I was flipping through the paper and noticed an opinion piece by linguist and science writer Rik Smits, “Lefties aren’t special after all”:
Few truly insignificant traits receive as much attention as left-handedness. In just the last couple of generations, an orientation once associated with menace has become associated with leadership, creativity, even athletic prowess. Presidents Gerald R. Ford, George Bush, Bill Clinton and Barack Obama were born left-handed (as was Ronald Reagan, though he learned to write with his right hand). Folklore has it that southpaws are unusually common in art and architecture schools. Left-handed athletes like Tim Tebow and Randy Johnson are celebrated.
Sounds interesting so far. Then we get several paragraphs of history of how people got things wrong (authoritarians of past generations who forced lefties to use their right hands, silly “blank slate” ideologues, etc.).
What about the science? Smits writes:
Left-handers have been redefined as creative, broad-minded, natural leaders. Meanwhile, other studies continue to identify all sorts of negative associations with left-handers — clumsiness, propensity to die prematurely, higher breast cancer rates and greater vulnerability to suicide.
After reviewing hundreds of such studies for a book on left-handers, I [Smits] found that the evidence of positive qualities associated with left-handedness was anecdotal at best, while the scores of studies associating left-handedness with all manner of afflictions were generally too unreliable to have any practical consequence.
I’d have to see Smits’s book to judge (and, before you get on my case for commenting on a book that I haven’t read, please reflect that Smits chose to publish his article in the Times, and I think it’s expected that many people will write a newspaper article without reading the corresponding book. Certainly, when I wrote op-eds about Red State Blue State, I wanted these to stand on their own for the benefit of the vast majority of newspaper readers who were not reading the book), but I’m skeptical of his skepticism. The studies I’ve seen of handedness do have potential problems, so I wouldn’t object to labeling as “speculative” such claims such as “mathematicians are more likely to be left-handed” or “left-handers live shorter lives than right-handers.” At the same time, such claims are not scientifically implausible, and they do seem supported to some extent by the data.
I have not looked at the research on handedness recently, so I’m not sure whether Smits’s skepticism reflects new information or whether it is just a statement that the claimed findings about left-handers have not been proved. If the latter, I think it would be better to say that it’s not clear to what extent left-handers are different from the majority, rather than to say with such certainty that “lefties aren’t special at all.”
P.S. I’m right-handed. I don’t have any personal stake in all this; it’s a topic I got interested in awhile ago when Seth and I taught our class on left-handedness. At the time we recognized the weakness of the studies on the topic, but we also recognized weaknesses in sweeping arguments that attempted to dismiss the findings by arguing for selection effects etc. My impression at the time was that there was some evidence of interesting and important systematic differences between lefties and righties, but that it was also possible we were seeing nothing more than a bunch of statistical artifacts. My conclusion was that skepticism was warranted but it would be going too far to be certain that nothing was going on.
Although I haven’t seen any proper research on this, the general wisdom in cricket is that it is easier for a batsman to face a bowler of the opposite handedness to him (plus bowlers have difficulty in adjusting to bowling to batsmen of alternating handedness). This led to a proliferation of left handed batsmen in international sides to face the predominantly right handed bowlers. But now left handed bowlers have an edge, so they are increasing in prevalence. There is a delay in reaching equilibrium at an international level as the same processes are playing out in lower levels of cricket and it takes a period of superior performance to earn a place in the national team.
I expect the equilibrium state would have a higher prevalence of left handed players than their prevalence in the population would suggest, but this is not due to any inherent superiority or trait other than the handedness in itself.
Smits book is far-ranging and is really about symmetry and the lack of symmetry. For example, he claims that up vs. down causes far less difficulty than right vs. left. This is why young kids learning English script have no difficulty distinguishing the letter “p” from “b” but have problems with “b” vs. “d.” Further, he looks at Arabic and Chinese scripts which also favor righties (e.g., the problem of smudging as the hand moves) even though, opposite to English, they go from right to left. His explanations for how the strokes are made are compelling. In addition, he has chapters on the non-symmetrical layout of paintings.
