《经济学人》：赤道的鸟羽毛颜色比靠近两极的更鲜艳？
原文标题：
Evolution
Bird-swatching
Songbirdsgetmorecolourfultheclosertheylivetotheequator
A19th-centuryhypothesisconfirmedatlast
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WHENTHEPrussiannaturalistAlexandervonHumboldtarrivedinSouthAmericain,thecoloursastonishedhim.“Lookattheblossoms,thebirds,”hewrote.“Eventhecrayfishareblueandyellow.”
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Intheinterveningcenturies,Humboldt’smusingshavemorphedintoaninformal,ifcontroversial,hypothesisabouttheworld’slivingthings:thatorganismsinequatorialclimesaremorecolourfulthanthosenearerthepoles.
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InanewpaperinNatureEcologyEvolution,ChrisCooney,anevolutionarybiologistattheUniversityofSheffield,andcolleaguesatBritain’sNaturalHistoryMuseumcollectioninTring,offerwhattheycallthemost