終於揭曉印尼哈比人的起源

原文網址：www.sciencedaily.com/releases/2017/04/170421084917.htm

印尼哈比人的起源終於揭曉了

佛羅勒斯人(Homo floresiensis)是2003年發現於印尼佛羅勒斯島上的一個矮小人種。對其骸骨進行的最詳盡研究發現他們極有可能是從生活在非洲的祖先演化而成，並非許多人認為的直立人(Homo erectus)。

佛羅勒斯人因其矮小的身材而被暱稱為「哈比人」。由澳洲國立大學進行的研究發現他可能是巧人(Homo habilis)的姊妹種。巧人是發現於非洲，生活在175萬年前的已知最早人種之一。

生活在該區域的早期人類只有另外一種――直立人，其化石發現於印尼爪哇主島上。研究數據得出的結論顯示沒有任何證據可以支持流行理論中，佛羅勒斯人是由體型大上許多的直立人演化而來的說法。

主要作者，澳洲國立大學考古與人類學院的Debbie Argue博士，表示研究結果應該能幫助自佛羅勒斯人發現以來就倍受熱議的爭論平息下來。

「分析顯示在家族樹上，佛羅勒斯人可能是巧人的姊妹種，意謂著他們倆可能擁有同樣一名祖先。」Argue博士說。

「佛羅勒斯人可能是先在非洲演化出來之後才遷移，或者是其共祖離開非洲後才在某處演化成佛羅勒斯人。」

已知佛羅勒斯人直到54000年前的晚近都還生活在佛羅勒斯島上。

澳洲國科會在2010年通過此研究，使研究人員得以探討這個新發現的物種在人類演化樹上的地位為何。

過往的研究大都著重在顱骨以及下顎，此研究的133個資料點則涵蓋了顱骨、雙顎、牙齒、手臂、腿部和肩膀。

Argue博士說沒有任何一項數據可以支持佛羅勒斯人是從直立人演化而成的理論。

「我們檢視過佛羅勒斯人是否可以源自於直立人。」她說。

「我們發現如果你試著將他們在家族樹上連結起來，會得到相當站不住腳的結果。所有測試都顯示這項假說不符合實情――完全是個不可行的理論。」

Argue博士說許多特徵呈現出來的事實可以支持他們的結論，像是顎部的結構：佛羅勒斯人比直立人原始許多。

「從邏輯上很難去理解這樣的退化如何發生――為什麼直立人的顎部會往回演變成我們在佛羅勒斯人身上看到的原始型態？」

Argue博士表示分析也支持佛羅勒斯人分支出來時間較早的理論，大概早於175萬年以前。

她說：「如果佛羅勒斯人確實比最早的巧人還要先演化出來，那他看起來必然會相當原始。」

福林德斯大學和南澳大利亞博物館的Mike Lee教授利用統計模型來分析數據。

Lee教授表示：「當我們進行分析便得到明確的結果支持佛羅勒斯人和巧人的關係，佛羅勒斯人在人類演化樹上佔據的位置相當原始。」

Lee教授表示：「我們99%可以確定佛羅勒斯人跟直立人沒有關係，而且將近100%確定他並不是畸形的智人。」

Origins of Indonesian Hobbits finally revealed

The most comprehensive study on the bones of Homo floresiensis, a species of tiny human discovered on the Indonesian island of Flores in 2003, has found that they most likely evolved from an ancestor in Africa and not from Homo erectus as has been widely believed.

The study by The Australian National University (ANU) found Homo floresiensis, dubbed "the hobbits" due to their small stature, were most likely a sister species of Homo habilis -- one of the earliest known species of human found in Africa 1.75 million years ago.

Data from the study concluded there was no evidence for the popular theory that Homo floresiensis evolved from the much larger Homo erectus, the only other early hominid known to have lived in the region with fossils discovered on the Indonesian mainland of Java.

Study leader Dr Debbie Argue of the ANU School of Archaeology & Anthropology, said the results should help put to rest a debate that has been hotly contested ever since Homo floresiensis was discovered.

"The analyses show that on the family tree, Homo floresiensis was likely a sister species of Homo habilis. It means these two shared a common ancestor," Dr Argue said.

"It's possible that Homo floresiensis evolved in Africa and migrated, or the common ancestor moved from Africa then evolved into Homo floresiensis somewhere."

Homo floresiensis is known to have lived on Flores until as recently as 54,000 years ago.

The study was the result of an Australian Research Council grant in 2010 that enabled the researchers to explore where the newly-found species fits in the human evolutionary tree.

Where previous research had focused mostly on the skull and lower jaw, this study used 133 data points ranging across the skull, jaws, teeth, arms, legs and shoulders.

Dr Argue said none of the data supported the theory that Homo floresiensis evolved from Homo erectus.

"We looked at whether Homo floresiensis could be descended from Homo erectus," she said.

"We found that if you try and link them on the family tree, you get a very unsupported result. All the tests say it doesn't fit -- it's just not a viable theory."

Dr Argue said this was supported by the fact that in many features, such as the structure of the jaw, Homo floresiensis was more primitive than Homo erectus.

"Logically, it would be hard to understand how you could have that regression -- why would the jaw of Homo erectus evolve back to the primitive condition we see in Homo floresiensis?"

Dr Argue said the analyses could also support the theory that Homo floresiensis could have branched off earlier in the timeline, more than 1.75 million years ago.

"If this was the case Homo floresiensis would have evolved before the earliest Homo habilis, which would make it very archaic indeed," she said.

Professor Mike Lee of Flinders University and the South Australian Museum, used statistical modeling to analyse the data.

"When we did the analysis there was really clear support for the relationship with Homo habilis. Homo floresiensis occupied a very primitive position on the human evolutionary tree," Professor Lee said.

"We can be 99 per cent sure it's not related to Homo erectus and nearly 100 per cent chance it isn't a malformed Homo sapiens," Professor Lee said.

原始論文：Debbie Argue, Colin P. Groves, Michael S.Y. Lee, William L. Jungers. The affinities of Homo floresiensis based on phylogenetic analyses of cranial, dental, and postcranial characters. Journal of Human Evolution, April 2017 DOI: 10.1016/j.jhevol.2017.02.006

引用自：Australian National University. "Origins of Indonesian Hobbits finally revealed." ScienceDaily. ScienceDaily, 21 April 2017.