Porofeseri Richard Dawkins, umuhanga w’icyamamare mu by’ubwihindurize, yaravuze ati “ubwihindurize ni ikintu kidashidikanywaho nk’uko tudashidikanya ko izuba ririho, rikaba ritanga ubushyuhe.”¹⁶ Kandi koko, ubushakashatsi hamwe n’ibigaragarira amaso byemeza ko izuba ritanga ubushyuhe. Ariko se, ubushakashatsi hamwe n’ibigaragarira amaso, byaba binashyigikira inyigisho y’ubwihindurize mu buryo budashidikanywaho?

Mbere yo gusubiza icyo kibazo, hari ikintu dukwiriye kubanza gusobanukirwa. Abahanga mu bya siyansi benshi babona ko uko ibinyabuzima bigenda byororoka, nyuma y’igihe, ibibikomotseho bishobora guhindukaho akantu gato cyane. Urugero, abantu bashobora gutoranya imbwa bakazibangurira ku zindi bidahuje ubwoko, hanyuma zikabwagura ibibwana bifite amaguru magufi cyangwa ubwoya burebure kuzirusha. a Utwo tuntu duto tugenda duhinduka, ni two abahanga mu bya siyansi bamwe na bamwe bita “ubwihindurize buciriritse.”

Nyamara abashyigikira inyigisho y’ubwihindurize bavuga ko iryo hinduka rito cyane ryagiye ribaho mu myaka ibarirwa muri za miriyari, ryaje kubyara ihinduka rikomeye cyane ryatumye amafi ahinduka intubutubu, inguge zigahinduka abantu. Ibyo bavuga ko ari ihinduka rikomeye, babyita “ubwihindurize buhambaye.”

Urugero, Charles Darwin yigishije ko ihinduka rito dushobora kubona n’amaso yacu, ryumvikanisha ko n’ihinduka rikomeye rishobora kubaho, nubwo  nta muntu urabibona.¹⁷ Kuri we, ibinyabuzima bito cyane byabayeho mbere y’ibindi, byagiye bihindukaho “utuntu duto cyane” mu gihe cy’imyaka itabarika, biza kuvamo amoko y’ibinyabuzima biri ku isi abarirwa muri za miriyoni.¹⁸

Abantu benshi babona ko ibyo Darwin yavuze ari byo. Baribaza bati ‘niba mu bwoko runaka bw’ibinyabuzima hashobora kubaho ihinduka mu rugero ruto, ese nyuma y’igihe kirekire cyane, ubwihindurize ntibwatuma habaho ihinduka rikomeye?’ b Mu by’ukuri, inyigisho y’ubwihindurize ishingiye ku binyoma bitatu. Tekereza kuri ibi bikurikira.

Ikinyoma cya 1. Ihinduka ry’imiterere ni yo mpamvu y’ibanze ituma habaho ubwoko bushya bw’ibinyabuzima. Inyigisho y’“ubwihindurize buhambaye” ishingiye ku gitekerezo kivuga ko ihinduka ry’imiterere, rishobora gutuma habaho ubwoko bushyashya bw’ibimera cyangwa inyamaswa. Iryo hinduka ry’imiterere ni ihinduka ry’ingirabuzima fatizo zigena uko ikinyabuzima kizaba giteye, ribaho mu buryo bw’impanuka mu bimera no mu nyamaswa.¹⁹

Ukuri. Ibyinshi mu bigize imiterere y’ibimera cyangwa inyamaswa biba bikubiye mu mabwiriza ari mu ngirabuzima fatizo zigena imiterere y’ibinyabuzima, ari cyo gishushanyo mbonera kiba mu ntima ya buri ngirabuzima fatizo. c Abashakashatsi bavumbuye ko iryo hinduka ry’imiterere y’ingirabuzima fatizo zigena uko ikinyabuzima kizaba giteye, rishobora gutuma ibimera n’inyamaswa bitandukana ho gato n’ibibikomotseho. Ariko se koko, iryo hinduka rituma habaho ubwoko bushya bw’ibinyabuzima? Ese ubushakashatsi bumaze ikinyejana bukorwa ku ngirabuzima fatizo zigena imiterere y’ibinyabuzima, bwagaragaje iki?

