進化添驚喜，左利人丁旺

“我是個左撇子，”以美國總統(tǒng)的身份簽署第一份官方文件時，巴拉克·奧巴馬這樣打趣道。

“適應這種狀況吧?！?/p>

考慮到左利人群在生活的方方面面似乎都極其不便，這真是一個很好的建議；盡管進化卡片的排列順序對他們不利——從各種疾病的患病幾率到發(fā)生事故風險都較常人高。

現(xiàn)在，科學家們卻認為，在左利“少數(shù)人群”的背后有一些“左一點”的秘密：意外的驚喜元素。

根據(jù)法國蒙彼利埃大學的進化科學研究所研究小組的說法，不管是在網(wǎng)球比賽還是匕首械斗中，從左側進攻經(jīng)常會使90％的人失去防備。

他們說，左利人士還有一個關鍵的優(yōu)點，那就是：平均來看，左利人群比右利人群有著更高的賺錢能力。

不利于左利者生存的情況

研究人員對以往收集的有關左利人群的資料進行了分析，并將研究報告發(fā)表在最近一期《英國皇家學會哲學會刊》上。

他們發(fā)現(xiàn)了不勝枚舉的關聯(lián)的進化代價，比如左利者患上精神分裂癥、癲癇癥、孤僻癥和學習障礙等的幾率較高。

研究小組稱，左撇子——大約十人中有一人——在發(fā)生嚴重事故的比率上同樣會較高，這可能是由于我們這個機械化的現(xiàn)代社會所配置的工具主要是為右利者準備的。

研究者稱男性左利者可能還會在繁衍后代方面處于不利地位，因為他們的平均身材較右利者矮，這對于女性的吸引力相對較弱。

走出“利右”陰霾

鑒于這些不利左利者的進化痕跡，左利“少數(shù)派”是如何逃離滅絕宿命的呢？

研究者稱，一項關鍵性的線索可能是——在一對一的體育比賽上左利運動員（總能）戰(zhàn)勝右利運動員。比如網(wǎng)壇的約翰·麥肯羅、瑪?shù)倌取ぜ{芙拉蒂諾娃、吉米·康納斯和拉菲爾·納達爾（現(xiàn)時世界排名第一）都是左撇子。

研究報告作者之一的夏洛特·福瑞在一項關于暴力打斗殺人犯的研究中發(fā)現(xiàn)了驚人的類似結果。

由于左撇子不常見，“他們的對手會對其打斗方式感到驚異，這會給左撇子提供一定優(yōu)勢，”她補充道。

“在網(wǎng)球比賽、拳擊打斗或者任何面對面對抗的體育活動中，都會出現(xiàn)同樣的情況?！备Ｈ鸾又f。

福瑞研究了（在械斗中）左撇子對諸如刀具和弓箭等傳統(tǒng)工具的使用。

“在槍支使用上也可能會出現(xiàn)同樣情形，因為用右手或左手開槍，子彈飛行的方向會有所不同，”她說道。

而且，“由于左利者在打斗中有戰(zhàn)略優(yōu)勢，經(jīng)過世代的自然選擇后，左利人群越來越常見，” 福瑞說——盡管進化上的劣勢抵消了這些優(yōu)勢。

她說，打斗的勝利者“會吸引更多女性伴侶，因此也更有可能繁衍后代?！?/p>

因為通常情況下，生死搏斗都是男人的活動，左利女性并不需要這項致命的驚喜元素。不過，福瑞表示，左利特征從母親遺傳給兒子最為普遍。

“所以，對于女性來說，通過兒子的勝利還是可以獲得間接的優(yōu)勢呢，”她說。

左利的好處

占人類10％的左利人群除了戰(zhàn)斗能力強外，還有好多方面要感謝上天的恩賜呢。

研究小組表示，打個比方說，左利人群有可能顯示出更為出色的左右手協(xié)調(diào)能力。智商超過131的“神童”也更有可能是左撇子。

研究小組還發(fā)現(xiàn)，左利法國人的平均收入高于右利者——在歐洲其他國家也有類似發(fā)現(xiàn)。

福瑞說，大家都知道，（良好的）經(jīng)濟狀況可以促進生育成功率，即使在發(fā)達國家也是如此，（因此）這就造成富人生出左撇子的幾率可能更高——從而又會帶來更多左撇子。她還說，“在傳統(tǒng)社會里，擁有更高的社會經(jīng)濟地位和生育后代的數(shù)量是密切相關的?！?/p>

“這與自然選擇有關，”福瑞補充道，“因為它提高了個體生育孩子的

幾率?！?/p>

“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[列陣]

of evolutionary cards – from diseases to elevated[提高] risk for accidents – stacked[堆積] 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[對手，搭檔].

The Case Against Left-handed Survival

The researchers trawled[拖網(wǎng)捕魚] 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[精神分裂癥]，

epilepsy[癲癇癥]， autism[孤獨癥] 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[避開] extinction[滅絕]?

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[殺人者] 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[戰(zhàn)略上的]

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

Fight winners， she said， also “attract more sex

partners and are therefore more likely to reproduce.”

Since mortal[終有一死的] 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[社會經(jīng)濟學的]

status is strongly correlated[相互聯(lián)系] to the number of

offspring produced，” she said.

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