生物谷報(bào)道：日本東京大學(xué)博物館的Gen Suwa的研究小組在埃塞俄比亞發(fā)現(xiàn)了距今大約1000萬(wàn)年前的大猩猩的牙齒化石，從而可能將人類(lèi)與大猩猩的進(jìn)化分歧時(shí)間提前至少200萬(wàn)年,。這種大猩猩命名為Chororapithecus abyssinicus,。這項(xiàng)新發(fā)現(xiàn)公布在8月23日的《自然》雜志上,。
日本的這個(gè)研究小組在距離埃塞俄比亞首都亞的斯亞貝巴約170公里的沙漠灌木林地區(qū)發(fā)現(xiàn)了9顆古大猩猩牙齒化石——8顆臼齒和一顆犬齒。研究人員推測(cè)這些牙齒至少來(lái)源于三個(gè)以上的個(gè)體,。
研究人員通過(guò)比較研究發(fā)現(xiàn),，這些牙齒在尺寸、各部分比例以及內(nèi)部結(jié)構(gòu)掃描結(jié)果上與現(xiàn)代大猩猩亞種的牙齒均沒(méi)有明顯差別,。研究小組得出結(jié)論認(rèn)為,，大猩猩與人類(lèi)進(jìn)化分歧的時(shí)間不應(yīng)該是早先認(rèn)為的800萬(wàn)年前，而應(yīng)該是比1000萬(wàn)年或1100萬(wàn)年前更早一些,。而且,，在功能上，這些牙齒似乎正在進(jìn)化,。
這一發(fā)現(xiàn)具有重大的意義,，它將幫助填補(bǔ)化石證據(jù)上的巨大空白，并將人類(lèi)與大猩猩的進(jìn)化分歧時(shí)間向前提前了至少200萬(wàn)年,。另外,，它將促使人類(lèi)學(xué)家和遺傳學(xué)家重新確定原始人類(lèi)與黑猩猩的進(jìn)化分歧時(shí)間。
Suwa教授還表示,，本次發(fā)現(xiàn)的牙齒化石再一次表明了非洲才是人類(lèi)與現(xiàn)代非洲猿類(lèi)的共同起源地,，而不是一些人認(rèn)為的歐亞大陸。
不過(guò),，也有科學(xué)家對(duì)此次結(jié)果表示懷疑,。美國(guó)伊利諾斯大學(xué)研究靈長(zhǎng)類(lèi)動(dòng)物牙齒的古人類(lèi)學(xué)家Jay Kelley表示，他并不確信這些牙齒的主人是大猩猩,。還需要更多的化石證據(jù),、分析以及討論等來(lái)確定此次發(fā)現(xiàn)的新種是否原始人類(lèi)的祖先。眼下為了謹(jǐn)慎起見(jiàn),，他并不會(huì)輕易使用該新種標(biāo)本來(lái)重排原始人類(lèi)與大猩猩以及黑猩猩的進(jìn)化分歧時(shí)間,。
2003年秋天，美國(guó)亞特蘭大“耶基斯國(guó)家靈長(zhǎng)類(lèi)動(dòng)物研究中心”的薩拉-布洛斯南和弗蘭斯德瓦爾發(fā)現(xiàn),，僧帽猴不愿意服從它們認(rèn)為對(duì)自己不公平的待遇,。兩人在試驗(yàn)中發(fā)現(xiàn)，一只猩猩在得到自己期望得到的一粒葡萄或者不太期望得到的一根黃瓜后,，都會(huì)看看同伴得到的是什么東西,。那些從出生后一直生活在一起的猩猩，即使得到不太想要的黃瓜一般也不會(huì)做出負(fù)面反應(yīng)人,，但剛認(rèn)識(shí)不久的猩猩通常會(huì)有比較強(qiáng)烈的反應(yīng),。而且，共同生活時(shí)間不長(zhǎng)的猩猩,，如果和同伴干了一件同樣的工作,，但是得到的獎(jiǎng)賞卻沒(méi)有同伴好，它一般不愿意再去做這件工作,。布洛斯南認(rèn)為：“人類(lèi)所做的決定趨向于情感化,，往往因?yàn)閷?duì)象的不同而變化。”而在這一點(diǎn)上,，猩猩和人類(lèi)相似,。
原始出處:
Nature 448, 921-924 (23 August 2007) | doi:10.1038/nature06113; Received 18 June 2007; Accepted 25 July 2007
A new species of great ape from the late Miocene epoch in Ethiopia
Gen Suwa1, Reiko T. Kono2, Shigehiro Katoh3, Berhane Asfaw4 & Yonas Beyene5
The University Museum, the University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
Department of Anthropology, National Museum of Nature and Science, Hyakunincho, Shinjuku-ku, Tokyo 169-0073, Japan
Division of Natural History, Hyogo Museum of Nature and Human Activities, Sanda, Hyogo 669-1546, Japan
Rift Valley Research Service, P.O. Box 5717, Addis Ababa, Ethiopia
Department of Archaeology and Paleontology, Authority for Research and Conservation of Cultural Heritage, Ministry of Culture and TourismP.O. Box 13247, Addis Ababa, Ethiopia
Correspondence to: Gen Suwa1 Correspondence and requests for materials should be addressed to G.S. (Email: [email protected]).
With the discovery of Ardipithecus, Orrorin and Sahelanthropus1, 2, 3, 4, 5, 6, 7, our knowledge of hominid evolution before the emergence of Pliocene species of Australopithecus8, 9 has significantly increased, extending the hominid fossil record back to at least 6 million years (Myr) ago. However, because of the dearth of fossil hominoid remains in sub-Saharan Africa spanning the period 12–7 Myr ago, nothing is known of the actual timing and mode of divergence of the African ape and hominid lineages. Most genomic-based studies suggest a late divergence date—5–6 Myr ago and 6–8 Myr ago for the human–chimp and human–gorilla splits, respectively10, 11, 12, 13, 14—and some palaeontological and molecular analyses hypothesize a Eurasian origin of the African ape and hominid clade15, 16. We report here the discovery and recognition of a new species of great ape, Chororapithecus abyssinicus, from the 10–10.5-Myr-old deposits of the Chorora Formation at the southern margin of the Afar rift. To the best of our knowledge, these are the first fossils of a large-bodied Miocene ape from the African continent north of Kenya. They exhibit a gorilla-sized dentition that combines distinct shearing crests with thick enamel on its 'functional' side cusps. Visualization of the enamel–dentine junction by micro-computed tomography reveals shearing crest features that partly resemble the modern gorilla condition. These features represent genetically based structural modifications probably associated with an initial adaptation to a comparatively fibrous diet. The relatively flat cuspal enamel–dentine junction and thick enamel, however, suggest a concurrent adaptation to hard and/or abrasive food items. The combined evidence suggests that Chororapithecus may be a basal member of the gorilla clade, and that the latter exhibited some amount of adaptive and phyletic diversity at around 10–11 Myr ago.
