Binciken kwayoyin halitta na baya-bayan nan ya nuna yadda dabbobi masu shayarwa na farko suka sami hangen nesa na dare don bunƙasa a cikin duniyar da dabbobi masu rarrafe suka mamaye.
Kuna da idanu na kwarai. Kamar mahaifiyarka. A haƙiƙa, dukanmu muna da idanu na musamman, kamar danginmu na nesa. Ba wai suna da kyau ba (ko da yake na tabbata da gaske idanunku ne), amma sun yi fice saboda yawan mazugi. Waɗannan cones ne (masu ɗaukar hoto na ido) waɗanda ke ba ku damar ganin nau'ikan launuka iri-iri waɗanda ba su samuwa ga kare ku. Bincike na baya-bayan nan ya nuna cewa makantar kalar karen ka ta samo asali ne tun a zamanin Dinosaur, wanda ke tabbatar da cewa ga dabbobi masu shayarwa, ido wata taga ce a zamanin juyin halitta.
Idanu sun samo asali ne da sifofi daban-daban, tare da dabaru daban-daban da iyawa daban-daban. An san kwari da idanunsu masu ban sha'awa, waɗanda suka ƙunshi raka'o'in karɓar haske da yawa waɗanda aka haɗa tare don ƙirƙirar ƙirar duniya. Ko da sun bambanta a cikin tsarin su, daga mayar da hankali zuwa matsayi, parabolic ko superfaceted.
A matsayinmu na dabbobi masu shayarwa, mun fi kusa da idanu masu sauƙi, waɗanda kuma suna da wurare iri-iri na ban mamaki. Idanun rami, kamar yadda sunan ke nunawa, wani nau'i ne mai sauƙi na idon ido wanda aka sanya shi a cikin soket, kuma mai yiwuwa yayi kama da farkon idanu masu sauƙi. Gilashin ruwan tabarau da idanu masu yawa na iya samar da hoto mai kaifi kuma ana samun su a cikin gastropods (kamar katantanwa) da cephalopods (kamar dorinar ruwa). Yawancin kashin bayan ƙasa, da suka haɗa da dabbobi masu shayarwa, dabbobi masu rarrafe, da tsuntsaye, suna da idanu masu rarrafe tare da cornea mai raɗaɗi wanda ke ɗauke da mummunan ruwan tabarau wanda ke ƙara girman hoton da aka zayyana a bayan ido. A can ne ake sarrafa hasken ta hanyar retina, wani yanki na sel masu daukar hoto masu haske wanda ke aika sakonni ta hanyar jijiyar gani zuwa kwakwalwa. Galibi dabbobi suna ganin haka.
Ɗaya daga cikin kura-kurai da yawa na masana halitta shine cewa sun yi imani cewa bambancin ido alama ce ta hannun allahntaka mai shiryarwa. Ta yaya wani abu mai rikitarwa zai iya faruwa a hankali a cikin jerin maye gurbi? Menene amfanin rabin ido? Duk da haka, wannan gaba-da-ko-ko-ko-ko-ko-ko-ni-ka-ni-ka-yi game da juyin halittar ido ya yi watsi da kewayon hanyoyi da rikitattun hangen nesa a cikin nau'in dabbobin da ke duniya a tsawon lokaci.
Idanu sun sami kansu a ƙalla sau arba'in a tsawon tarihin rayuwa. A takaice dai, babu wani kakanni daya da ya raya ido wanda duk wasu idanuwa suke gangarowa daga gare shi, amma kakanni dayawa a cikin zuriyar dabbobi masu yawa. Bayyanar sifofin iri ɗaya akai-akai a cikin ƙungiyoyin dabbobin da ba su da alaƙa ba sabon abu bane ko ma abin mamaki bane. Bayan haka, muna da ginshiƙan sinadarai iri ɗaya na rayuwa kuma dukkanmu suna da saurin kamuwa da maye gurbi daga tsara zuwa tsara, don haka ba abin mamaki ba ne cewa ƙungiyoyi da yawa za su iya “tuntuɓe” wani “sabon” ci gaba. Idan ya zama mai riba, tabbas za a ajiye shi, domin yana taimakawa dabbar ta tsira. Idanu suna da matsayi mai girma akan jerin halaye na zahiri masu amfani ga yawancin halittu masu rai, masu motsi.
