I waenganui i te 1910 me te 1915, Thomas Hunt Morgan me te "Drosophilists" i roto i tona rere taiwhanga hanga enei whakaaro e rua <unk>both tautohetohe<unk> i roto i te "Mendelian-chromosome ariā" o heredity. whanganga ratou i te āhuatanga o te hononga iranga, me te whakaarohia e noho ira i runga i te chromosomes rite i runga i te puawai; ka whakamārama ratou hypotheses whakawhiti ki te overage, me te hanga i te maori iranga o te melaninophila, i riro i te tauira tino whakamahia i roto i te mahi o Mendel. Na roto i te 1920s, i riro i te nuinga i roto i te whakaaro tuku iho i roto i te whanonga o te tangata. I roto i te mahi o te whanaketanga i roto i te rautau 20 i kitea i roto i te whanaketanga o te rauropi, i te nuinga o te iwi i roto i te tikanga tuku iho, i roto i te mahi o te rauropi i roto i te raupapa o te rauropi, i whakaarohia ki te rauropi i roto i te rauropi
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