Mutsara kubva mufirimu «Mugwagwa»
Tinogona kunge takataura izwi rekuti "nyukiliya yechando" pane imwe nguva, semhedzisiro yechimwe chiitiko chakakomba kana chiitiko chemamiriro ekunze. Semuyenzaniso, chii chinotarisirwa kuitika kana iyo Campi Flegrei supervolcano. Iko kutonhora kamwe kamwe uko pasi raizotambura kwaizove nekufanana kukuru kune yechando chenyukireya. Asi chii chaizvo?
Rudzi urwu rwechando ipfungwa iyo inosanganisira inozotevera nguva yemamiriro ekunze yaizosara mushure mehondo yenyukireya. Mhedzisiro yacho ingave inoshamisa zvekuti chiitiko chinodaidzwa kuti "bhodhoro" chingamuka. Zvakapotsa ndiko kukurumidza kutsakatika kwezvikamu zvese kana zvidimbu zvemhando kana huwandu hwevanhu. Ichi chiitiko chinoguma mune izvo zvinonzi "genetic drift" iyo zvakare, inopesana, inokurudzira shanduko yemarudzi. Iwo mhedzisiro senge ketani yekuita iyo isina zvisikwa zvaizoponeswa, uye izvo kunyangwe vanhu vakafanirwa kupfuura munhoroondo yavo.
Mhedzisiro yechando chenyukireya
Muchidimbu, nguva yechando chenyukireya ndiyo mamiriro ekunze anokonzerwa nekushandiswa kwekusarudzika kwemabhomba enyukireya. Iko kutonhora kwepasirese kwaizouya kubva kwakakura guruva makore angakwira kumusoro kune stratosphere. Iyi nharaunda, iri pakati pegumi uye makumi mashanu emakiromita kukwirira, yaizadza nezvinhu izvo yaizodzivirira kufamba kwezuva. Kwete chete muhondo ine mabhomba eatomiki, zvinotevera kuti supervolcano yaizove nemhedzisiro imwechete nekuda kwemakoramu akakura ezvinhu zvakaburitswa kumusoro kwakakwirira.
Kusiyana neyakajairika nguva yechando yatinogona kuziva, izvi zvinogona kukonzera kudzikiswa pakupinda kwezuva. Kune zvipenyu zvinoita photosynthesis, zvaizoreva kufa zvachose kana kusarudzika kwemarudzi. Chimwe chinhu chisingatarisirwe ndechekuti, kunyangwe mhedzisiro yacho ichizivikanwa kunge inoparadza, iro gore reguruva aigona kugara kudenga kwemwedzi yakawanda. Zvakawanda sei, zvimwe kukuvara kune ecosystems. Kubva pakufa kwezvirimwa, yaizouya mushure mayo, kutsakatika kwekutsakatika zvichitevera chikafu cheni. Mushure mezvirimwa, zvipuka zvinouya, uye mumashure mavo zvinodya nyama. Zvinogoneka kuti zvichienderana nehukuru uye nenzvimbo, mweya usingarondedzeke pachawo wakonzera mhuka kufa pakarepo mumatunhu. Zvinoenderana nedzimwe dzidziso, chiitiko ichi chakashandiswawo senge tsananguro yekutsakatika kwemadinosaurs nemeteorite yakakonzera zvakafanana.
Bhodhoro rinoitika sei?
"Bhodhoro" ishoko rinoshandiswa mubhayoloji kureva nguva dzakapfuura uko, kuburikidza nhevedzano yezviitiko, huwandu hwezvisikwa hwakadzikiswa zvakanyanya muhuwandu uye hwakatosvika pakutsakatika. Izvo zvikonzero zvakajairira kuve zvinowanzo kuve zvichiperekedzwa neakakura njodzi. Saka tisati tambove nenhamba yakakura yevanhu ine hukuru hwakasiyana, zvino yave diki uye ine mutsauko mushoma.
Zvese izvi zvinotungamira kuti uone kuti mutsauko mudiki unotungamira kune a genetic drift, nekuda kwekufungidzira uye kushanduka kwekushanduka. Mune yega yeakarekodhwa eras, zvave zvakadaro. Vakapukunyuka pamatambudziko aya, senge mwaka wechando wenyukireya, vanowedzera kukurumidza kwavo kwemajini nekushanduka, zvichidaro vachigadzira mhando nyowani dzerudzi. Ruzhinji (kana rwakasimba kwazvo) hunhu hunogadzikana nekuenderera mberi, uye husina kusimba kana vashoma ndivo vanotsakatika.
Vanhu vakazviona rini?
Makore 75.000 apfuura. Inozivikanwa sedambudziko reToba, supervolcano iyi yakawanikwa muIndonesia yakaputika. Parizvino igungwa nekuda kwegomba hombe. Inofungidzirwa kuti mhando dzevanhu dzakaderedzwa kusvika kuzviuru zvishoma zvevanhu. Uye zvakare, kuderera kunoshanduka kwemamwe marudzi kunoenderana panguva imwe chete.
Kunyangwe isu takataura pamusoro pemakomo anoputika, nekuda kwehukama hwavo nenguva dzechando chenyukireya, zvinodzivirira zvakasiyana zvakanyanya. Ndokunge, ivo vaisakwanisa chete kubva pamamiriro ekunze, asi kumatambudziko kana madenda. Semuenzaniso, denda dema raigara kuMiddle Europe. Kana zvimwe, sekuputika, yakawanda nzara nezvirwere sezvazvakaitika muIceland nekuputika kweLake muna 1783.