Hair and evolution 毛发和进化论
<p>随身英语<span word="Hair">Hair</span> <span word="and">and</span> <span word="evolution">evolution</span> 毛发和进化论</p><p><span word="Play">Play</span> <span word="audio">audio</span> <span word="file">file</span>为什么进化后的人类毛发稀疏？而和我们人类最近似的动物王国里的亲戚则仍全身匹着毛发？在物种进化过程中，毛发稀疏的人类是如何确保自己能成功生存下来？本期《随身英语》谈论毛发和人类进化的关系。</p><p>课文内容 词汇: <span word="Evolution">Evolution</span> 进化</p><p><span word="Compared">Compared</span> <span word="to">to</span> <span word="other">other</span> <span word="large">large</span> <span word="mammals">mammals</span> <span word="on">on</span> <span word="Earth">Earth</span>, <span word="we">we</span> <span word="humans">humans</span> <span word="have">have</span> <span word="relatively">relatively</span> <span word="little">little</span> <span word="hair">hair</span>. <span word="This">This</span> <span word="obvious">obvious</span> <span word="fact">fact</span> <span word="is">is</span> <span word="not">not</span> <span word="so">so</span> <span word="strange">strange</span> <span word="until">until</span> <span word="we">we</span> <span word="look">look</span> <span word="at">at</span> <span word="our">our</span> <span word="closest">closest</span> <span word="living">living</span> <span word="relatives">relatives</span> <span word="in">in</span> <span word="the">the</span> <span word="animal">animal</span> <span word="kingdom">kingdom</span> – <span word="chimpanzees">chimpanzees</span> <span word="and">and</span> <span word="other">other</span> <span word="great">great</span> <span word="apes">apes</span>. <span word="Why">Why</span>, <span word="might">might</span> <span word="we">we</span> <span word="ask">ask</span>, <span word="have">have</span> <span word="we">we</span> <span word="evolved">evolved</span> <span word="to">to</span> <span word="be">be</span> <span word="almost">almost</span> <span word="hairless">hairless</span> <span word="when">when</span> <span word="all">all</span> <span word="other">other</span> <span word="primates">primates</span> <span word="are">are</span> <span word="still">still</span> <span word="covered">covered</span> <span word="in">in</span> <span word="fur">fur</span>? <span word="In">In</span> <span word="fact">fact</span>, <span word="bizarre">bizarre</span> <span word="as">as</span> <span word="it">it</span> <span word="may">may</span> <span word="seem">seem</span>, <span word="our">our</span> <span word="lack">lack</span> <span word="of">of</span> <span word="hair">hair</span> <span word="has">has</span> <span word="been">been</span> <span word="the">the</span> <span word="key">key</span> <span word="to">to</span> <span word="our">our</span> <span word="evolutionary">evolutionary</span> <span word="success">success</span> <span word="as">as</span> <span word="a">a</span> <span word="species">species</span>.</p><p><span word="The">The</span> <span word="question">question</span> <span word="why">why</span> <span word="our">our</span> <span word="earliest">earliest</span> <span word="ancestors">ancestors</span> <span word="lost">lost</span> <span word="their">their</span> <span word="hair">hair</span> <span word="when">when</span> <span word="fur">fur</span> <span word="would">would</span> <span word="have">have</span> <span word="been">been</span> <span word="beneficial">beneficial</span> <span word="to">to</span> <span word="them">them</span> – <span word="for">for</span> <span word="keeping">keeping</span> <span word="warm">warm</span> <span word="on">on</span> <span word="cold">cold</span> <span word="nights">nights</span>, <span word="for">for</span> <span word="example">example</span> – <span word="was">was</span> <span word="pondered">pondered</span> <span word="by">by</span> <span word="Charles">Charles</span> <span word="Darwin">Darwin</span>, <span word="the">the</span> <span word="famous">famous</span> <span word="evolutionist">evolutionist</span>: "<span word="No">No</span> <span word="one">one</span> <span word="supposes">supposes</span> <span word="that">that</span> <span word="the">the</span> <span word="nakedness">nakedness</span> <span word="of">of</span> <span word="the">the</span> <span word="skin">skin</span> <span word="is">is</span> <span word="any">any</span> <span word="direct">direct</span> <span word="advantage">advantage</span> <span word="to">to</span> <span word="man">man</span>." <span word="He">He</span> <span word="concluded">concluded</span> <span word="that">that</span> <span word="the">the</span> <span word="reason">reason</span> <span word="hominins">hominins</span> <span word="lost">lost</span> <span word="their">their</span> <span word="hair">hair</span> <span word="was">was</span> <span word="sexual">sexual</span> <span word="selection">selection</span>. <span word="In">In</span> <span word="other">other</span> <span word="words">words</span>, <span word="we">we</span> <span word="prefer">prefer</span> <span word="our">our</span> <span word="partners">partners</span> <span word="to">to</span> <span word="have">have</span> <span word="little">little</span> <span word="hair">hair</span>. <span word="But">But</span> <span word="what">what</span> <span word="caused">caused</span> <span word="our">our</span> <span word="ancestors">ancestors</span> <span word="to">to</span> <span word="start">start</span> <span word="losing">losing</span> <span word="their">their</span> <span word="hair">hair</span> <span word="before">before</span> <span word="this">this</span> <span word="preference">preference</span> <span word="set">set</span> <span word="in">in</span>?