▁in ▁the ▁str atum ▁cor neum ▁and ▁fat ▁cells ▁of ▁der mis ▁and ▁super f icial ▁fas cia . ▁Hem og lo bin ▁( also ▁sp elled ▁ha em og lo bin ): ▁It ▁is ▁found ▁in ▁blood ▁and ▁is ▁not ▁a ▁p ig ment ▁of ▁the ▁skin ▁but ▁develop s ▁a ▁pur ple ▁color . ▁O xy hem og lo bin : ▁It ▁is ▁also ▁found ▁in ▁blood ▁and ▁is ▁not ▁a ▁p ig ment ▁of ▁the ▁skin . ▁It ▁develop s ▁a ▁red ▁color . ▁ ▁There ▁is ▁a ▁correlation ▁between ▁the ▁ge ographic ▁distribution ▁of ▁U V ▁radiation ▁( U V R ) ▁and ▁the ▁distribution ▁of ▁ind igen ous ▁skin ▁p ig ment ation ▁around ▁the ▁world . ▁Are as ▁that ▁highlight ▁higher ▁amounts ▁of ▁U V R ▁reflect ▁dark er - sk inned ▁populations , ▁generally ▁located ▁near er ▁towards ▁the ▁equ ator . ▁Are as ▁that ▁are ▁far ▁from ▁the ▁trop ics ▁and ▁closer ▁to ▁the ▁pol es ▁have ▁lower ▁concentration ▁of ▁U V R , ▁which ▁is ▁reflected ▁in ▁l ighter - sk inned ▁populations . ▁ ▁In ▁the ▁same ▁population ▁it ▁has ▁been ▁observed ▁that ▁adult ▁human ▁females ▁are ▁consider ably ▁l ighter ▁in ▁skin ▁p ig ment ation ▁than ▁males . ▁Fem ales ▁need ▁more ▁calci um ▁during ▁pre gn ancy ▁and ▁la ct ation , ▁and ▁vit amin ▁D ▁which ▁is ▁synth es ized ▁from ▁sun light ▁helps ▁in ▁absor bing ▁calci um . ▁For ▁this ▁reason ▁it ▁is ▁thought ▁that ▁females ▁may