人類到底是在哪里學(xué)會直立行走,？是森林還是草原,？最新的一項研究表明,，熱帶草原在人類進(jìn)化過程中所起的作用,，比之前認(rèn)為的要長久和明顯得多。
上世紀(jì)20年代提出的“草原說”認(rèn)為,，人類從森林向草原的過渡迫使人們直立行走,，同時腦容量增大，形成了人類的特性。該理論自提出以來不斷遭到質(zhì)疑,，有科學(xué)家指出,，東非原始人化石最多的地方其實覆蓋著多片林地，因此有很多人認(rèn)為人類是在森林里學(xué)會直立行走的,。
不過,，英國《自然》雜志刊登的新研究支持了“草原說”。美國猶他州立大學(xué)托爾·塞林教授領(lǐng)導(dǎo)的科研小組發(fā)現(xiàn),，每個發(fā)現(xiàn)有人類化石的地區(qū),，總有證據(jù)表明該地區(qū)當(dāng)時存在類似草原的空曠區(qū)，這說明大約400萬年前人類開始學(xué)行走的時候,，空曠的草原環(huán)境即已具備,，甚至對人類直立行走起到了主要的作用。(生物谷 Bioon.com)
doi:10.1038/nature10306
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Woody cover and hominin environments in the past 6[thinsp]million years
Thure E. Cerling; Jonathan G. Wynn; Samuel A. Andanje; Michael I. Bird; David Kimutai Korir; Naomi E. Levin; William Mace; Anthony N. Macharia; Jay Quade; Christopher H. Remien
The role of African savannahs in the evolution of early hominins has been debated for nearly a century. Resolution of this issue has been hindered by difficulty in quantifying the fraction of woody cover in the fossil record. Here we show that the fraction of woody cover in tropical ecosystems can be quantified using stable carbon isotopes in soils. Furthermore, we use fossil soils from hominin sites in the Awash and Omo-Turkana basins in eastern Africa to reconstruct the fraction of woody cover since the Late Miocene epoch (about 7 million years ago). 13C/12C ratio data from 1,300 palaeosols at or adjacent to hominin sites dating to at least 6 million years ago show that woody cover was predominantly less than ~40% at most sites. These data point to the prevalence of open environments at the majority of hominin fossil sites in eastern Africa over the past 6 million years.