Kwayoyin da ke da haske na retina na kashin baya suna da manyan nau'i biyu: cones da sanduna. Cones ba su da hankali ga haske, amma suna ba da damar dabbobi su bambanta tsakanin launuka ta gano tsayin tsayin haske daban-daban. A gefe guda kuma, sanduna sun fi damuwa a cikin ƙananan haske, amma ga lalacewar ƙuduri. Idanun dukan dabbobi sun ƙunshi lambobi daban-daban na sanduna da mazugi a cikin kwayar ido. Wataƙila kun yi tsammanin sanduna za su fara tasowa, daga baya kuma su rikiɗe zuwa madaidaicin mazugi masu launi-bayan haka, fim ɗin hoto na baƙi da fari ya zo kafin launi. A gaskiya ma, akasin haka ma gaskiya ne: masu ɗaukar hoto masu siffar mazugi sun fara bayyana, sannan sanduna suka ɓullo daga gare su, har ma da yin amfani da tsarin mazugi na retina.
Yawancin vertebrates, irin su kifi, tsuntsaye, da dabbobi masu rarrafe (saboda haka kusan dinosaur), suna da nau'i mai yawa a cikin retina kuma suna iya gano haske mai fadi. A daya bangaren kuma, galibin dabbobi masu shayarwa suna da sanduna da yawa da mazugi, wadanda ke rage hangen nesa amma suna ba da hangen nesa mai kyau a cikin karamin haske. Launuka masu launi a cikin dabbobi masu shayarwa ana kiran su protanopia kuma yana hana su bambanta sassan ja-yellow-kore na bakan haske. Primates ɗaya ne daga cikin ƴan dabbobi masu shayarwa masu kyakkyawar fahimtar launi godiya ga kwafin kwayoyin halittar opsin a cikin kakanninmu. Opsins sunadaran sunadaran haske ne a cikin sel masu ɗaukar hoto na retina waɗanda ke canza haske zuwa siginar lantarki. Wannan kwafi da aka yi a kakanninmu ya ba su damar tantance launi kuma ana tunanin ya ba su fa'idar rayuwa wajen neman 'ya'yan itace da suka ci a cikin daji.
Me yasa yawancin dabbobi masu shayarwa suke ganin duniyarmu a cikin duhu? Dalili na rinjayen sanduna a cikin dabbobi masu shayarwa ana tsammanin komawa zuwa lokacin tarihinmu na farko, tsakanin shekaru 225-65 da suka wuce (Mesozoic). Dabbobi masu rarrafe irin su Dinosaur sun yi mulkin duniya a wancan lokacin, amma suma na farkon dabbobi masu shayarwa sun fara tun daga wannan lokacin. Sun bunƙasa a ko'ina cikin Mesozoic, ba wai kawai suna rayuwa a cikin shekaru miliyan 150 ba kamar yadda danginsu na nesa suke ba, amma har ma sun tsira daga abin da ya faru na Cretaceous-Paleogene wanda ya kawo karshen rayuwar sauran vertebrates a ƙarshen Cretaceous.
Koyaya, samun nasarar zama tare da dabbobi masu rarrafe na Mesozoic yana da sakamako ga waɗannan farkon dabbobi masu shayarwa. Irin waɗannan dabbobi masu shayarwa ba su da girma: kaɗan ne suka fi girma fiye da fox, yawancin sun fi ƙanƙanta. Duk da haka, abubuwa masu kyau suna zuwa a cikin ƙananan fakiti, kuma waɗannan majagaba masu shayarwa sun yi amfani da kyawawan abubuwan da muke gani a cikin ƙananan dabbobi a yau: sun binne kamar moles, suna hawan bishiyoyi kamar squirrels, kuma suna iyo kamar doki. Amma akwai wata bidi'a da ta shafi hangen nesa kai tsaye: sun fara gudanar da rayuwar dare.