Mu mpera y’imyaka ya za 30, abahanga mu bya siyansi bungutse ikindi gitekerezo gishya. Bari basanzwe batekereza ko ibinyabuzima bishobora kwihanganira imimerere bibamo, ari byo byonyine bishobora kubaho kandi bikororoka. Ibyo byashobokaga ari uko habayeho ihinduka ry’ingirabuzima fatizo zigena imiterere yabyo, ariko byose bikabaho mu buryo bw’impanuka. Bumvaga rero ko ibyo byatumye habaho ubundi bwoko bw’ibimera. Noneho batangiye gutekereza ko umuntu aramutse agize uruhare muri iryo hinduka, byatuma haboneka ubwoko bushya bw’ibinyabuzima burusha ubwo bwakomotseho kuba bwiza. Wolf-Ekkehard Lönnig, umuhanga mu bya siyansi wo mu kigo cyo mu Budage cyitiriwe Max Planck, gikora ubushakashatsi mu birebana no kubangurira ibimera, d yaravuze ati “abahanga mu binyabuzima, abashakashatsi ku miterere y’ingirabuzima fatizo zigena imiterere y’ibinyabuzima, cyane cyane abakora ubushakashatsi mu birebana no kubangurira ibimera cyangwa inyamaswa, bose barabishishikariye cyane.” Bari bashishikajwe n’iki? Lönnig wamaze imyaka igera kuri 30 yiga ibirebana n’ihindagurika ry’imiterere y’ingirabuzima fatizo zigena imiterere y’ibimera, yaravuze ati “abo bashakashatsi batekerezaga ko igihe cyari kigeze kugira ngo bahindure uburyo bwari busanzwe bwo kubangurira ibihingwa cyangwa inyamaswa. Batekerezaga ko baramutse bagize  uruhare mu gutoranya ibishobora guhangana n’imimerere bibamo kurusha ibindi maze bakabibangurira, bagera ku bwoko bushya kandi bwiza kurushaho bw’ibimera n’inyamaswa.”²⁰ Hari abari biringiye ko bazatuma habaho andi moko mashya y’ibimera n’inyamaswa.

Abahanga mu bya siyansi bo muri Leta Zunze Ubumwe z’Amerika, muri Aziya no mu Burayi, batangije porogaramu z’ubushakashatsi zatwaye amafaranga menshi cyane, batekerezaga ko zizihutisha ubwihindurize mu bimera no mu nyamaswa. Imihati myinshi bashyizeho mu gihe cy’imyaka isaga 40 y’ubushakashatsi yageze ku ki? Umushakashatsi witwa Peter von Sengbusch yavuze ko “nubwo ubwo bushakashatsi bwatwaye amafaranga atagira ingano, imihati bashyizeho bashaka kugera ku bwoko bw’ibimera bishobora kwera cyane kurusha ubundi, bakoresheje imirase [kugira ngo batume habaho ihinduka ry’imiterere y’ingirabuzima fatizo], yose yabaye imfabusa.”²¹ Lönnig na we yaravuze ati “mu myaka ya za 80 ni ho icyizere ndetse n’ishyaka abahanga mu bya siyansi bo ku isi hose bari bafite byayoyotse, nta cyo bagezeho. Ibihugu byo mu Burengerazuba bw’isi byahagaritse porogaramu z’ubushakashatsi ku birebana no kubangurira ibimera cyangwa inyamaswa binyuze mu guhindura ingirabuzima fatizo zigena imiterere yabyo. Ibimera n’inyamaswa bagezeho muri ubwo buryo bw’ibangurira, hafi ya byose . . . byarapfuye cyangwa ugasanga bidafite ubuzima bwiza ugereranyije n’ibisanzwe.” e

Bityo rero, ibyavuye mu bushakashatsi bwakozwe mu gihe cy’imyaka igera ku 100 ku ihinduka ry’ingirabuzima fatizo zigena imiterere y’ibinyabuzima, cyane cyane ubwakozwe mu gihe cy’imyaka 70 ku bihereranye no kubangurira ibimera cyangwa inyamaswa binyuze mu guhindura ingirabuzima fatizo zigena imiterere yabyo, byatumye abahanga mu bya siyansi bagira imyanzuro bafata, ku birebana no kumenya niba iryo hinduka ry’imiterere y’ingirabuzima fatizo rishobora gutuma habaho ubwoko bushya bw’ibinyabuzima. Lönnig amaze gusuzuma ibyagezweho, yaravuze ati “ihinduka ry’imiterere y’ingirabuzima fatizo, ntirishobora gutuma ubwoko bwari busanzwe buriho, [bwaba ubw’ibimera cyangwa ubw’inyamaswa], buhinduka ngo bubyare ubundi bwoko bushya butandukanye n’ubwa mbere. Uwo mwanzuro uhuje n’ibyagezweho mu bushakashatsi bwose bwakozwe mu kinyejana cya 20, ku bihereranye n’ihinduka ry’imiterere y’ingirabuzima fatizo ndetse bikanahuza n’igenekereza.”²²

