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: 免费一级特黄a | 成人欧美视频 | 国产激情视频在线播放 | 日韩精品a在线视频 | 酒色成人| 91久久国产露脸精品 | 欧美一级va在线视频免费播放 | 国产护士一级毛片高清 | 日韩亚洲成a人片在线观看 日韩亚洲精品不卡在线 | 久久精品最新免费国产成人 | 一色屋精品亚洲香蕉网站 | 成人全黄三级视频在线观看 | 三级视频在线观看 | www久久com| 手机看片高清国产日韩片 | 成人交性视频免费看 | 欧美日韩一区二区三区免费不卡 | 国产黄色激情视频 | 免费欧美一级片 | 日本亚欧乱色视频在线观看 | 久久久这里只有精品加勒比 | 香蕉久久夜色精品国产 | 久久国产精品免费 | 亚洲一区二区三区在线视频 | 99视频在线观看视频一区 | 日本αv| 国产91一区二区在线播放不卡 | 天天躁夜夜躁狠狠躁2024 | 一级国产精品一级国产精品片 | 中文字幕视频在线 | 国产欧美日韩精品高清二区综合区 | 五月色婷婷琪琪综合伊人 | 成人手机视频在线观看 | 国产精品毛片va一区二区三区 | 国产系列 视频二区 | 国产成人亚洲综合 | 中文国产成人精品久久水 | 日韩欧美在线观看视频一区二区 | 亚洲毛片视频 | 大片毛片女女女女女女女 | 国产午夜伦伦伦午夜伦 |