Halittar mutum ta jinsin daya bata canzawa zuwa wani jinsi yayin rayuwa. Amma tambayar me yasa birrai basu canzawa zuwa mutane abin birgewa bane, saboda yana taimakawa tunani game da rayuwa, juyin halitta da kuma me ake nufi da mutum.
Yanayi na sanya iyaka
Duk da adadi mai ban mamaki da nau'ikan nau'ikan daban-daban, baligi daga jinsin daya yawanci baya haduwa da wani baligi daga wani jinsi (duk da cewa wannan ba gaskiya bane ga tsirrai, kuma akwai sanannun keɓaɓɓu ga dabbobi).
A wata ma'anar, ana samar da kyankyaso na yara masu launin toka mai launin toka ta hanyar manyan zakakuran hadaddiyar zakara maimakon Manjo Mitchell.
Hakanan ya shafi wasu nau'ikan, waɗanda ba su bayyana mana haka ba. Akwai nau'ikan kudaje masu fruita ,an itace, fruita fruitan fruita fruitan itace (fan ƙanana ƙuda waɗanda ke da sha'awar fruitsa fruitsan itace ruɓaɓɓe, musamman ayaba) waɗanda suke kamanceceniya da kamanni.
Amma maza da mata na jinsunan Drosophila daban-daban basa samarda sabbin kudaje.
Dabbobi basa canzawa da yawa, amma duk da haka suna canzawa, wani lokacin kuma akan wani ɗan gajeren lokaci (misali, sakamakon canjin yanayi). Wannan ya kawo tambaya mai matukar ban sha'awa game da yadda halittu ke canzawa da kuma yadda sabbin jinsuna ke fitowa.
Ka'idar Darwin. Shin muna dangi ne da biri ko a'a
Kimanin shekaru 150 da suka wuce, Charles Darwin ya ba da bayani mai gamsarwa a cikin The Origin of Species. An soki aikinsa a lokacin, a wani ɓangare saboda ba a fahimci dabarunsa da kyau ba. Misali, wasu mutane sun yi tunanin cewa Darwin ya ba da shawarar cewa bayan wani lokaci, birai sun zama mutane.
Labarin ya ci gaba da cewa a yayin tattaunawa mai dadi da jama'a da aka yi 'yan watanni bayan wallafa littafin The Origin of Species, Oxford Bishop Samuel Wilberforce ya tambayi Thomas Huxley, abokin Darwin, "Kakansa ko kakarsa biri ne?"
Wannan tambayar ta gurbata ka'idar Darwin: birrai ba su juyewa zuwa mutane, amma dai mutane da birai suna da magabata daya, don haka akwai kamanceceniya a tsakaninmu.
Ta yaya muka bambanta da kifin kifi? Nazarin kwayoyin halittar da ke dauke da bayanan da suka sa muka zama mu ya nuna cewa chimpanzees, bonobos, da mutane suna da irin wannan kwayoyin.
A hakikanin gaskiya, bonobos da chimpanzees sune dangi na kurkusa da mutane: magabatan mutane sun rabu da magabatan chimpanzee kimanin shekaru miliyan biyar zuwa bakwai da suka gabata. Bonobos da chimpanzees sun zama nau'ikan halittu biyu daban daban kwanan nan kamar shekaru miliyan biyu da suka gabata.
Muna kamanceceniya, kuma wasu mutane suna jayayya cewa wannan kamanceceniya ya isa ga chimpanzees suna da haƙƙoƙi iri ɗaya da na mutane. Amma, tabbas, mun bambanta sosai, kuma mafi bambancin bayyananniyar shine wanda ba kasafai ake ganinsa kamar ilimin ɗabi'a ba.