</p><p><span word="The">The</span> <span word="most">most</span> <span word="likely">likely</span> <span word="hypothesis">hypothesis</span> <span word="to">to</span> <span word="explain">explain</span> <span word="the">the</span> <span word="loss">loss</span> <span word="of">of</span> <span word="hair">hair</span> <span word="is">is</span> <span word="that">that</span> <span word="it">it</span> <span word="became">became</span> <span word="necessary">necessary</span> <span word="when">when</span> <span word="early">early</span> <span word="hominids">hominids</span> <span word="moved">moved</span> <span word="to">to</span> <span word="a">a</span> <span word="more">more</span> <span word="open">open</span> <span word="savannah">savannah</span> <span word="habitat">habitat</span> <span word="around">around</span> 2 <span word="to">to</span> 3 <span word="million">million</span> <span word="years">years</span> <span word="ago">ago</span>, <span word="when">when</span> <span word="they">they</span> <span word="started">started</span> <span word="to">to</span> <span word="hunt">hunt</span> <span word="big">big</span> <span word="game">game</span>.<span word="Hunting">Hunting</span> <span word="in">in</span> <span word="open">open</span> <span word="savannah">savannah</span> <span word="meant">meant</span> <span word="being">being</span> <span word="exposed">exposed</span> <span word="to">to</span> <span word="the">the</span> <span word="strong">strong</span> <span word="heat">heat</span> <span word="of">of</span> <span word="the">the</span> <span word="sun">sun</span> <span word="for">for</span> <span word="several">several</span> <span word="hours">hours</span> <span word="in">in</span> <span word="the">the</span> <span word="day">day</span> <span word="and">and</span> <span word="being">being</span> <span word="in">in</span> <span word="danger">danger</span> <span word="of">of</span> <span word="overheating">overheating</span>. <span word="Being">Being</span> <span word="covered">covered</span> <span word="in">in</span> <span word="hair">hair</span> <span word="prevented">prevented</span> <span word="our">our</span> <span word="ancestors">ancestors</span> <span word="from">from</span> <span word="losing">losing</span> <span word="heat">heat</span> <span word="fast">fast</span> <span word="enough">enough</span>. <span word="So">So</span>, <span word="as">as</span> <span word="Peter">Peter</span> <span word="Wheeler">Wheeler</span>, <span word="of">of</span> <span word="Liverpool">Liverpool</span> <span word="John">John</span> <span word="Moores">Moores</span> <span word="University">University</span> <span word="in">in</span> <span word="the">the</span> <span word="UK">UK</span>, <span word="explained">explained</span>, <span word="losing">losing</span> <span word="hair">hair</span> <span word="allowed">allowed</span> <span word="them">them</span> <span word="to">to</span> <span word="develop">develop</span> <span word="the">the</span> <span word="ability">ability</span> <span word="to">to</span> <span word="sweat">sweat</span> <span word="and">and</span> <span word="therefore">therefore</span> <span word="to">to</span> <span word="cool">cool</span> <span word="down">down</span>. <span word="Early">Early</span> <span word="humans">humans</span> <span word="could">could</span>, <span word="as">as</span> <span word="a">a</span> <span word="consequence">consequence</span>, <span word="be">be</span> <span word="out">out</span> <span word="at">at</span> <span word="midday">midday</span> <span word="hunting">hunting</span> <span word="and">and</span> <span word="foraging">foraging</span>. "<span word="It">It</span> <span word="would">would</span> <span word="be">be</span> [<span word="an">an</span>] <span word="enormous">enormous</span> <span word="advantage">advantage</span> <span word="to">to</span> <span word="be">be</span> <span word="able">able</span> <span word="to">to</span> <span word="spend">spend</span> <span word="the">the</span> <span word="entire">entire</span> <span word="midday">midday</span> <span word="foraging">foraging</span>, <span word="finding">finding</span> <span word="mates">mates</span> <span word="or">or</span> <span word="fighting">fighting</span> <span word="enemies">enemies</span>", <span word="Tam">Tam</span>á<span word="s">s</span> <span word="D">D</span>á<span word="vid">vid</span>-<span word="Barrett">Barrett</span> <span word="of">of</span> <span word="Oxford">Oxford</span> <span word="University">University</span> <span word="says">says</span>. "<span word="Sweating">Sweating</span> <span word="allows">allows</span> <span word="that">that</span>, <span word="and">and</span> <span word="for">for</span> <span word="sweat">sweat</span> <span word="to">to</span> <span word="be">be</span> <span word="efficient">efficient</span> <span word="you">you</span> <span word="need">need</span> <span word="to">to</span> <span word="be">be</span> <span word="mostly">mostly</span> <span word="hairless">hairless</span>". <span word="The">The</span> <span word="meat">meat</span> <span word="from">from</span> <span word="hunting">hunting</span> <span word="animals">animals</span> <span word="gave">gave</span> <span word="early">early</span> <span word="humans">humans</span> <span word="the">the</span> <span word="energy">energy</span> <span word="to">to</span> <span word="fuel">fuel</span> <span word="their">their</span> <span word="growing">growing</span> <span word="brain">brain</span>.</p>
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