it was going to take, so it was typical of any undergraduate project. The only differences was that all of his subjects had been dead for years!
We also needed a modern control group, and Alex had the brilliant idea of doing a Google image search for 'waving' He found tens of thousands of pictures and chose all the colour ones to make sure they were modern.
What did you find?
It was very clear that the rate of left arm-waving in the Mitchell and Kenyon films was much lower than in the modern data. And the older people were more likely to use their left arms than the younger ones, which is the exact opposite of modern findings.
We think this is evidence that the rate of left-handedness was already declining during the nineteenth century and was lowest for people born between 1870 and 1900.
What caused the decline?
It's not the standard explanations. Usually, people say that left-handers pretend to be right-handed because of social stigmas against left-handedness. But that's unlikely to apply to a natural spontaneous behaviour like arm-waving. And it's not because left-handers don't live as long as right-handers since the older people were more likely to be left-handed.
It might be because this period was the beginning of universal literacy and education. Left-handers wouldn't have been able to write as well with old-fashioned dip pens. In the regimented Victorian classroom, they would have stuck out and faced large social pressures or even physical punishment.
It could also be to do with the Industrial Revolution. Again, left-handers had visible trouble with operating large and heavy machinery that were almost certainly designed for right-handers. And in most societies, when you have a visible minority group, there's the possibility of stigmatisation.
Left-handers today still say that people have names for them or say they do things in strange ways, which makes them embarrassed. We have unpublished data to suggest that this could lead to left-handers having fewer children because they are less likely to marry or marry later. If there are genes involved, the rates of these would go down.
Have you considered non-social environmental factors?
It's possible, but people have looked for something like that for years and it never works. The strongest evidence against that idea is that in Britain, there's no social class variation in left-handedness. Most deleterious environmental factors vary across the social spectrum.
You used Google Image Search in your study - what do you think of the potential of the web as a research tool?
It's vast. On my book's website, 6,000 people have answered immensely detailed questionnaires on handedness and we've used them as control groups for other studies.
You can get lovely modern data sets. Recently, the BBC did a survey of 250,000 people who were asked, among other things, about their handedness. It showed that the rate of left-handedness varies across Europe and is highest in Belgium and Holland. You can only find out that sort of thing if you have a quarter of a million people filling in your survey.
Do you need to take special care to guard against bias?
In general, if you do a survey explicitly on handedness, you get more left-handers responding than usual, and that was true even in 1900. Left-handers seem three times more interested in handedness than right-handers!
But that's good - you get a larger left-handed sample and you can do more powerful statistics. Bias isn't a problem if you're aware of it and design it into your study.
Do you read any science blogs?
The only one I read is Improbable Research by Marc Abrahams, because I won an IgNobel prize a few years back. One or two of the anonymous things there are actually from me. I send them to Marc and say "What do you make of this? It's ridiculous!"
Do you have a favourite of London's science museums?
The Royal College of Surgeons. My art student friends and I sometimes go down there and draw these beautifully dissected human specimens. It's like a death-drawing class. The place really typifies London for me - it's a little corner of a quiet square with all this quality stuff lurking inside.
Do you have any new books coming out?
I'm been working on one about my first academic love - the psychology of art. It'll probably be out in two years. I do a lot of painting and drawing myself and I'm trying to make sense of the vast range of art from a scientific angle. I find the attitudes that some of my scientific colleagues have on art a bit embarrassing. It's rubbish to say that it's all evolutionary psychology and sexual selection.
And finally, are you right-handed or left-handed?
I'm right-handed and I can guess that you are too. Left-handers mostly notice the handedness of other people whereas right-handers don't.
Reference: McManus & Hartigan. 2007. Declining left-handedness in Victorian England seen in the films of Mitchell and Kenyon. Curr Biol 17: R793-R794.
More on asymmetry:
Although I'm (very) left handed myself, I'm not sure this is an accurate hypothesis. I would also interject that there is a temporal gradient of 'manners' at work here, in that there could quite possibly be an adopted mannerism of waving in a formalised manner, even though it seems an unconscious activity.
