從靈長類動物到直立人種，人類緣何得以進化,？原因可能很復(fù)雜,。美國研究人員6月4日報告說，大約350萬年前原始人類開始“吃草”,，飲食習慣的變化可能是人類進化過程中的重要一步,。
美國科羅拉多大學等機構(gòu)的研究人員4日在美國《國家科學院學報》報告說，他們利用碳同位素技術(shù),，對來自東非的原始人類和狒狒等靈長類動物的牙釉質(zhì)化石樣本進行了分析。結(jié)果發(fā)現(xiàn),，大約350萬年前,，原始人類的飲食結(jié)構(gòu)發(fā)生了變化，食用熱帶草和莎草明顯增加,。
科羅拉多大學教授馬特·施蓬海默說,，400萬年前，原始人類的飲食結(jié)構(gòu)還和猩猩類似,，主要以果實和一些葉片為食,；大約350萬年前，一些原始人類確實開始食用熱帶草和莎草等新食物。
不過,，研究人員表示,，碳同位素技術(shù)無法確定原始人類食用熱帶草或莎草的具體部分，原始人類究竟食用這些植物的種子,、枝葉或是根莖還不知曉,。
研究人員指出，原始人類開始吃草,，可能標志著他們與猩猩等其他靈長類動物的脫離,。研究人員說：“長期以來飲食是人類進化的一種驅(qū)動力，飲食變化關(guān)聯(lián)著腦容量變大和直立行走的出現(xiàn),。”(生物谷Bioon.com)
doi: 10.1200/JOP.2012.000811
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Diet of Australopithecus afarensis from the Pliocene Hadar Formation, Ethiopia
Jonathan G. Wynna,1,Matt Sponheimerb,William H. Kimbelc,Zeresenay Alemsegedd,Kaye Reedc,Zelalem K. Bedasoe, andJessica N. Wilsona
The enhanced dietary flexibility of early hominins to include consumption of C4/crassulacean acid metabolism (CAM) foods (i.e., foods derived from grasses, sedges, and succulents common in tropical savannas and deserts) likely represents a significant ecological and behavioral distinction from both extant great apes and the last common ancestor that we shared with great apes. Here, we use stable carbon isotopic data from 20 samples of Australopithecus afarensis from Hadar and Dikika, Ethiopia (>3.4–2.9 Ma) to show that this species consumed a diet with significant C4/CAM foods, differing from its putative ancestor Au. anamensis. Furthermore, there is no temporal trend in the amount of C4/CAM food consumption over the age of the samples analyzed, and the amount of C4/CAM food intake was highly variable, even within a single narrow stratigraphic interval. As such, Au. afarensis was a key participant in the C4/CAM dietary expansion by early australopiths of the middle Pliocene. The middle Pliocene expansion of the eastern African australopith diet to include savanna-based foods represents a shift to use of plant food resources that were already abundant in hominin environments for at least 1 million y and sets the stage for dietary differentiation and niche specialization by subsequent hominin taxa.