Smits dismisses the allegation by Coren and Halpern that lefthanded baseball players die younger than righthanded baseball players. The dismissal is based on the statistical study by E.K. Wood (Nature, Vol. 335, 15 September 1988). Although not stated by Smits, Wood used the (nonparametric) Kolmogorov–Smirnov test for maximum difference applied to about 4000 players and concluded, “no statistically significant difference between mortalities of left-handed and right-handed players.” Coren and Halpern may have used the two-sample t test which is more sensitive but suffers from the assumption that the only difference is due to difference in means.
In passing, note that according to http://www.livestrong.com/article/269357-left-handed-rules-for-polo/, “Just as in equestrian polo, bicycle polo players are forbidden from playing left-handed, according to the official rules of the International Bicycle Polo Federation.”
You might like Chris McManus’ “Right Hand, Left Hand” (http://books.google.com/books?id=20oza63ZuG4C) about all sorts of (mostly cultural and biological) aspects of about left-right asymmetry, including, of course, handedness. There’s a neat discussion about genetics: it’s thought that there are two genes for handedness, each of which has two alleles, one of which promotes right handedness and the other of which promotes random handedness. The book is full of fascinating things. It’s not really relevant for this thread, but for example, about 1/10000 people are ‘flipped’ left-to-right, with their hearts on the right side, livers on the left, etc. (You can try to guess: are 90% of them left handed? Or 10%?) I teach a ‘biophysics for non-science-students’ course that asks questions exploring this and its underlying causes as a fun example on the first day of the term.
There are good physiological data showing that lefties’ brains are organized differently. It seems like a safe bet that every time brains are significantly different, interesting and important systematic differences in behavioral traits will result.
What about studies on dominance and cross-dominance? These apply not only to handedness, but also to dominant eyes, legs, etc. I’ve seen some work done, but most of it is from self-reported stats which should lead to major issues, particularly for cross-dominant folks.
It’s possible that the left/right difference in life expectancy will have disappeared by now, since manufacturers started mounting car-radio controls on the steering-wheel. Still to come — differences in time spent at the drive-through automatic teller machine. :D
I fully agree with Andrews criticism that “I think it would be better to say that it’s not clear to what extent left-handers are different from the majority, rather than to say with such certainty that “lefties aren’t special at all”. It may sound as a lame excuse, but I did not make the headline (but I wasn’t really against it, as it was bound to stir up something).
Certainly lefties are different, at any rate they have a somewhat different brain architecture — a bit less lateralized, like women’s brains, it was long believed for quite sound reasons. Recent work points to it that the differences might be bigger than was thought (interesting MRI-work by Casasanto 2010, for instance). My problem with all those associations is basically that it seems like ANYTHING will correllate with lefthandedness. A (slight) overrepresentation has been reported in groups defined by virtually any criterion, be it positive (creative! highly gifted! leadership!) or negative (any disease, trauma or affliction you can thingk of, being in jail or hospital and so on an so forth). At the same time, lefthanders are consistently so inconspicuous that even their close relatives fail to notice their deviance from the norm. When queried about the handedness of close family and friends, it turned out that people gave appr. 30% wrong answers. It seems to me there must be a rat somewhere, but it’s so elusive I cannot even really smell it.
Rik:
Thanks for the reply and the further details. As a statistician, I’m particularly sensitive to claims of the form, “not-statistically-proven = zero.” As a linguist, you might very well have an opposite sensitivity to overblown claims that have not been proven.
Here’s my recent article about the continuing discrimination against lefthanded catchers in baseball:
http://takimag.com/article/the_forgotten_leftists_steve_sailer/print#axzz1uAx0ayL6
I also discuss why lefthanders are not an identity politics group of any clout.
Steve:
I suspect that one reason left-handers are not an identity politics group is that (adult) left-handers have not been subject to discrimination, at least not recently.
My favourite study is:
http://www.ncbi.nlm.nih.gov/pubmed/9141638
The prevalence of LH was lower in ever-married subjects compared with never-married subjects … The risk of LH was elevated in men diagnosed with fractures as compared with all other male patients…The odds ratio of LH was significantly lower in women with breast cancer…
All these associations hold up in meta-analyses, IIRC.