Consider a salute. The closest I've ever been to the military is the Boy's Brigade as a young youth. We had to do this stupid saluting nonsense. My first attempt at mimicking what they were teaching me were apparently wrong. They were using a different hand. Idiots. Soon, I had to as well, which felt wrong. Now, of course, I know it's wrong, but that's what I had to do. Now, if I had to salute someone I might not just use my left hand, I might use the other one instead due to indoctrination.
This might also have been prevalent at the time of the study sample, and more so among the younger recruits, too. After all, it was around that time that the idea of going off and fighting for a cause or the country you were accidentally born in was associated with ideas of valour and service and adventure. Exactly the opposite that most people coming out of the tail end of the 'great' war were to later imbue to our pre-beatnik society of free thinkers, but there you are - those were the assumed values at the time.
Talking of manners, it's a thing that I'm noticing in films across the generations. I wear a hat. Am I the only one in London to wear a hat? No, there's lots of others. But with wearing a hat there should be hat wearing etiquette, which is essentially lost. Yes, anyone can wear a fedora or a trilby today, but will they lift it up when they are in the presence of a woman? Will they take it off indoors? These mannerisms are a marker of a sharp divide of actual indoctrination pertinent to particular times. I suspect there's some of that at work here.
Uh, hand-waving is a social communication. The idea that it wouldn't be socially regulated is ridiculous.
i am left handed and i wave with my right hand. I don't think i could wave with me left hand.
Congratulations. You've overlooked entirely the educational system of Britain. In which violence and intimidation was used to promote right-handedness. Perhaps you've run into the word 'sinister'? The etemology can be traced to -- gasp -- left-handedness. My great-grandfather, grandfather and mother were all left-handed -- to begin with. Irish educators were even more devotely dedicated to removing this devilish trrait than their British contemporaries.
So -- continue your study, and present us with your "findings". But for all our sakes, don't look to your left!
I have to agree with Alice - I'm left-handed, and I would not be biased in which hand I would wave with. (For instance, I'm right-handed in my use of computer mouse. It started out as convienience when using shared computers, but I prefer it that way as it leaves my dominant hand to do other things. I would also argue that left-handers are better at ambidextrous activities)
This interview reminded me of the follow-up studies examining which side mothers hold their newborns on - it was found that the majority of both left- and right-handed mothers held their infants on the left, but gave different reasons as to why (can't find the reference - bother! - but it was along the lines of left-handers saying "it's my dominant hand" and right-handers saying that it left their right hand free).
I'm sure that has everything to do with parents forcing left-handed children to be right-handed. It wasn't that uncommon of a practice years ago, due to the negative stigma attached to left-handedness.
I think it's a little silly to judge handedness by how people wave, though.
I'm right handed, and I tend to carry things like a briefcase or a lunch bag, in my right hand. Therefore I would wave with my free, or left, hand. I speculate that would be the case whether my dominance is innate (it is) or forced, as it was on my elementary-school friends.
As another leftie, moreover one who was in kindergarten in 1950 (at 3yrs old) in the UK, I have to report I was quite intensely worked on to 'cure' my left-handedness. Techniques included rapping my knuckles with the edge of a ruler. Fortunately for my sanity, they were not completely successful. Writing remained leftie, because I could not stop writing mirrored text with my right hand. They eventually gave up on that. But table manners! Oy Veh! A gentleman _never_ uses the knife in his left hand! So I am still either confused or somewhat ambidextrous in most things other than writing. And I wave with my right hand because of it.
Which is to say, there was a social stigma associated with being a leftie well into the 50's in the UK. And I would surmise it started in the Victorian days, along with such woo as Phrenology, when behavioral conditioning to a norm became the Thing to Do with the kids. I guess it was confused with upward mobility possibilities. Left was not fashionable. it was, indeed, "sinister".
Social conditioning was rampant and mostly successful until relatively recently. I posit it plays a much larger part than genetics in the evidence for lower left-handedness rates at the end of the Victorian era. I am in fact somewhat surprised that non-social causes are considered quite so strongly in the report.
A sample consisting of only factory workers seems inherently biased. This was well before the days of equal opportunity employment and if the postulate "left-handers had visible trouble with operating large and heavy machinery that were almost certainly designed for right-handers" holds true, wouldn't left-handers have been less likely to be working in a factory?