Kamar yadda muka sani sosai, nau'ikan karnuka daban-daban suna da halaye daban-daban da ke shafar yanayin jikinsu da halayensu, a tsakanin sauran fannoni. Ofaya daga cikinsu shine tsinkayen rayuwa, tunda gabaɗaya magana kananan karnuka rayuwa tsawon rai fiye da na babban irin. A yau, ilimin kimiyya ya ba da labarin tasirin 'yanci kyauta tare da wannan gaskiyar kuma yana nazarin wasu ra'ayoyin.
Nazarin Jami'ar Colgate
A farkon shekara, sakamakon binciken da aka gudanar ta Josh Winward da Alex Ionescu, daga Jami'ar Colgate da ke New York. Hisungiyar tasa ta tattara kusan nau'ikan samfurin 80 daga ppan kwikwiyo da suka mutu kwanan nan da karnukan manya, manya da ƙanana. Sun kebe kwayoyin daga wadannan ragowar kuma suka kirkiresu a dakin bincike domin bincike.
Da wannan, suka gano cewa maye gurbin manyan kwikwiyo ya fi sauri, saboda yana cinye adadin kuzari idan aka kwatanta shi da ƙananan karnuka. Wannan yana haifar da haɓaka matakan su free radicals, wanda zai iya haifar da lalacewar kwayar halitta, tunda samarda abubuwan kara kuzari don yakar su bai isa ba. Duk wannan yana gajarta rayuwar dabba.
Maganar hormonal
Wata ka'ida ta danganta hormone da ake kira IGF-1, wanda aka fi sani da haɓakar haɓaka 1, yanzu a cikin dukkan dabbobi masu shayarwa. Yana da alhakin motsa kwayar halitta da ninkawa, don haka duk wani canji a ciki yana shafar girman dabbar. Hakanan, yana da alaƙa da cututtuka kamar su cutar kansa da matsalolin zuciya da jijiyoyin jini. Dogsananan karnuka suna da ƙananan matakan wannan hormone, wanda zai iya bayyana dalilin da yasa suke tsufa a hankali fiye da manyan karnuka.
Girman zuciya dangane da nauyin jiki
Dangane da girmansu, manyan karnuka suna da karamar zuciya fiye da kananan dabbobi. Akwai wata ka'ida da ba a tabbatar da ita ba wacce ta danganta tsawon rayuwar manyan karnuka tare da cewa dole su fitar da jini mai yawa ga jikinsu, don haka zuciyarsu ta fi shan wahala.