None se, ihinduka ry’imiterere y’ingirabuzima fatizo rishobora gutuma habaho ubwoko bushya bw’ibinyabuzima butandukanye n’ubwa mbere? Birumvikana ko bidashoboka. Ubushakashatsi bwa Lönnig bwatumye agera ku mwanzuro w’uko “ubwoko runaka bw’ibinyabuzima, buba bufite ingirabuzima fatizo zihariye zitandukanye n’ingirabuzima fatizo z’ubundi bwoko, ku buryo ihinduka iryo ari ryo ryose ry’ingirabuzima fatizo zabwo ryabaho mu buryo bw’impanuka, ridashobora kugira icyo ribuhinduraho.”

Noneho tekereza icyo ayo magambo yumvikanisha. Abahanga mu bya siyansi baminuje ntibashoboye kurema ubwoko bushya bw’ibinyabuzima, binyuze mu gutoranya ibimera n’inyamaswa bagahindura ingirabuzima fatizo zabyo. Ese utekereza ko ibintu bibaye mu buryo bw’impanuka ari byo byatuma habaho ubwoko bushya bw’ibinyabuzima? Niba ubushakashatsi bwaragaragaje ko ihinduka ry’imiterere y’ingirabuzima fatizo ridashobora gutuma habaho ubwoko bushya bw’ibinyabuzima, “ubwihindurize buhambaye” bwo bwashoboka bute?

Ikinyoma cya 2. Ubushobozi ibinyabuzima bifite bwo kwihanganira imimerere y’aho biba, bwatumye habaho ubundi bwoko bushya bw’ibinyabuzima. Darwin yemeraga ko ibinyabuzima birusha ibindi ubushobozi bwo kwihanganira imimerere y’aho biba ari byo byakomeje kubaho, mu gihe ibidafite ubwo bushobozi byo byageraga aho bigapfa. Muri iki gihe, abemera ubwihindurize bigisha ko, uko amoko y’ibinyabuzima yagiye atatana akaba ukwayo, ibinyabuzima byakomeje kubaho ari ibyari bifite ingirabuzima fatizo zishobora guhinduka, zigatuma bigira ubushobozi bwo kwihanganira imimerere y’aho hantu hashya biri. Ibyo bituma abemera ubwihindurize bibwira ko ayo matsinda y’ibinyabuzima yagiye kuba ukwayo, yagiye yihinduriza akaza guhinduka ubwoko bushya bw’ibinyabuzima.

Ukuri. Nk’uko twabibonye, ibyagezweho mu bushakashatsi bigaragaza neza ko ihinduka ry’ingirabuzima fatizo, ridashobora gutuma habaho ubwoko bushya bw’ibimera n’inyamaswa. None se, ni  iyihe gihamya abemera ubwihindurize batanga bemeza ko iyo ingirabuzima fatizo zihindutse kugira ngo ikimera cyangwa inyamaswa gishobore guhuza n’imimerere y’aho kiba, amaherezo ibyo bituma habaho ubwoko bushya bw’ibinyabuzima? Mu mwaka wa 1999, ikigo cyo muri Amerika gikora ubushakashatsi mu bya siyansi (NAS), cyanditse agatabo kavuga iby’“ubwoko 13 bw’inyoni Darwin yakoreyeho ubushakashatsi mu birwa bya Galápagos (izo nyoni zitiriwe Darwin).”²³

