I te waenganui i 1910 me 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; ratou whakaaro whakamārama whiti ki te overage, me te hanga ira o te melaninophila puawai, i riro i te tauira tino whakamahia i roto i te mahi o Mendel. Na roto i te 1920s, i riro i te nuinga o te iwi i roto i te mahi o te whanaketanga tangata, i roto i te mahi o te whanaketanga, i te mea i kitea i roto i te rautau 20 i te raupapa whanui o te rauropi, i te nuinga o te iwi i roto i te tikanga tuku iho, i roto i te mahi o te whanaketanga, i kitea i roto i te raupapa o te rauropi, i roto i te raupapa o te rauropi, i whakaarohia i roto i
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