Recently CNN news reported the following:
Cave discovery in France may explain why Neanderthals
disappeared, scientists say (1/2)
Katie Hunt, CNN
Thu, September 12, 2024 at 7:11 a.m. PDT·5 min read
When archaeologist Ludovic Slimak unearthed five teeth in a
rock shelter in France’s Rhône Valley in 2015, it was immediately obvious that
they belonged to a Neanderthal, the first intact remains of the ancient species
to be discovered in that country since 1979.
However, the once-in-a-lifetime find, nicknamed Thorin after a character in “The Hobbit,” remained a well-kept secret for almost a decade while Slimak and his colleagues untangled the significance of the find — a fraught undertaking that pitted experts in ancient DNA against archaeologists.
“We faced a major issue,” said Slimak, a researcher at France’s National Centre for Scientific Research and Paul Sabatier University in Toulouse. “The genetics was sure the Neanderthal we called Thorin was 105,000 years old. But we knew by (the specimen’s) archaeological context that it was somewhere between 40,000 to 50,000 years old.”
“What the DNA was suggesting was not in accordance with what we saw,” he added.
It took the team almost 10 years to piece together the story of the puzzling Neanderthal, adding a new chapter in the long-standing mystery of why these humans disappeared around 40,000 years ago.
The research, published Wednesday in the journal Cell Genomics, found that Thorin belonged to a lineage or group of Neanderthals that had been isolated from other groups for some 50,000 years. This genetic isolation was the reason Thorin’s DNA seemed to come from an earlier time period than it actually did.
“The Thorin population spent 50,000 years without exchanging genes with other Neanderthal populations,” Slimak said in a news release.
“We thus have 50 millennia during which two Neanderthal populations, living about ten days’ walk from each other, coexisted while completely ignoring each other.”
Slimak said that the discovery suggested that Neanderthal communities were small and insular — factors that could be key to understanding their extinction because isolation is generally considered to be an evolutionary disadvantage.
Less genetic variation could make it harder to adapt to changing climate or disease, while less social interaction between groups makes it harder to share knowledge and technology.
“They were happy in their valley and did not need to move, while Homo sapiens all the time they want to explore, to see what is there after this river, after this mountain. (We have) this need, this need to move, and this need to build a social network,” Slimak said.
This pattern of small populations, isolated culturally and genetically from one another, was likely a major factor behind Neanderthal extinction, which occurred around the same time Homo sapiens arrived in Europe, he said.
(to be continued)
Translation
科學家表示，法國發現的洞穴可能解釋了尼安德特人消失的原因
(1/2)
2015 年，當考古學家Ludovic
Slimak 在法國羅納河谷的一個岩石掩體中挖掘出五顆牙齒時，人們立即發現它們屬於尼安德特人，這是自1979
年以來在該國發現的第一個完整的古代物種遺骸。
然而，這個千載難逢的發現，以《哈比人》中的一個角色命名為Thorin，在近十年的時間裡當Slimak和他的同事們去解開了這項發現的重要性時, 這一直是個嚴格保守的秘密 - 這是一項充滿挑戰的事，它導至古代DNA專家去抗衡考古學家。
法國國家科學研究中心和圖盧茲Paul
Sabatier大學的研究員Slimak說:「我們面臨一個重大問題」。 「遺傳學證實我們稱之為Thorin的尼安德塔人是
105,000 年前的。但（標本）在考古學上，我們知道它的年份是在 40,000 到 50,000 年前的。
他補充道:「DNA 的提示與我們所看到的不符」。
研究小組花了近 10 年的時間才拼湊出令人費解的尼安德特人的故事，為這些人類為何在 4 萬年前左右消失的長期謎團增添了新的篇章。
這項研究於週三發表在《細胞基因組學》雜誌上，發現Thorin屬於尼安德特人的一個譜系或群體，該譜系或群體與其他群體隔離了大約 5 萬年。這種基因隔離是令Thorin的 DNA 看來比實際更早時期的原因。
到目前為止，遺傳學家認為在尼安德特人滅絕時, 只得一個在基因上同質的群種，但新的研究表明當時西歐至少存在兩個群種 - 而且他們的生活距離驚人地接近。
Slimak在一份新聞稿中說: 「Thorin人族群已經有 5
萬年沒有與其他尼安德特族群交換基因」。
「因此，我們有 5 萬年的時間，兩個尼安德特人共存，彼此住所相距約十天的步行路程，卻完全忽視了對方」。
Slimak說，這項發現顯示尼安德特人的群落規模較小且與世隔絕 - 這些因素可能是了解其滅絕的關鍵因素，因為孤立通常被認為是不利進化。
較少的遺傳變異可能會使適應不斷變化的氣候或疾病變得更加困難，而群體之間較少的社會互動會使分享知識和技術變得更加困難。
Slimak說: 「他們在山谷裡很快樂，不需要搬家，而智人卻一直想探索，看看這條河之後、這座山之後會有什麼。 （我們有）這種需求，這種遷移的需求，以及建立社交網路的需求」。
他說，這種在文化和基因上相互隔離的小群體模式可能是尼安德特人滅絕的一個主要因素，這場滅絕大約發生在智人到達歐洲之時。
（待續）
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