{"id":38308,"date":"2019-11-18T03:41:58","date_gmt":"2019-11-18T00:41:58","guid":{"rendered":"https:\/\/bilimvegelecek.com.tr\/?p=38308"},"modified":"2019-11-14T10:58:38","modified_gmt":"2019-11-14T07:58:38","slug":"australopitekuslar-kac-turle-temsil-ediliyordu-biyolojik-cesitlilikleri-nasildi","status":"publish","type":"post","link":"https:\/\/bilimvegelecek.com.tr\/index.php\/2019\/11\/18\/australopitekuslar-kac-turle-temsil-ediliyordu-biyolojik-cesitlilikleri-nasildi","title":{"rendered":"Australopitekus\u2019lar ka\u00e7 t\u00fcrle temsil ediliyordu, biyolojik \u00e7e\u015fitlilikleri nas\u0131ld\u0131?"},"content":{"rendered":"

Afrika\u2019da ge\u00e7 miyosen ve pliyosen d\u00f6nemle ya\u015f\u0131t \u00e7ok ilkel g\u00f6r\u00fcn\u00fcml\u00fc hominid\u2019lerin son y\u0131llarda bilim d\u00fcnyas\u0131na kazand\u0131r\u0131lmas\u0131yla ailemizin k\u00f6keni ve evrimi hakk\u0131ndaki g\u00f6r\u00fc\u015flerimizde k\u00f6kl\u00fc de\u011fi\u015fiklikler oldu. Australopitekus<\/em>\u2019lar kaba ve narin yap\u0131l\u0131 olmak \u00fczere iki temel gruba ayr\u0131l\u0131r.\u00a0 A\u015fa\u011f\u0131 yukar\u0131 d\u00f6rt milyon y\u0131l boyunca, Do\u011fu ve G\u00fcney Afrika\u2019da ya\u015fam\u0131\u015f bu insans\u0131lar\u0131n, son y\u0131llardaki \u00e7ok de\u011ferli buluntularla beraber bilindi\u011finden \u00e7ok daha fazla t\u00fcrsel \u00e7e\u015fitlilik g\u00f6sterdi\u011fi, farkl\u0131 davran\u0131\u015f \u00f6r\u00fcnt\u00fcleri ve anatomik \u00f6zelliklere sahip olduklar\u0131 anla\u015f\u0131lm\u0131\u015ft\u0131r. \u00d6zellikle Sudan\u2019\u0131n g\u00fcneybat\u0131s\u0131nda Bahr el Ghazal b\u00f6lgesinde bulunan ve 3-3,5 milyon y\u0131l \u00f6ncesiyle tarihlenen insans\u0131 fosiller sayesinde insan ailesinin be\u015fi\u011fi olarak sadece G\u00fcney ve Do\u011fu Afrika de\u011fil, ayn\u0131 zamanda Orta Afrika\u2019y\u0131 da dikkate alman\u0131n gere\u011fi ortaya \u00e7\u0131km\u0131\u015ft\u0131r. Her ne kadar farkl\u0131 t\u00fcrler s\u00f6z konusu olsa da, bunlar\u0131n yine de ortak \u00f6zellikleri vard\u0131r.<\/p>\n

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Kaba yap\u0131l\u0131 Australopitekus\u2019un etlendirilmi\u015f hali.<\/figcaption><\/figure>\n

Onca t\u00fcrsel \u00e7e\u015fitlili\u011fe ra\u011fmen biz, Australopitekus<\/em>\u2019lar\u0131 simgeleyen \u00fc\u00e7 \u00f6zelli\u011fin, k\u00fc\u00e7\u00fck beyin, iri y\u00fcz ve iki ayak \u00fczerinde y\u00fcr\u00fcme (bipedalizm) oldu\u011funu s\u00f6yleyebiliriz. \u0130nsans\u0131lar\u0131n t\u00fcrlerini tan\u0131mlarken bunlar aras\u0131ndaki filogenetik ili\u015fkiye de de\u011finmek gerekir. Ayr\u0131ca, bunlar\u0131n zamansal ve mek\u00e2nsal da\u011f\u0131l\u0131m\u0131 da \u00e7ok \u00f6nemlidir. Hi\u00e7 ku\u015fkusuz bu t\u00fcrler i\u00e7erisinden biri Homo <\/em>ad\u0131n\u0131 verdi\u011fimiz insana giden evrimsel \u00e7izgiyi olu\u015fturdu; di\u011ferleri yok oldu.<\/p>\n

