进化添惊喜,左利人丁旺

“我是个左撇子，”以美国总统的身份签署第一份官方文件时，巴拉克・奥巴马这样打趣道。

“适应这种状况吧。”

考虑到左利人群在生活的方方面面似乎都极其不便，这真是一个很好的建议；尽管进化卡片的排列顺序对他们不利――从各种疾病的患病几率到发生事故风险都较常人高。

现在，科学家们却认为，在左利“少数人群”的背后有一些“左一点”的秘密：意外的惊喜元素。

根据法国蒙彼利埃大学的进化科学研究所研究小组的说法，不管是在网球比赛还是匕首械斗中，从左侧进攻经常会使90％的人失去防备。

他们说，左利人士还有一个关键的优点，那就是：平均来看，左利人群比右利人群有着更高的赚钱能力。

不利于左利者生存的情况

研究人员对以往收集的有关左利人群的资料进行了分析，并将研究报告发表在最近一期《英国皇家学会哲学会刊》上。

他们发现了不胜枚举的关联的进化代价，比如左利者患上精神分裂症、癫痫症、孤僻症和学习障碍等的几率较高。

研究小组称，左撇子――大约十人中有一人――在发生严重事故的比率上同样会较高，这可能是由于我们这个机械化的现代社会所配置的工具主要是为右利者准备的。

研究者称男性左利者可能还会在繁衍后代方面处于不利地位，因为他们的平均身材较右利者矮，这对于女性的吸引力相对较弱。

走出“利右”阴霾

鉴于这些不利左利者的进化痕迹，左利“少数派”是如何逃离灭绝宿命的呢？

研究者称，一项关键性的线索可能是――在一对一的体育比赛上左利运动员（总能）战胜右利运动员。比如网坛的约翰・麦肯罗、玛蒂娜・纳芙拉蒂诺娃、吉米・康纳斯和拉菲尔・纳达尔（现时世界排名第一）都是左撇子。

研究报告作者之一的夏洛特・福瑞在一项关于暴力打斗杀人犯的研究中发现了惊人的类似结果。

由于左撇子不常见，“他们的对手会对其打斗方式感到惊异，这会给左撇子提供一定优势，”她补充道。

“在网球比赛、拳击打斗或者任何面对面对抗的体育活动中，都会出现同样的情况。”福瑞接着说。

福瑞研究了（在械斗中）左撇子对诸如刀具和弓箭等传统工具的使用。

“在枪支使用上也可能会出现同样情形，因为用右手或左手开枪，子弹飞行的方向会有所不同，”她说道。

而且，“由于左利者在打斗中有战略优势，经过世代的自然选择后，左利人群越来越常见，” 福瑞说――尽管进化上的劣势抵消了这些优势。

她说，打斗的胜利者“会吸引更多女，因此也更有可能繁衍后代。”

因为通常情况下，生死搏斗都是男人的活动，左利女性并不需要这项致命的惊喜元素。不过，福瑞表示，左利特征从母亲遗传给儿子最为普遍。

“所以，对于女性来说，通过儿子的胜利还是可以获得间接的优势呢，”她说。

左利的好处

占人类10％的左利人群除了战斗能力强外，还有好多方面要感谢上天的恩赐呢。

研究小组表示，打个比方说，左利人群有可能显示出更为出色的左右手协调能力。智商超过131的“神童”也更有可能是左撇子。

研究小组还发现，左利法国人的平均收入高于右利者――在欧洲其他国家也有类似发现。

福瑞说，大家都知道，（良好的）经济状况可以促进生育成功率，即使在发达国家也是如此，（因此）这就造成富人生出左撇子的几率可能更高――从而又会带来更多左撇子。她还说，“在传统社会里，拥有更高的社会经济地位和生育后代的数量是密切相关的。”

“这与自然选择有关，”福瑞补充道，“因为它提高了个体生育孩子的

几率。”

“I’m a lefty,” Barack Obama joked as he signed his first official papers as U.S. President.

“Get used to it.”

Good advice, considering that left-handed people don’t seem to be going anywhere, despite an array[列阵]

of evolutionary cards from diseases to elevated[提高] risk for accidents stacked[堆积] against them.

Now scientists say there may be a slightly

sinister[不祥的] secret behind the survival of the left-

handed minority: the element of surprise.

Whether during a tennis match or a knife fight,

approaching from the left often catches the other 90% of humanity off guard[不警惕], according to a team from the Institute of Evolutionary Sciences at the University of Montpellier, France.

Another key advantage, they say: left-handed men, on average, have greater earning power than their

right-handed counterparts[对手，搭档].

The Case Against Left-handed Survival

The researchers trawled[拖网捕鱼] through previously

collected data on left-handedness for their report, which appears in the latest issue of the journal Philosophical Transactions of the Royal Society B.

They found numerous associated evolutionary costs, such as increased risk of schizophrenia[精神分裂症],

epilepsy[癫痫症], autism[孤独症] and learning disabilities.

Southpaws[左撇子] about one in ten people also face higher rates of serious accidents, probably because our modern, mechanized society is tooled largely for

right-handers, the team said.

Male lefties may also be at a reproductive

disadvantage, because their on-average shorter stature[身高]

is less attractive to females, the researchers say.

From Out of Left Field

Given the evolutionary marks against them, how has the left-handed minority managed to dodge[避开] extinction[灭绝]?

A key clue may be the success of left-handed

athletes over right-handed competitors in one-on-one sports, the researchers say. Among tennis players, for

example, champions such as John McEnroe, Martina Navratilova, Jimmy Connors, Rafael Nadal the world’s current number one are all left-handed.

Study co-author Charlotte Faurie found a close

parallel[平行] in her study of homicides[杀人者] resulting from violent fights.

Because left-handers are less common, “their

opponents will be surprised by the way they fight, and this will provide lefties an advantage,” she added.

“It’s exactly the same in tennis or in boxing or in any sport where there is face-to-face opposition,” Faurie added.

Faurie studied the use of traditional weapons such as knives and arrows.

But “it could be the same way with guns, because the direction of the bullet will also be different when it comes from the right or the left,” she said.

And “because left-handers have a strategic[战略上的]

advantage in fights, left-handers become more frequent generation after generation, through natural selection,” Faurie said though those gains are tempered[缓和] by the evolutionary disadvantages.

Fight winners, she said, also “attract more sex

partners and are therefore more likely to reproduce.”

Since mortal[终有一死的] combat is traditionally a male activity, left-handed females didn’t need this deadly

element of surprise. Yet left-handedness is most

commonly passed from mothers to sons, Faurie noted.

“So for women, there could be an indirect advantage through the success of their sons,” she said.

Left-handed Benefits

The left-handed 10% of humanity has a lot more to be thankful for than just fighting prowess[威力].

The team noted, for example, that lefties are more likely to show better coordination between both hands. And gifted children with IQs higher than 131 are more likely to be left-handed.

The team also found that left-handed French men have a higher average income than right-handers,

mirroring findings from other European countries.

Since economic status is known to promote

reproductive success, even in industrialized countries, those riches may result in higher birth rates for left-handers

and therefore more lefties, Faurie said. And “in traditional

society, having a higher socioeconomic[社会经济学的]

status is strongly correlated[相互联系] to the number of

offspring produced,” she said.

“That’s relevant[有关的] in natural selection,” Faurie added, “because it increases the likelihood one will have a child,” Faurie added.