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【Haveyoueverwonderedwhytherearesomanyskincolorsintheworld?Doyouknowwhypeoplelivinginparticularareasusuallyhaveacertaincolor?Biologyandhistoryarethetworeasonsforthis.Skincontainssomethingcalledmelaninw】
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问题描述:

Haveyoueverwonderedwhytherearesomanyskincolorsintheworld?Doyouknowwhypeoplelivinginparticularareasusuallyhaveacertaincolor?Biologyandhistoryarethetworeasonsforthis.

Skincontainssomethingcalledmelaninwhichdeterminesaperson’sskincolor.Themoremelaninapersonhasthedarkerhisorherskinwillbe.Theamountofandtheproductionofmelaninarecontrolledbygeneticsbutcanbeaffectedbyotherthingssuchassunlight.Ifapersonlivesinaplacewithlesssunlightaperson’sbodywillproducelessmelaninmakingtheskinlighter.

Skincolorisalsoaffectedbyanothersource----vitaminD.humansallneedvitaminDtobuildbones.PeoplecangetitbyeatingfoodssuchasfishandmilkorfromsunlightsosunlightabsorbedbymelanincannotbeusedforvitaminDproduction.Thereforeadark—skinnedpersonwillproducelessvitaminDthanalight—skinnedpersonwhentheyreceivedthesameamountofsunlight.

TheconnectionbetweenvitaminDproductionandskincolorisclearwhenwelookatevolution.TheearliesthumanslivedinAfricatheirdarkskinproducedlessvitaminDbecauseoftheirdarkskin.AsaresulttheirskinmadelessmelaninsotheycouldgetenoughsunlighttoproducevitaminD.theirskingraduallygotlighterandtheylosthair.NowpeoplelivinginareaswithstrongsunlightlikeAfricahavedarkerskinwhilepeoplelivinginotherareashavelighterskin.TheexceptiontothisistheInuitwholiveinaplacewithlittlesunlightbuthavedarkskinbecausetheyeatalotoffishandhaveenoughvitaminD.

Evolutionhasgivenusarainbowofskincolors.Humanshavealwayshadmelanintodetermineourskincolor.Whathaschangedthroughhistoryistheenvironmentwherewehavelived.Thishasinturnchangedourmelaninproductionandeventuallyskincolor.

Brief 1

Peoplelivinginaparticular 2 usuallyhavethesameskincolorandtherearemanydifferentskincolorsintheworld.

Reasonforskin color

Thereasonsfordifferentskincolorsmainly 3 inbiologyandhistory.

Biologyreasons

Theamountofmelaninbywhichaperson’sskincoloris__4 variesfrompeopleto people.Themoremel

蔡万景回答:
  【小题1】introduction【小题2】area【小题3】lie【小题4】determined【小题5】darker【小题6】affecting【小题7】produce【小题8】while【小题9】Conclusion【小题10】plays解析【小题1】归纳总结题。根据...
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