Narin yap\u0131l\u0131lar: <\/strong>Z\u00d6 3 ile 2 milyon y\u0131l aras\u0131nda ya\u015fad\u0131klar\u0131 tahmin edilmektedir. Do\u011fu ve G\u00fcney Afrika\u2019daki kaz\u0131larda g\u00fcn \u0131\u015f\u0131\u011f\u0131na \u00e7\u0131kar\u0131lm\u0131\u015flard\u0131r. Adlar\u0131ndan da anla\u015f\u0131laca\u011f\u0131 \u00fczere narin yap\u0131l\u0131 insans\u0131lar ortalama 1,29 m boyunda, 24- 25 kg a\u011f\u0131rl\u0131\u011f\u0131nda idiler. Beyinleri 450 cm3 hacminde idi. Narin yap\u0131l\u0131 terimi sadece insans\u0131 i\u00e7in anlam ifade eder; zira bu t\u00fcr\u00fcn temsilcileri biz modern insanlarla kar\u015f\u0131la\u015ft\u0131r\u0131ld\u0131\u011f\u0131nda y\u00fcz ve di\u015fler a\u00e7\u0131s\u0131ndan olduk\u00e7a kaba say\u0131l\u0131r.<\/p>\n

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Narin yap\u0131l\u0131 Australopitekus.<\/figcaption><\/figure>\n

\u00d6\u011f\u00fct\u00fcc\u00fc di\u015fleri bizimkilerin iki kat\u0131 irili\u011findeydi. 20 ya\u015f di\u015fleri de bizimkiler gibi k\u00fc\u00e7\u00fclme e\u011filimi g\u00f6stermiyordu. K\u00f6pekdi\u015fleri di\u011fer kesici di\u015flerle ayn\u0131 hizada olup, iri primatlar\u0131n iri par\u00e7alay\u0131c\u0131 \u00f6zelli\u011fi ile uzaktan yak\u0131ndan hi\u00e7bir ilgisi yoktu. Di\u015fler, irilikleri ve ufak baz\u0131 morfolojik ayr\u0131nt\u0131lar\u0131 bir kenara b\u0131rak\u0131lacak olursa, temelde modern insan\u0131nkine b\u00fcy\u00fck \u00f6l\u00e7\u00fcde benzer. Zaten insanla\u015fma s\u00fcrecinde en h\u0131zl\u0131 de\u011fi\u015fime u\u011frayan organ di\u015ftir. Narin yap\u0131l\u0131 insans\u0131larda, kafatas\u0131ndaki kas ba\u011flant\u0131 izleri de belirgin de\u011fildir. Y\u00fcz, beyne oranla iri olup \u00f6ne do\u011fru \u00e7\u0131k\u0131nt\u0131 yapar. Bilindi\u011fi gibi, insanla\u015fma s\u00fcrecinde ba\u015flang\u0131\u00e7ta k\u00fc\u00e7\u00fck bir beyin ve iri bir y\u00fcze tan\u0131k olunurken, zamanla ili\u015fki tersine d\u00f6nm\u00fc\u015f; beyin irile\u015firken y\u00fcz ufalm\u0131\u015f ve sonu\u00e7ta modern insandaki g\u00f6r\u00fcn\u00fcm\u00fcn\u00fc alm\u0131\u015ft\u0131r. Narin yap\u0131l\u0131lar\u0131n di\u015fi ve erkekleri aras\u0131nda belirgin irilik fark\u0131 vard\u0131r. Erkek ve kad\u0131n aras\u0131ndaki bu belirgin c\u00fcsse fark\u0131 evrim esnas\u0131nda giderek azalm\u0131\u015f, bug\u00fcn en az d\u00fczeye inmi\u015ftir.\"\"<\/p>\n

\"\"
\u00dcstte narin yap\u0131l\u0131 Australopitekus kafatas\u0131 ve altta etlendirilmi\u015f hali.<\/figcaption><\/figure>\n

