挑战动物起源理论 丹麦海绵需氧极少
<p><span word="One">One</span> <span word="of">of</span> <span word="science">science</span>'<span word="s">s</span> <span word="strongest">strongest</span> <span word="dogmas">dogmas</span> <span word="is">is</span> <span word="that">that</span> <span word="complex">complex</span> <span word="life">life</span> <span word="on">on</span> <span word="Earth">Earth</span> <span word="could">could</span> <span word="only">only</span> <span word="evolve">evolve</span> <span word="when">when</span> <span word="oxygen">oxygen</span> <span word="levels">levels</span> <span word="in">in</span> <span word="the">the</span> <span word="atmosphere">atmosphere</span> <span word="rose">rose</span> <span word="to">to</span> <span word="close">close</span> <span word="to">to</span> <span word="modern">modern</span> <span word="levels">levels</span>. <span word="But">But</span> <span word="now">now</span> <span word="studies">studies</span> <span word="of">of</span> <span word="a">a</span> <span word="small">small</span> <span word="sea">sea</span> <span word="sponge">sponge</span> <span word="fished">fished</span> <span word="out">out</span> <span word="of">of</span> <span word="a">a</span> <span word="Danish">Danish</span> <span word="fjord">fjord</span> <span word="shows">shows</span> <span word="that">that</span> <span word="complex">complex</span> <span word="life">life</span> <span word="does">does</span> <span word="not">not</span> <span word="need">need</span> <span word="high">high</span> <span word="levels">levels</span> <span word="of">of</span> <span word="oxygen">oxygen</span> <span word="in">in</span> <span word="order">order</span> <span word="to">to</span> <span word="live">live</span> <span word="and">and</span> <span word="grow">grow</span>.</p><p><span word="The">The</span> <span word="origin">origin</span> <span word="of">of</span> <span word="complex">complex</span> <span word="life">life</span> <span word="is">is</span> <span word="one">one</span> <span word="of">of</span> <span word="science">science</span>'<span word="s">s</span> <span word="greatest">greatest</span> <span word="mysteries">mysteries</span>. <span word="How">How</span> <span word="could">could</span> <span word="the">the</span> <span word="first">first</span> <span word="small">small</span> <span word="primitive">primitive</span> <span word="cells">cells</span> <span word="evolve">evolve</span> <span word="into">into</span> <span word="the">the</span> <span word="diversity">diversity</span> <span word="of">of</span> <span word="advanced">advanced</span> <span word="life">life</span> <span word="forms">forms</span> <span word="that">that</span> <span word="exists">exists</span> <span word="on">on</span> <span word="Earth">Earth</span> <span word="today">today</span>? <span word="The">The</span> <span word="explanation">explanation</span> <span word="in">in</span> <span word="all">all</span> <span word="textbooks">textbooks</span> <span word="is">is</span>: <span word="Oxygen">Oxygen</span>. <span word="Complex">Complex</span> <span word="life">life</span> <span word="evolved">evolved</span> <span word="because">because</span> <span word="the">the</span> <span word="atmospheric">atmospheric</span> <span word="levels">levels</span> <span word="of">of</span> <span word="oxygen">oxygen</span> <span word="began">began</span> <span word="to">to</span> <span word="rise">rise</span> <span word="app">app</span>. 630 -- 635 <span word="million">million</span> <span word="years">years</span> <span word="ago">ago</span>.</p><p><span word="However">However</span> <span word="new">new</span> <span word="studies">studies</span> <span word="of">of</span> <span word="a">a</span> <span word="common">common</span> <span word="sea">sea</span> <span word="sponge">sponge</span> <span word="from">from</span> <span word="Kerteminde">Kerteminde</span> <span word="Fjord">Fjord</span> <span word="in">in</span> <span word="Denmark">Denmark</span> <span word="shows">shows</span> <span word="that">that</span> <span word="this">this</span> <span word="explanation">explanation</span> <span word="needs">needs</span> <span word="to">to</span> <span word="be">be</span> <span word="reconsidered">reconsidered</span>. <span word="The">The</span> <span word="sponge">sponge</span> <span word="studies">studies</span> <span word="show">show</span> <span word="that">that</span> <span word="animals">animals</span> <span word="can">can</span> <span word="live">live</span> <span word="and">and</span> <span word="grow">grow</span> <span word="even">even</span> <span word="with">with</span> <span word="very">very</span> <span word="limited">limited</span> <span word="oxygen">oxygen</span> <span word="supplies">supplies</span>.