国产一二三四五路线-国产一级高清-国产一级毛片卡-国产一级毛片一区二区三区-中文字幕在线视频播放-中文字幕在线高清

您好!歡迎訪問忙推網(wǎng)! 字典 詞典 詩詞
首頁 教育 短篇英語散文:How come our fingers are different sizes&nb

短篇英語散文:How come our fingers are different sizes&nb

時間:2024-07-19 22:26:46 來源:網(wǎng)絡(luò) 作者:mrcsb 人氣:9699
【導(dǎo)讀】:How come our fingers are different sizes and lengths?我們的手指為什么會大小長短不一How come our fingers are different sizes and lengths? asks Alec Pemara, a stu...

How come our fingers are different sizes and lengths?我們的手指為什么會大小長短不一

How come our fingers are different sizes and lengths? asks Alec Pemara, a student in Manhasset, NY.

Hands and fingers aren’t unique to human beings; other primates have them, too. Take a look at gorilla or chimp’s hands and you’ll see a set of four fingers, varying in length from index to pinky, along with a real thumb. (While other animals, such as raccoons, have paws that resemble hands, official "hands" belong only to primates.)

Hands are useful for grasping—hanging onto a tree limb (or hanging onto a ladder), picking berries (or picking up groceries), throwing a clod of dirt (or throwing a baseball). If our fingers were the same length, our hands wouldn’t be such flexible tools. When we hold a spherical object like an orange in the palm of our hand, the fingers actually curve around evenly, giving us a firm grip. Tapering fingers (and strong thumbs) allowed early humans to use specially-shaped stones to smash, scrape and cut other objects. (A long pinky finger would be more likely to get caught and squashed itself.) Besides precision grips, our different-length fingers also provide a balanced support for crawling or leaning on our hands.

Among different species of primates—from baboons to monkeys--fingers and thumbs vary in shape and length. Long, thin fingers are best for tree-swinging. Chimpanzees, who themselves make and use simple tools like termite-catchers, have hands that most resemble ours.

Most primates, from gorillas, orangutans, and chimpanzees to Old World monkeys, have "opposable" thumbs that can bend outward at up to a 90-degree angle from the other fingers. The most developed opposable thumbs are especially handy for holding small objects between thumb and index finger.

Thumbs have only one middle joint, rather than the two joints found on the four regular fingers. The four longer fingers can curl further around an object, while powerful muscles allow the thumb to "lock in" the grip, vise-like. Human opposable thumbs are, compared to those of other primates, bigger and stronger. A chimp can pick up a peanut from the ground, but can’t open a tightened lid on a jar of peanut butter. Our own powerful thumbs seem to have evolved in tandem with our tool-making skills.

Among individuals in each primate species, finger and thumbs vary, too. Compare your hands to those of your friends, and you’ll see subtle and not-so-subtle differences. Boys and men often have longer ring than index fingers. Girls and women tend to have similar-length ring and index fingers, or shorter ring fingers. Scientists say the differences are due to the influence of the hormones estrogen and testosterone in the womb.

One study found that male physicists, chemists, and mathematicians had ring and index fingers about equal in length, while male economists and social scientists had longer ring fingers. Another study found that men with substantially shorter index than ring fingers tended to be more physically aggressive than others.

文章標簽:
    英語閱讀,英語美文,英語學(xué)習(xí),英語
相關(guān)推薦

版權(quán)聲明:

1、本文系會員投稿或轉(zhuǎn)載自網(wǎng)絡(luò),版權(quán)歸原作者所有,旨在傳遞信息,不代表看本站的觀點和立場;

2、本站僅提供信息展示,不承擔(dān)相關(guān)法律責(zé)任;

3、若侵犯您的版權(quán)或隱私,請聯(lián)系本站管理員刪除。

字典 詞典 成語 古詩 造句 英語
主站蜘蛛池模板: 美女张开腿黄网站免费国产 | 美国一级毛片片aa成人 | 女人张开腿让男人捅爽 | 国产美女毛片 | 国产成人国产在线观看入口 | 曰本黄页| 久久香蕉国产线看免费 | 国产在线精品一区二区不卡 | 特级毛片aaaa免费观看 | 九九看片 | 狠狠88综合久久久久综合网 | 99国产视频| 欧美很黄视频在线观看 | 成人看的一级毛片 | 图片区偷拍区小说区 | 中文字幕免费在线视频 | 亚州在线视频 | 国产成人精品三级91在线影院 | 美女视频黄视大全视频免费网址 | 国产99视频精品免费视频7 | 成人看片黄a在线看 | 天堂影院jav成人天堂免费观看 | 亚洲国产高清一区二区三区 | 亚洲第一页视频 | 九九精品免费观看在线 | 波多野结衣一区二区 三区 波多野结衣一区二区三区88 | 精品视频一区二区三区 | 中文字幕日韩一区二区不卡 | 亚洲精品久久久久综合中文字幕 | 色综合精品 | 久久www视频 | 欧美成人免费看片一区 | 国产一进一出视频网站 | 九九久久精品 | 99久久精品免费精品国产 | 日本www在线播放 | 国产大学生自拍 | 在线播放第一页 | 乱码在线中文字幕加勒比 | 免费一级毛片私人影院a行 免费一级毛片无毒不卡 | 亚洲精品久久九九精品 |