Kaba yap\u0131l\u0131lar: <\/strong>Bug\u00fcnk\u00fc bilgilerimizin \u0131\u015f\u0131\u011f\u0131nda Z\u00d6 2,6 milyon y\u0131l ile 1,2 milyon y\u0131l aras\u0131nda ya\u015fam\u0131\u015flard\u0131r. Bu durumda tarih sahnesine narin yap\u0131l\u0131lardan daha ge\u00e7 \u00e7\u0131km\u0131\u015f say\u0131l\u0131rlar. Do\u011fu Afrika\u2019da ya\u015fayan kaba yap\u0131l\u0131lar Australopitekus<\/em> boisei <\/em>t\u00fcr\u00fc alt\u0131nda, G\u00fcney Afrika\u2019dakiler ise Australopitekus robustus<\/em> t\u00fcr\u00fc alt\u0131nda dikkate al\u0131n\u0131r. Boylar\u0131 1,50-1,60 m aras\u0131nda de\u011fi\u015fir. Beyinleri 500-600 cm3 hacminde idi. \u0130ri di\u015fler, g\u00fc\u00e7l\u00fc \u00e7i\u011fneme kaslar\u0131 kaba yap\u0131l\u0131lar\u0131n \u00e7enelerine ola\u011fan\u00fcst\u00fc bir k\u0131rma, ezme ve \u00f6\u011f\u00fctme g\u00fcc\u00fc katm\u0131\u015ft\u0131r. Kemik, kas ve di\u015f sistemi etkin bir \u00e7i\u011fneme i\u015flevine yan\u0131t verecek bi\u00e7imde do\u011fal ay\u0131klanma s\u00fcrecinden ge\u00e7mi\u015f ve sonu\u00e7ta kaba yap\u0131l\u0131lardaki anatomik olu\u015fum ortaya \u00e7\u0131km\u0131\u015ft\u0131r. Do\u011fu ve G\u00fcney Afrika\u2019daki narin ve kaba yap\u0131l\u0131 insans\u0131lar uzun s\u00fcre ayn\u0131 ortam\u0131 payla\u015ft\u0131. Peki, nas\u0131l olmu\u015ftu da bu iki t\u00fcr birbirini yok etmeden y\u00fcz binlerce y\u0131l bir arada ya\u015famay\u0131 ba\u015farm\u0131\u015ft\u0131? Acaba bu birlikteli\u011fin temelinde ayn\u0131 b\u00f6lgelerde farkl\u0131 beslenme al\u0131\u015fkanl\u0131klar\u0131n\u0131 s\u00fcrd\u00fcrme olgusu mu yat\u0131yordu? Dikkatler bu iki t\u00fcr\u00fcn fosillerinde di\u015flerin \u00e7i\u011fneme y\u00fczeylerine yeniden \u00e7evrildi.<\/p>\n

Taramal\u0131 elektronik mikroskop sayesinde \u00e7i\u011fneme y\u00fczeylerindeki a\u015f\u0131nma bi\u00e7imleri ayr\u0131nt\u0131l\u0131 olarak incelendi. Narin yap\u0131l\u0131lar\u0131n di\u015flerinde yo\u011fun bi\u00e7imde \u00e7iziklere rastlan\u0131rken, kaba yap\u0131l\u0131lar\u0131nkinde hem \u00e7izik, hem de \u00e7ukurlar birlikte saptand\u0131. Ara\u015ft\u0131r\u0131c\u0131lar, di\u015f a\u015f\u0131nma y\u00fczeylerinin taramal\u0131 elektronik mikroskop analizinden hareketle narin yap\u0131l\u0131lar\u0131n daha ziyade yumu\u015fak meyve ve yaprak t\u00fcr\u00fc besinlerle beslendiklerini, kaba yap\u0131l\u0131lar\u0131n ise a\u011f\u0131rl\u0131kl\u0131 olarak f\u0131nd\u0131k vb. sert kabuklu yemi\u015flerle, sert bitki k\u00f6kleriyle ve yumrular\u0131yla beslendiklerini ileri s\u00fcrd\u00fc. Gerek kaba, gerekse narin yap\u0131l\u0131lar\u0131n basit bi\u00e7imde avland\u0131klar\u0131 ve \u00f6ld\u00fcrd\u00fckleri k\u00fc\u00e7\u00fck hayvanlar\u0131, ate\u015fi kullanmay\u0131 bilmedikleri i\u00e7in pi\u015firmeden yedikleri san\u0131lmaktad\u0131r.<\/p>\n

