Me yasa kwakwalwa ta yi raguwa a girman idan aka kwatanta da baya?

Me yasa kwakwalwa ta yi raguwa a girman idan aka kwatanta da baya?

Juyin halittar kwakwalwar dan Adam an dade ana daukarsa a matsayin mafi girman siffa ta karuwar hankalin dan Adam da kuma mamaye duniya, tare da shekaru miliyan biyu da suka wuce na juyin halittar dan Adam da aka kwatanta da kusan ninki hudu a girman kwakwalwa.

Amma ƙarin shaidun da aka samu kwanan nan sun nuna cewa kwakwalwar ɗan adam ta canza ta hanyar da ba a yi tsammani ba, tana raguwa a wani lokaci bayan ƙarshen lokacin ƙanƙara na ƙarshe, masana kimiyya sun bayyana.

Dangane da haka, Jeremy De Silva, farfesa a fannin nazarin halittu a kwalejin Dartmouth, ya bayyana cewa, galibin mutane sun yi imanin cewa ci gaban kwakwalwa yana faruwa ne ta hanyar da ta dace yayin da take girma, sannan ta samu kwanciyar hankali, sannan ta tsaya daga baya, ya yi nuni da cewa wannan ba gaskiya ba ne, a matsayin mutane. sun rasa kyallen kwakwalwa kwatankwacin girman lemo daya.

Don gano hakan, ƙungiyar masu binciken da de Silva ke jagoranta sun yi amfani da haɗaɗɗen bayanan burbushin halittu da na zamani don tantance cewa asarar al'amarin toka ya faru tsakanin shekaru 3000 zuwa 5000 da suka wuce, bisa ga binciken da aka buga a watan Yuni a cikin mujallar Frontiers in Ecology and Juyin Halitta.

Ingancin al'ummomi sun taka rawa

Da farko masana ilmin dan Adam sun yi zaton cewa sauye-sauyen sun zo daidai da bullar ayyukan noma kimanin shekaru 10000 da suka wuce, da kuma kawar da farauta da tarawa a duniya.

Yayin da kwanakin baya-bayan nan na kungiyar DeSilva ke nuni da gagarumin zamani na dadadden wayewa a Arewacin Afirka, Gabas ta Tsakiya, da Kudancin Amurka, al'ummomi masu sarkakiya da suka yi imani mai yiwuwa sun taka rawa wajen raguwar da ke faruwa a cikin kwakwalwa.

Masana kimiyya sun ba da rahoton cewa kwakwalwar ɗan adam ta kasance kusan girman ɗaya a matsakaici, kusan santimita 1450 cubic, a cikin shekaru 150 da suka gabata, a cewar Wall Street Journal.

Yayin da wannan matsakaita ya ragu da sauri da kusan 10%, ko kuma har zuwa santimita cubic 150, cikin ƴan shekaru dubu da suka gabata.

Rage girman ɗan adam

Ƙungiyar DeSilva ta gano cewa girman kwakwalwar ɗan adam ba kawai yana raguwa ba, amma har ma ya ragu dangane da girman jiki, yana nuna cewa rage girman kwakwalwa ba kawai samfurin jikinmu na raguwa ba ne.

Masu binciken sun ba da shawarar cewa buƙatarmu ta kula da babban kwakwalwa, don kiyaye bayanai game da abinci, alaƙar zamantakewa, mafarauta da muhallinmu, wataƙila ma sun ragu cikin 'yan shekaru dubu da suka gabata saboda mun sami damar adana bayanai a waje a cikin sauran membobin. na zamantakewa da'ira, birane da zamantakewa kungiyoyin.

Hakanan ana iya samun ƙarfafa yanayin ta hanyar amfani da littattafai, na'urori na sirri da kuma Intanet a matsayin tushen bayanai iri ɗaya, a cewar Chris Stringer, masanin burbushin halittu a Gidan Tarihi na Tarihi da ke Landan, da Christoph Koch, masanin kimiyyar jijiyoyin jiki a Cibiyar Allen. , wata cibiya ce a Seattle.

Ko da yake matsakaicin tsayin ɗan adam yana da alama ya karu a cikin ƴan ƙarni da suka gabata, Stringer ya ce nau'ikan mu sun zama gajarta sosai, sun fi sauƙi kuma sun fi ƙanƙanta a cikin shekaru XNUMX da suka gabata yayin da yanayin ya yi zafi, kuma girman kwakwalwa ya ragu sosai.

"Amma wannan bazai zama duka labarin ba," in ji shi.

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