Left, right, left, wrong
I’ve never thought of myself as part of a minority, but flicking through a scientific journal this week it dawned on me that I am. I’m talking about my place among the vilified 10 per cent of people who favour the use of their left hands and feet, rather than their right. Reading an article on the multitudinous theories about why people develop such preferences, I was reminded of some of the routine humiliations a southpaw must suffer.
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At primary school, for example, my left-handedness singled me out for unwanted attention from authorities. When I was six or seven, I distinctly remember a teacher encouraging me (forcing, that is) to write with my right hand, like all the other kids. I tried for a while, but clearly failed, and my handwriting never recovered.
Another blow came in high school when I started to learn Italian. “Shocked” hardly does justice to my feelings when the teacher, a man whose protuberant moustache was bettered only by his belly, explained that the Italian word for left is sinistra, as in sinister. If I’d learned French, gauche would have been an equally unpleasant alternative.
Given these everyday humiliations and the countless other obstacles a left-hander must overcome - scissors, golf clubs, cutlery - it is no surprise to find that we suffer emotionally and physically as a result.
Studies show that left-handers are more prone to a host of different injuries, such as joint pain or finger damage, for example. A Canadian study also found that left-handed college students were significantly more likely than right-handers to have had a motor vehicle accident in the preceding two years.
Back in 1991, researchers Stanley Coren and Diane Halpern published a paper that appeared to seal the fate of left-handers. In the Psychological Bulletin, they reported that “sinistrals” had a 1 to 2 per cent higher risk of dying in any given year, beyond the age of 33. Overall, according to their studies, left-handers die an average of eight years earlier than right-handers.
Those results offered a possible explanation for the well-recorded fact that the proportion of the population who are left-handed decreases with age. But, thankfully for us lefties, more recent studies have proffered an alternative reason.
For example, in 2000, Olga Basso and other researchers studied more than 100 Danish twins born between 1900 and 1910, and found that left-handers died no earlier than right-handers. The reason fewer old people were left-handed, they suggested, was because more of them had been badgered into switching to right-handedness in their youth.
Still, we’re left with the question of why it is that something like one in 10 people favours their left hand, while the rest use their right more often. There seems to be no short answer to that.
One element is genetic. An article in Scientific American Mind this month points out that two right-handed people have only a 9.5 per cent chance of having a left-handed child, while the chance is 19.5 per cent for a mixed-handed couple and 26 per cent for a pair of left-handers. Then again, one in five sets of genetically identical twins favour different hands, suggesting other factors are at play.
Another possibility is that being left-handed is somehow a result of brain damage. Some studies have found a link between trauma at birth, or lack of oxygen at birth, and being left-handed. Others have pointed out that left-handers are more likely to suffer learning disorders and epilepsy. But researchers have also shown that handedness is apparent before birth: some fetuses prefer to suck on their left thumb, rather than their right.
One thing that is pretty clear is that handedness is associated with the differing functions of the brain’s two hemispheres, and more specifically language. Among most people, language is processed more intensely in the left hemisphere of the brain - the side that operates the right side of the body. This fact suggests to some scientists that language might have played a strong part in driving the dominance of right-handedness.
Interestingly, among a few left-handers, the language processing is more dominant on the right side of the brain, or is handled by both sides equally. I’ve seen it suggested that this might play a part in the much-vaunted creativity of lefties, and could even be an explanation for why left-handedness has survived throughout human evolution.
Whether that’s the case, there do seem to be a lot of creative left-handers. The standard list includes Raphael, Leonardo da Vinci, Lewis Carroll, Jean Genet and C.P.E. Bach, for example.
Maybe their creativity is a result of the way their brains were organised in the first place, or perhaps it is an effect of their having to get by in a right-handed world. Regardless, it’s a sad fact that for most of us southpaws, the great-artist club is one minority to which we definitely do not belong.