Mu myaka ya za 70, itsinda ry’abashakashatsi ryari riyobowe na Peter R. na B. Rosemary Grant bo muri Kaminuza ya Princeton, ryize iby’izo nyoni, basanga ko nyuma y’amapfa yateye kuri icyo kirwa akamara umwaka, inyoni zifite umunwa ujya kuba munini ari zo zarokotse ayo mapfa bitagoranye kurusha izifite umunwa muto. Kubera ko kwitegereza ubunini bw’umunwa w’izo nyoni n’uburyo uteye ari bumwe mu buryo bw’ingenzi bwo gutandukanya ubwo bwoko 13 bw’inyoni, bumvaga ko bavumbuye ikintu cy’ingirakamaro cyane. Ako gatabo kasohowe n’icyo kigo (NAS) gakomeza kavuga ko “Grant n’abo bari kumwe batekerezaga ko kuri ibyo birwa hagiye haba amapfa buri myaka icumi, mu myaka 200 gusa ibyo byazatuma havuka ubwoko bushya bw’izo nyoni.”²⁴

Icyakora, ako gatabo kasohowe n’icyo kigo (NAS) ntikavuze ko mu myaka yakurikiye ayo mapfa, inyoni zo muri ubwo bwoko zifite umunwa muto ari zo zabaye nyinshi. Abashakashatsi baje kubona ko iyo imiterere y’ibihe ihindutse kuri icyo kirwa, inyoni zo muri ubwo bwoko zifite umunwa munini ziba nyinshi mu mwaka umwe, ariko nyuma yaho izifite umunwa muto zikongera kuzirusha ubwinshi. Nanone baje kubona ko zimwe mu nyoni zo muri ayo matsinda yombi zibangurirana, zikabyara ibyana bizirusha ubushobozi bwo guhangana n’imimerere y’aho ziba. Bashoje bavuga ko izo nyoni zo muri ayo matsinda yombi zikomeje kujya zibangurirana, byazagera ubwo ayo matsinda yombi ahinduka itsinda rimwe gusa.²⁵

None se ubushobozi ibinyabuzima bifite bwo kwihanganira imimerere bibamo, butuma habaho ubundi bwoko bushya bw’ibinyabuzima? Mu myaka ibarirwa muri za mirongo ishize, George Christopher Williams, umuhanga mu binyabuzima wemera ubwihindurize, yatangiye kubishidikanyaho.²⁶ Mu mwaka wa 1999, Jeffrey H. Schwartz, umwe mu bashyigikira inyigisho y’ubwihindurize, yanditse ko ubushobozi ibinyabuzima bifite bwo kwihanganira imimerere bibamo, wenda bushobora kubifasha guhangana n’imimerere igenda ihindagurika, ariko avuga ko budashobora gutuma habaho ubundi bwoko bushya bw’ibinyabuzima.²⁷

Mu by’ukuri, za nyoni zitiriwe Darwin ntizihinduka “ikindi kintu gishya.” Zikomeza kuba za zindi. Kuba zishobora kubangurirana hagati yazo, bituma umuntu ashidikanya ku buryo bumwe  na bumwe abigisha iby’ubwihindurize bakoresha basobanura icyo “ubwoko” ari cyo. Ikindi kandi, iby’izo nyoni bigaragaza ko ibigo by’abahanga mu bya siyansi byemerwa cyane, na byo bishobora gutanga raporo itagaragaza ukuri kose ku bushakashatsi bakoze.

Ikinyoma cya 3. Ibisigazwa by’inyamaswa n’ibimera byataburuwe bigaragaza ko habayeho ubwihindurize buhambaye. Ka gatabo twavuze kanditswe n’ikigo gikora ubushakashatsi mu bya siyansi (NAS), gatuma ugasomye asigara atekereza ko ibisigazwa by’inyamaswa n’ibimera abahanga mu bya siyansi bataburuye, bitanga ibihamya bihagije by’uko habayeho “ubwihindurize buhambaye.” Kavuga ko “havumbuwe ibisigazwa by’ibinyabuzima biri hagati y’amafi n’intubutubu, ibiri hagati y’intubutubu n’ibikururanda, ibiri hagati y’ibikururanda n’inyamabere hamwe n’uruhererekane rw’inguge, ku buryo akenshi usanga bitoroshye kumenya neza igihe ubwoko bumwe bwahindukiye bukaba ubundi.”²⁸