</p><p><span word="In">In</span> <span word="fact">fact</span> <span word="animals">animals</span> <span word="can">can</span> <span word="live">live</span> <span word="and">and</span> <span word="grow">grow</span> <span word="when">when</span> <span word="the">the</span> <span word="atmosphere">atmosphere</span> <span word="contains">contains</span> <span word="only">only</span> 0.5 <span word="per">per</span> <span word="cent">cent</span> <span word="of">of</span> <span word="the">the</span> <span word="oxygen">oxygen</span> <span word="levels">levels</span> <span word="in">in</span> <span word="today">today</span>'<span word="s">s</span> <span word="atmosphere">atmosphere</span>.</p><p>"<span word="Our">Our</span> <span word="studies">studies</span> <span word="suggest">suggest</span> <span word="that">that</span> <span word="the">the</span> <span word="origin">origin</span> <span word="of">of</span> <span word="animals">animals</span> <span word="was">was</span> <span word="not">not</span> <span word="prevented">prevented</span> <span word="by">by</span> <span word="low">low</span> <span word="oxygen">oxygen</span> <span word="levels">levels</span>," <span word="says">says</span> <span word="Daniel">Daniel</span> <span word="Mills">Mills</span>, <span word="PhD">PhD</span> <span word="at">at</span> <span word="the">the</span> <span word="Nordic">Nordic</span> <span word="Center">Center</span> <span word="for">for</span> <span word="Earth">Earth</span> <span word="Evolution">Evolution</span> <span word="at">at</span> <span word="the">the</span> <span word="University">University</span> <span word="of">of</span> <span word="Southern">Southern</span> <span word="Denmark">Denmark</span>.</p><p><span word="Together">Together</span> <span word="with">with</span> <span word="Lewis">Lewis</span> <span word="M">M</span>. <span word="Ward">Ward</span> <span word="from">from</span> <span word="the">the</span> <span word="California">California</span> <span word="Institute">Institute</span> <span word="of">of</span> <span word="Technology">Technology</span> <span word="he">he</span> <span word="is">is</span> <span word="the">the</span> <span word="lead">lead</span> <span word="author">author</span> <span word="of">of</span> <span word="a">a</span> <span word="research">research</span> <span word="paper">paper</span> <span word="about">about</span> <span word="the">the</span> <span word="work">work</span> <span word="in">in</span> <span word="the">the</span> <span word="journal">journal</span> <span word="PNAS">PNAS</span>.</p><p><span word="A">A</span> <span word="little">little</span> <span word="over">over</span> <span word="half">half</span> <span word="a">a</span> <span word="billion">billion</span> <span word="years">years</span> <span word="ago">ago</span>, <span word="the">the</span> <span word="first">first</span> <span word="forms">forms</span> <span word="of">of</span> <span word="complex">complex</span> <span word="life">life</span> -- <span word="animals">animals</span> -- <span word="evolved">evolved</span> <span word="on">on</span> <span word="Earth">Earth</span>. <span word="Billions">Billions</span> <span word="of">of</span> <span word="years">years</span> <span word="before">before</span> <span word="that">that</span> <span word="life">life</span> <span word="had">had</span> <span word="only">only</span> <span word="consisted">consisted</span> <span word="of">of</span> <span word="simple">simple</span> <span word="single">single</span>-<span word="celled">celled</span> <span word="life">life</span> <span word="forms">forms</span>. <span word="The">The</span> <span word="emergence">emergence</span> <span word="of">of</span> <span word="animals">animals</span> <span word="coincided">coincided</span> <span word="with">with</span> <span word="a">a</span> <span word="significant">significant</span> <span word="rise">rise</span> <span word="in">in</span> <span word="atmospheric">atmospheric</span> <span word="oxygen">oxygen</span>, <span word="and">and</span> <span word="therefore">therefore</span> <span word="it">it</span> <span word="seemed">seemed</span> <span word="obvious">obvious</span> <span word="to">to</span> <span word="link">link</span> <span word="the">the</span> <span word="two">two</span> <span word="events">events</span> <span word="and">and</span> <span word="conclude">conclude</span> <span word="that">that</span> <span word="the">the</span> <span word="increased">increased</span> <span word="oxygen">oxygen</span> <span word="levels">levels</span> <span word="had">had</span> <span word="led">led</span> <span word="to">to</span> <span word="the">the</span> <span word="evolution">evolution</span> <span word="of">of</span> <span word="animals">animals</span>.</p>
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