An yi imani da cewa kasancewar dare yana ɗaya daga cikin manyan sabbin abubuwa na kakanninmu. Ƙara dogaro ga wari shine ɗayan abubuwan da ke haifar da haɓakar girman kwakwalwar, kuma gashin gashin su ya ba su damar jure yanayin sanyi na sa'o'i 24 na duniya. Yawancin dabbobi masu rarrafe mai yiwuwa sun kasance na rana (aiki a rana), suna barin duhu zuwa masu shayarwa masu tawali'u. An ambaci wannan lokacin juyin halittar dabbobi masu shayarwa " hasashe na butulcin dare" (hasashen bakin kwalbar dare). Duk wani maye gurbi na bazuwar da ke inganta hangen nesa kaɗan zai ba wa waɗannan dabbobi fa'idar rayuwa ta musamman.
Wannan shine yadda kakanninmu na d ¯ a masu shayarwa suka sami hangen dare.
Wannan bayanin makantar launi a cikin dabbobi masu shayarwa ya wuce zato kawai: y labarin kwanan nan An gabatar da shaidar nazarin halittu don tallafawa wannan ka'idar. Ta hanyar nazarin yadda kwayoyin halittar da ke daidaita ci gaban sanduna suke bayyana a farkon matakan girma a cikin beraye, sannan kuma kwatanta su da kifin zebra, masanan sun sami damar nuna tsarin nazarin halittu wanda ya mayar da mammalian cones zuwa sanduna. Samun ikon nuna wannan muhimmin tabbaci ne na ka'idar cewa dabbobi masu shayarwa na farko sun zama dare.
Wannan haɗuwa da hangen nesa na dare da haɓakar ƙwaƙwalwa, tare da sauye-sauyen hakori da kwarangwal, sun ba da gudummawa ga gagarumar nasarar da dabbobi masu shayarwa. Wannan ya ba su damar yin amfani da abubuwan da suka shafi muhalli na musamman, suna bunƙasa tare da dinosaur na miliyoyin shekaru, daga ƙarshe ya wuce su. Lokacin da dinosaur suka tafi, dabbobi masu shayarwa sun mamaye rana, sun karu da girma kuma sun zama daban-daban.
Budgie na iya ganin launuka fiye da kare ku, godiya ga gwagwarmayar rayuwa tsakanin kakanninsu na da: dinosaur da dabbobi masu shayarwa na farko. Primates sun sake gano bakan launi, amma a cikin kwayoyin halittarmu suna ɓoye gadon wannan "ƙarancin dare": sawun kwayoyin halitta wanda ke kaiwa zuwa ga maye gurbi wanda ya taɓa tabbatar da amfani ga rayuwa.
Muna ba da shawarar cewa ku karanta kuma ku lura da duk abin da aka yanke akan tashar mu bisa ga ra'ayin ku. Kada ku yi maganin kai! A cikin labaranmu, muna tattara sabbin bayanan kimiyya da kuma ra'ayoyin masana masu iko a fannin kiwon lafiya. Amma ku tuna: likita ne kawai zai iya tantancewa kuma ya rubuta magani.
An yi niyya ta hanyar tashar don masu amfani fiye da shekaru 13. Wasu kayan ƙila ba za su dace da yara masu ƙasa da shekara 16 ba. Ba ma tattara bayanan sirri daga yara a ƙarƙashin 13 ba tare da izinin iyaye ba.Muna da ƙaramin buƙata. Muna ƙoƙari don ƙirƙirar abun ciki mai inganci wanda ke taimakawa kula da dabbobi, kuma muna ba da shi kyauta ga kowa da kowa saboda mun yi imani cewa kowa ya cancanci ingantaccen bayani mai amfani.
Tallace-tallacen kuɗaɗen talla yana ɗaukar ƙaramin yanki na farashin mu, kuma muna son ci gaba da samar da abun ciki ba tare da buƙatar ƙara talla ba. Idan kun sami amfanin kayanmu, don Allah tallafa mana. Yana ɗaukar minti ɗaya kawai, amma tallafin ku zai taimaka mana mu rage dogaro ga talla da ƙirƙirar labarai masu fa'ida. Na gode!