Arkaik yap\u0131l\u0131lar: <\/strong>\u0130nsan ailesinin tarihinin ilk kan\u0131tlar\u0131 Do\u011fu ve Orta Afrika\u2019da bulunmu\u015ftur. Biz, \u015fu ana kadar bu tarihin i\u00e7inde yer alan kaba ve narin insans\u0131lar\u0131 tan\u0131d\u0131k. Peki, bunlar\u0131n atalar\u0131 kimlerdi? \u0130\u015fte bilim d\u00fcnyas\u0131 bu soruya yan\u0131t bulmak amac\u0131yla 1970\u2019lerden itibaren ara\u015ft\u0131rmalar\u0131n\u0131 bu b\u00f6lgelerde, \u00f6zellikle Etiyopya\u2019da Hadar y\u00f6resinde yo\u011funla\u015ft\u0131rd\u0131. 1973 y\u0131l\u0131nda nihayet beklenen an geldi ve insans\u0131lar\u0131n ailesine, arkaik insans\u0131lar ad\u0131 alt\u0131nda \u00fc\u00e7\u00fcnc\u00fc bir t\u00fcr kat\u0131ld\u0131: Australopitekus afarensis<\/em>. Fosiller Hadar\u2019da kurumu\u015f bir g\u00f6l yata\u011f\u0131nda g\u00fcn \u0131\u015f\u0131\u011f\u0131na \u00e7\u0131kar\u0131ld\u0131. Burada yakla\u015f\u0131k 35 Afarensis <\/em>bireyine ait kal\u0131nt\u0131 s\u00f6z konusu idi.<\/p>\n

Afarensis \u00a0<\/em>insans\u0131lar\u0131 Z\u00d6 3,6-3 milyon y\u0131l aras\u0131nda ya\u015fam\u0131\u015ft\u0131. Bu durumda, son y\u0131llarda \u00c7ad\u2019\u0131n Bahr el Ghazal b\u00f6lgesinde bulunan bir ba\u015fka insans\u0131 t\u00fcr\u00fc ile \u00e7a\u011fda\u015f oluyorlard\u0131.<\/p>\n

Afarensis<\/em>\u2019ler aras\u0131nda Lucy ad\u0131yla bilinen 1 m boyunda 20-25 kg a\u011f\u0131rl\u0131\u011f\u0131nda 3,4 milyon y\u0131l \u00f6nce ya\u015fad\u0131\u011f\u0131 saptanan bir de di\u015fi vard\u0131. \u0130skeleti olduk\u00e7a iyi korunmu\u015ftu, ama kafatas\u0131 t\u00fcmlenecek kadar iyi durumda de\u011fildi. Ancak, daha sonraki y\u0131llarda ayn\u0131 b\u00f6lgede y\u00fcr\u00fct\u00fclen kaz\u0131 \u00e7al\u0131\u015fmalar\u0131 sayesinde Lucy\u2019nin \u00e7a\u011fda\u015f\u0131 olan iyi korunmu\u015f bir kafatas\u0131 ele ge\u00e7ti.Arkaik insans\u0131lar kaba ve narin yap\u0131l\u0131lardan daha eski ve do\u011fal olarak onlardan daha ilkel \u00f6zelliklere sahipti. Bunlar\u0131n di\u015fleri insandakinden ziyade goril ve \u015fempanze gibi iri primatlar\u0131nkini \u00e7a\u011fr\u0131\u015ft\u0131r\u0131yordu. Birinci alt k\u00fc\u00e7\u00fck az\u0131 ile alt k\u00f6pekdi\u015finin morfolojisi insandakine hi\u00e7 benzemiyordu. \u00d6zellikle k\u00f6pekdi\u015fi, kesici di\u015flerin seviyesinden daha yukardayd\u0131. Beyin 400 cm3 irili\u011finde idi. Bu durumda di\u011fer hominid t\u00fcrlerininkinden daha k\u00fc\u00e7\u00fck say\u0131l\u0131rd\u0131.<\/p>\n