左撇子的是与非
我从来没觉得自己属于少数人之列，但上周翻了一本科学杂志后，我才逐渐意识到。我这里所说的是少数因惯用左手、左脚而被鄙视的人，他们约占总人口的10%。有一篇文章介绍了人们为何会形成这种倾向的各种理论，这令我想到作为一个左撇子在生活中必然经受的一些羞辱。
例如，在上小学时，我因为左撇子而受到老师的关注。我还清楚地记得在我六、七岁时，一位老师鼓励我（实际上是强迫我）像所有其他孩子那样用右手写字。我尝试了一段时间，但显然没有成功，而从此我的字就再也没能写好过。
另一次打击是在中学时，我刚开始学意大利语。当那位大胡子老师（他那簇引人注目的胡子只有便便大腹堪与之媲美）解释道，“左”在意大利语中为sinistra（罪恶之意）时，我呆住了，“震惊”一词几乎不足以形容我当时的感受。如果那时我学法语，那么gauche（法语左手，意为笨拙）也同样会是一次不快的经历。
鉴于这些日常生活中的羞辱，以及左撇子必须要克服的其它无数障碍――剪刀、高尔夫球杆、餐具――无怪乎人们发现，我们在情绪上和身体上都受到伤害。
研究表明，左撇子更易遭受各种各样的伤害，如关节痛或手指损伤。加拿大的一项研究也发现，在过去两年内，左撇子大学生的机动车事故率明显高于右撇子学生。
研究员斯坦利?科伦(Stanley Coren)和戴安娜?哈尔彭(Diane Halpern)1991年发表的一篇论文，似乎决定了左撇子的命运。这篇刊载于《心理学公报》(Psychological Bulletin)的文章指出，在任何一年，33岁以上的左撇子的死亡率都要比右撇子高1%至2%；总体上，左撇子的平均寿命要短8年。
上述结果可能为左撇子人数随年龄增大而减少的有力事实提供了解释。但让我们这些左撇子们心存感激的是，一些最新研究提供了另一种解释。
例如在2000年，奥尔加?巴索(Olga Basso)和其他研究人员对丹麦100多位出生于1900至1910年间的双胞胎进行了研究，他们发现左撇子的寿命并不比右撇子短。他们认为，老年左撇子的数量之所以减少，可能是因为其中更多人在年轻时被迫改用右手。
但还有一个问题没有解决：为什么总有十分之一的人喜欢用左手，而其他人则更经常用右手呢？答案似乎一言难尽。
其中一个因素是遗传。本月，一篇发表于《科学美国人》(Scientific American Mind)的文章指出，一对右撇子夫妇只有9.5%的几率生出一个左撇子孩子；如一方为左撇子，则几率为19.5%；如双方均为左撇子，则几率为26%。不过即使在同卵双胞胎中，也有五分之一用手习惯不同，这说明还有其它因素在起作用。
另一种可能性是：左撇子的形成与大脑受损有关。一些研究发现，左撇子与分娩时受到外伤或缺氧有关。也有研究指出，左撇子更可能遇到学习障碍或患上癫痫症。但研究人员也发现，用手习惯在出生前就十分明显：一些胎儿更喜欢吮吸左手的拇指，而非右手。
然而有一点非常明确，即用手习惯与大脑两个半球的不同功能有关，特别是语言。对多数人来讲，语言处理主要集中在支配身体右半部分的左半脑。这一事实使得一些科学家认为，语言可能为推动右撇子的主导性起到了重要作用。
有趣的是，一些左撇子的语言处理功能更多集中在右半脑，或左右半脑平均分配。我曾见到有人认为，这可能是促成左撇子创造力的原因之一，但这种创造力被严重夸大了；甚至有人以此解释，这可能是左撇子在人类进化过程中幸存下来的原因。
不管这是不是原因所在，生活中似乎确有很多富于创造力的左撇子。公认的名单包括拉斐尔(Raphael)、达芬奇(Leonardo da Vinci)、刘易斯?卡洛尔(Lewis Carroll)、让?热内(Jean Genet)以及C?P?E?巴哈(C.P.E. Bach)等。
他们的创造力可能源于大脑最初的组织方式，也可能是不得不在右手世界中奋力挣扎的结果。不管怎样，对于我们大多数左撇子来说，伟大的艺术家只是一个我们不在其列的少数群体，这是一个令人伤心的事实。