Ukuri. Ayo magambo icyo kigo cy’ubushakashatsi (NAS) cyavuganye icyizere aratangaje. Kubera iki? Niles Eldredge, umwe mu bashyigikira cyane inyigisho y’ubwihindurize, avuga ko ibyo bisigazwa by’inyamaswa n’ibimera byataburuwe bitagaragaza ko ubwihindurize bwagiye bubaho buhoro buhoro mu bwoko runaka bw’inyamaswa n’ibimera, ahubwo ko hashoboraga gushira igihe kirekire cyane “hahindutse utuntu duto mu bwoko runaka bw’inyamaswa n’ibimera, cyangwa se nta n’igihindutse.” f²⁹

Kugeza ubu, ku isi hose abahanga mu bya siyansi bataburuye kandi babarura ibisigazwa binini by’inyamaswa bigera kuri miriyoni magana abiri, n’utundi dusigazwa duto duto tw’inyamaswa tubarirwa muri za miriyari. Abenshi mu bashakashatsi bemeranya kuri iki: ibyo bisigazwa byinshi byerekana ko amatsinda y’ingenzi y’inyamaswa yabereyeho icyarimwe, ndetse agakomeza kubaho nta cyo ahindutseho kigaragara, kandi ko hari amoko menshi y’inyamaswa yagize atya akazimira nk’uko yaje.

Kuki abenshi mu bantu b’ingenzi bashyigikira ubwihindurize bakomeza kwemeza ko “ubwihindurize buhambaye” ari ikintu cyabayeho? Richard Lewontin, umuhanga wemerwa cyane mu bashyigikira ubwihindurize, yanditse avuga ko abahanga benshi mu bya siyansi baba biteguye kwemera ibitekerezo byo mu rwego rwa siyansi, nyamara bidashobora kubonerwa ibihamya, bakabyemera bitewe n’uko “ari abayoboke bakomeye b’inyigisho ivuga ko ibiriho byose mu isanzure ry’ikirere, hakubiyemo n’ibinyabuzima byose, byibeshejeho ubwabyo gusa, bidasabye uruhare rw’izindi mbaraga ziturutse ahandi.” Abahanga mu bya siyansi benshi banga no gutekereza ko haba hariho Umuhanzi w’umuhanga, bashingiye ku byo Lewontin yanditse agira ati “ntidushobora kwemera ko hariho Umuremyi.”³⁰

Kuri iyo ngingo, hari ikinyamakuru cyanditse ibyavuzwe na Rodney Stark, umuhanga mu by’imibanire y’abantu, wavuze ko “hashize imyaka 200 bagerageza kwemeza rubanda ko ushaka kuba umuhanga mu bya siyansi wese, agomba kwitandukanya n’iby’iyobokamana iyo biva bikagera.” Yongeyeho ko muri kaminuza zazobereye mu gukora ubushakashatsi, “abantu bemera Imana batabigaragaza.”—Scientific American.³¹

Kugira ngo wemere ko ubwihindurize buhambaye bwabayeho koko, byasaba ko ubanza no kwemera ko iyo abahanga mu bya siyansi b’abemeragato ndetse n’abatemera Imana basobanura ibintu byo mu rwego rwa siyansi baba bavumbuye, badashingira ku byo bo ubwabo basanzwe bemera. Byasaba ko wemera ko ihinduka ry’imiterere y’ingirabuzima fatizo hamwe n’ubushobozi ibinyabuzima bifite bwo kwihanganira imimerere y’aho biba, ari byo byatumye habaho ibinyabuzima byose tuzi, nubwo ubushakashatsi bwamaze ikinyejana cyose bwagaragaje ko ihinduka ry’imiterere y’ingirabuzima fatizo, ritigeze rituma hagira ubwoko na bumwe bw’ibinyabuzima buhindukamo ubundi bwoko bushya butandukanye n’ubwa mbere. Byagusaba kandi kwemera ko ibyaremwe byose byagiye byihinduriza bihereye ku kinyabuzima kimwe, nubwo ibisigazwa by’inyamaswa n’ibimera byataburuwe bigaragaza mu buryo budashidikanywaho, ko amoko y’ingenzi y’ibimera n’inyamaswa yabereyeho icyarimwe kandi ko atigeze yihinduriza ngo abyare andi moko mashya, nubwo hashize imyaka itabarika abayeho. Ese urumva imyizerere nk’iyo yaba ishingiye ku kuri cyangwa yaba ishingiye ku kinyoma? Mu by’ukuri, kwemera ubwihindurize ni “ukwizera” nk’ukundi kose.