\"\"
Kaba yap\u0131l\u0131 Australopitekus.<\/figcaption><\/figure>\n

Erkek ve di\u015fi Afarensis<\/em>\u2019ler aras\u0131nda \u00e7ok belirgin bir c\u00fcsse fark\u0131 vard\u0131. Afarensis <\/em>insans\u0131lar\u0131 sadece Hadar b\u00f6lgesinde ya\u015famad\u0131; t\u00fcrde\u015flerine ait fosil kal\u0131nt\u0131lar 1977 y\u0131l\u0131nda Kenya\u2019n\u0131n Laetoli b\u00f6lgesinde de g\u00fcn \u0131\u015f\u0131\u011f\u0131na \u00e7\u0131kar\u0131ld\u0131. B\u00f6lgedeki volkanik t\u00fcfler i\u00e7inde sertle\u015ferek g\u00fcn\u00fcm\u00fcze kadar koruna gelen ayak izleri, dik y\u00fcr\u00fcyen insans\u0131lardan ba\u015fkas\u0131na ait de\u011fildi. Di\u011fer parmaklar\u0131n yan\u0131nda yer alan ba\u015fparmak, topu\u011fun b\u0131rakt\u0131\u011f\u0131 iz ve ayak taban\u0131 kemeri iki ayak \u00fczerinde y\u00fcr\u00fcd\u00fcklerinin en g\u00fczel kan\u0131tlar\u0131yd\u0131. Yakla\u015f\u0131k 70 m\u2019lik bir pist \u00fczerinde izlenen ayak izleri bir \u00e7ocuk ve iki eri\u015fkine aitti.<\/p>\n

Arkaik insans\u0131lara ait bug\u00fcne kadar gerek Kenya\u2019da, gerekse Cibuti\u2019de ele ge\u00e7en fosiller, bu insans\u0131lar\u0131n de\u011fi\u015fik ekolojik ko\u015fullara uyum sa\u011flad\u0131klar\u0131n\u0131 akla getirmektedir. Ufak yap\u0131l\u0131yd\u0131lar ve k\u00fc\u00e7\u00fck bir beyne sahiplerdi. G\u00f6r\u00fcn\u00fcm olarak di\u011fer insans\u0131larla iri primatlar aras\u0131nda bir yere oturtulabilirlerdi. 3,6 milyon y\u0131l \u00f6ncesinde, bizler kadar olmasa da dik y\u00fcr\u00fcyor ve ellerini serbest\u00e7e kullanabiliyorlard\u0131.<\/p>\n

Kaynak: <\/strong>Metin \u00d6zbek, \u0130nsan\u0131n Tarih \u00d6ncesi Evrimi, Bilim ve Gelecek Kitapl\u0131\u011f\u0131, Eyl\u00fcl 2019, 5. Bask\u0131.s.62-67<\/p>\n","protected":false},"excerpt":{"rendered":"

Afrika\u2019da ge\u00e7 miyosen ve pliyosen d\u00f6nemle ya\u015f\u0131t \u00e7ok ilkel g\u00f6r\u00fcn\u00fcml\u00fc hominid\u2019lerin son y\u0131llarda bilim d\u00fcnyas\u0131na kazand\u0131r\u0131lmas\u0131yla ailemizin k\u00f6keni ve evrimi hakk\u0131ndaki g\u00f6r\u00fc\u015flerimizde k\u00f6kl\u00fc de\u011fi\u015fiklikler oldu. Australopitekus\u2019lar kaba ve narin yap\u0131l\u0131 olmak \u00fczere iki temel gruba ayr\u0131l\u0131r.\u00a0 A\u015fa\u011f\u0131 yukar\u0131 d\u00f6rt milyon y\u0131l boyunca, Do\u011fu ve G\u00fcney Afrika\u2019da ya\u015fam\u0131\u015f bu insans\u0131lar\u0131n, son y\u0131llardaki \u00e7ok de\u011ferli buluntularla beraber […]<\/p>\n","protected":false},"author":429,"featured_media":38309,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_acf_changed":false,"footnotes":""},"categories":[19],"tags":[5551,5550,200,816,1967],"class_list":["post-38308","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-bilim-gundemi","tag-afarensis","tag-australopitecus","tag-evrim","tag-fosil","tag-kanit"],"acf":[],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t