首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
外语
Right and Left-handedness in Humans Why do humans, virtually alone among all animal species, display a distinct left-or righ
Right and Left-handedness in Humans Why do humans, virtually alone among all animal species, display a distinct left-or righ
admin
2013-03-11
40
问题
Right and Left-handedness in Humans
Why do humans, virtually alone among all animal species, display a distinct left-or right-handedness? Not even our closest relatives among the apes possess such decided lateral asymmetry (不对称), as psychologists call it. Yet about 90 percent of every human population that has ever lived appears to have been right-handed. Professor Bryan Turner at Deakin University has studied the research literature on left-handedness and found that handedness goes with sidedness. So nine out of ten people are right-handed and eight are right-footed. He noted that this distinctive asymmetry in the human population is itself systematic. Humans think in categories: black and white, up and down, left and fight. It’s a system of signs that enables us to categorize phenomena that are essentially ambiguous (含糊不清的).
Research has shown that there is genetic or inherited element to handedness. But while left- handedness tends to run in families, neither left nor fight handers will automatically produce off- spring with the same handedness; in fact about 6 percent of children with two fight-handed parents will be left-handed. However, among two left-handed parents, perhaps 40 percent of the children will also be left-handed. With one fight and one left-handed parent, 15 to 20 percent of the offspring will be left-handed. Even among identical twins who have exactly the same genes, one in six pairs will differ in their handedness.
What then makes people left-handed if it is not simply genetic? Other factors must be at work and researchers have turned to the brain for clues. In .the 1860s the French surgeon and anthropologist (人类学家), Dr. Paul Broca, made the remarkable finding that patients who had lost their powers of speech as a result of a stroke (a blood clot in the brain) had paralysis (瘫痪) of the right half of their body. He noted that since the left hemisphere of the brain controls the right half of the body, and vice versa, the brain damage must have been in the brain’s left hemisphere, Psychologists now believe that among right handed people, probably 95 percent have their language centre in the left hemisphere, while 5 percent have right-sided language. Left-handers, however, do not show the reverse pattern but instead a majority also have left hemisphere language.
Dr. Brinkman, a brain researcher at the Australian National University in Canberra, has suggested that evolution of speech went with right-handed preference. According to Brinkman, as the brain evolved, one side became specialized for free control of movement (necessary for producing speech) and along with this evolution came right-hand preference. According to Brinkman, most left-handers have left hemisphere dominance but also some capacity in the right hemisphere. She has observed that if a left-handed person is brain-damaged in the left hemisphere, the recovery of speech is quite often better and this is explained by the fact that left-handers have a more bilateral (双边的) speech function. In her studies of macaque (猕猴) monkeys, Brinkman has noticed that primates (monkeys) seem to learn a hand preference from their mother in the first year of life but this could be one hand or the other. In humans, however, the specialization in function of the two hemispheres results in anatomical (人体的) differences; areas that are involved with the production of speech are usually larger on the left side than on the right. Since monkeys have not acquired the art of speech, one would not expect to see such a variation but Brinkman claims to have discovered a trend in monkeys towards the asymmetry that is evident in the human brain,
Two American researchers, Geschwind and Galaburda, studied the brains of human embryos and discovered that the left-right asymmetry exists before birth. But as the brain develops, a number of things can affect it. Every brain is initially female in its organization and it only becomes a male brain when the male foetus (胎儿) begins to secrete hormones, Geschwind and Galaburda knew that different parts of the brain mature at different rates; the right hemisphere develops first, then the left. Moreover, a girl’s brain develops somewhat faster than that of a boy. So, if something happens to the brain’s development during pregnancy, it is more likely to be affected in a male and the hemisphere more likely to be involved is the left. The brain may become, less lateralized (单侧性的) and this in turn could result in left-handedness and the development of certain superior skills that have their origins in the left hemisphere such as logic, rationality and abstraction. It should be no surprise then that among mathematicians and architects, left-handers tend to be more common and there are more left-handed males than females.
The results of this research may be some consolation to left-handers who have for centuries lived in a world designed to suit right-handed people. However, what is alarming, according to Mr. Charles Moore, a writer and journalist, is the way the word "right" reinforces its own virtue. Subliminally, he says, language tells people to think that anything on the right can be trusted while anything on the left is dangerous or even sinister (险恶的). However, as more research is undertaken on the causes of left handedness, attitudes towards left-handed people are gradually changing for the better. Indeed when the champion tennis player Ivan Lendl was asked what the single thing improve his game, he said he would like to become a left-hander.
If two parents are both left-handed, the possibility that their children will also be left-handed increases.
选项
A、Y
B、N
C、NG
答案
A
解析
转载请注明原文地址:https://kaotiyun.com/show/GKu7777K
0
大学英语四级
相关试题推荐
A、Howtoselectacanoftomatoes.B、Howtopreparenutritiousanddeliciousmeals.C、Howtospendmoneywiselyonfood.D、Howt
Some300metersup,neartheEiffelTower’swind-whippedsummittheworldcomestoscribble.Japanese,Brazilians,Americans—the
Robot.Itisawordthatseemsverymodern.Awordthatcreatesastrongmentalpicture.Apictureofsomethingthatlooksanda
Inadditiontovisibletrade,whichinvolvestheimportandexportofmerchandise,thereisalso【S1】______trade,whichinvolves
A、Thetemperaturemaybehigher.B、Musclecouldgethurt.C、Conditionscouldbemoreserious.D、Thedoctorsneedtimetoarrive.
A、Fifteenminutes.B、Twenty-fiveminutes.C、Thirty-fiveminutes.D、Forty-fiveminutes.C对话中,男士问下一班列车何时离开,女士说上一班车15分钟之前刚离开,每50分钟就
A、Aspeech.B、Amovie.C、Aplay.D、Alecture.C
Theylearn___________(如何处理个人问题)aswellaslearnhowtothink,tomakedecisions,toanalyzeandevaluate,andtocommunicateeff
Forthispart,youareallowed30minutestowriteashortessayentitledHavingaBoyfriendorGirlfriendonCampus.Youshould
A、Newly-launchedproducts.B、Drugusers.C、Surveyresults.D、Publicfigures.C女士问男士昨天进行的关于毒品使用与健康的调查的数据是否可靠,男士作出了回答,可知C为答案。
随机试题
钢板下料应采用()
设随机变量X的分布律为则E(X)=___________.
成年男性红细胞计数高于女性的原因与下列哪项因素关系最密切
A.多经血道转移B.多经淋巴道转移C.多由种植性转移D.以上三者均可E.不发生转移子宫颈原位癌
一般手术区皮肤的准备(备皮),一般是提前()。
某5×30m在用预应力混凝土连续箱形梁桥,横断面为单箱单室构造,见下图。试验前经检查三个中跨的结构状况基本相同。现选其中两跨进行静、动载试验,试完成以下相关试验设计和相关操作。关于动载试验,以下表述正确的有()。
政策性银行与商业性金融机构的最显著不同在于()。
根据我国现行宪法规定,在社会主义初级阶段,我国实行的分配制度是按劳分配与按需分配相结合。
行政管理的基础是国家行政权力。( )
Yourweightaffectshowlongyoulive—butit’sextremelycomplicatedA)Weoftenthinkaboutweightlossintheshortterm,h
最新回复
(
0
)