從海底打撈出的顎骨擴大了神秘古人類物種的範圍（2/2）

Recently CNN on-line reported the following:

Jawbone dredged up from the seafloor expands the range of a mysterious species of ancient human (2/2)

Katie Hunt, CNN

Thu, April 10, 2025 at 1:18 p.m. PDT·7 min read

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Denisovan paradox

Denisovans were first identified in 2010 in a lab using DNA sequences extracted from a tiny fragment of finger bone found in Denisova Cave in Siberia’s Altai Mountains, which is how the group got its name.

Genetic analysis subsequently revealed that the Denisovans, like Neanderthals, had once interbred with early modern humans. Traces of Denisovan DNA found in present-day people suggest the ancient species likely once lived across much of Asia, and the recent discovery of Denisovan fossils from outside their namesake cave has begun to show they occupied a wide range of places in Asia.

In 2019, scientists shared news that a jawbone found in a cave on the northeastern edge of the Tibetan Plateau, known as the Xiahe mandible, contained a Denisovan molecular signature. A Denisovan rib bone from the same cave was reported in 2024.

In 2022, scientists identified a tooth unearthed at a cave in Laos as Denisovan because it closely resembled the tooth from the Xiahe mandible. The clue placed the species in Southeast Asia for the first time, though scientists were not able to get any definitive molecular information from the molar to confirm it.

The good preservation of the proteins in the Penghu 1 mandible is surprising, given that it had been at the bottom of the sea for a long time, said archaeologist Zhang Dongju, a professor at China’s Lanzhou University who worked on the Xiahe jawbone. She was not involved in the study.

“With the accumulation of Denisovan fossils and the increase of Denisovan-specific molecular signature identified, identification of Denisovan fossils will be easier,” she said. “And I believe more Denisovan fossils will be found and identified in (the) future. And we will know more about this mysterious species.”

Katerina Douka, an associate professor in archaeological science at Austria’s University of Vienna, described Denisovans as a paradox because scientists have detailed genetic information about the species but few fossils, so little is known about how they looked, although she noted they had “exceptionally large” molars.

The Penghu 1 and Xiahe mandibles did not have wisdom teeth, which could indicate that their jaws did not protrude forward in their face, said Ryan McRae, a paleoanthropologist at the Smithsonian National Museum of Natural History in Washington, DC.

“Neither mandible has a chin, like modern humans do, so the front of their jawline would probably look flatter than ours,” McRae said by email. “The authors wisely point out that the Penghu mandible is male, which means that it may exhibit the larger, more robust end of variation for this species. In other words, female Denisovans could look the same, or quite different, we just don’t know yet.”

Douka and McRae weren’t involved in the study.

The mysterious humans don’t have a widely accepted official species name yet, although some scientists have suggested Homo juluensis, a classification that groups Denisovan fossils with other fossils from China, including “dragon man,” a skull described in 2021.

Chang said that he and his colleagues hope to revisit the 4,000 or so fossils in the National Museum of Natural Science’s collection that have been gathered from the seabed in the Taiwan Strait over the past 40 to 50 years and use the same proteomic methods applied to the Penghu 1 jawbone to investigate whether any other fragments belong to Denisovans.

“Maybe inside my collection there’s some treasure we don’t know about,” Chang said.

Translation

從海底打撈出的顎骨擴大了神秘古人類物種的範圍（2/2）

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Denisovan人論的矛盾

2010 年，實驗室首次透過從西伯利亞阿爾泰山 Denisova 洞穴中發現的一小塊指骨碎片中提取的 DNA 序列而發現了Denisovan人，該群體的名字也由此而來。

隨後的基因分析表明，Denisovan人與尼安德特人一樣，曾經與早期現代人類雜交。在現代人身上發現的 Denisovan人 DNA 痕跡表明，這個古老的物種可能曾經生活在亞洲大部分地區，而最近在以他們命名的洞穴外發現的 Denisovan人化石開始表明他們曾經居住在亞洲的廣泛地區。

2019 年，科學家分享了一條訊息，在青藏高原東北邊緣的一個洞穴中發現的一塊頜骨, 後被稱為夏河下顎骨, 含有 Denisovan人的分子特徵。 2024 年，有人報告在同一洞穴中發現了Denisovan人的肋骨。

2022年，科學家鑑定出在寮國一處洞穴出土的一顆牙齒為 Denisovan人牙齒，因為它與夏河下顎骨的牙齒非常相似。這一線索首次將該物種定位在東南亞，儘管科學家無法從這臼齒中獲得任何明確的分子資訊來證實這一點。

研究夏河顎骨的蘭州大學考古學家 Zhang Dongju 教授表示，考慮到澎湖1號下顎骨在海底沉睡了很長一段時間，其蛋白質能保存完好令人吃驚。她沒有參與這項研究。

她說： “隨著Denisovan人化石的積累和 Denisovan人特異分子特徵的識別增加，Denisovan人化石的鑑定將變得更加容易”; “我相信未來會發現並鑑定出更多Denisovan人的化石。我們也會對這個神秘物種有更多的了解。”

奧地利維也納大學考古學副教授 Katerina Douka 認為 Denisovan 人是一個矛盾，因為科學家掌握了該物種的詳細基因信息，但卻沒有太多化石，因此對他們的外貌知之甚少，儘管她指出他們有「異常大」的臼齒。

華盛頓特區 Smithsonian 國家自然歷史博物館的古人類學家 Ryan McRae 說，澎湖1號和夏河下顎骨沒有智齒，這可能表明他們的下顎沒有在臉上向前突出。

McRae 在電子郵件中表示：「下顎骨也沒有下巴, 像現代人類那樣子，所以它們的下顎線前部可能看起來比我們的更平坦」; 「作者明智地指出，澎湖人的下顎骨屬於雄性，這意味著它可能展現出該物種更大、更強壯的變異。換句話說，雌性 Denisovan人可能看起來相同，也可能截然不同，我們只是目前尚不清楚」。

Douka 和 McRae 並沒有參與這項研究。

這些神秘人類目前還沒有一個被廣泛接受的官方物種名稱，儘管一些科學家建議將其命名為 Homo juluensis，這種分類將 Denisovan人化石與來自中國的其他化石歸為一類，其中包括「龍人」, 即2021 年描述的一個人頭骨。

Chang 表示，他和同事希望重新審視國立自然科學博物館過去四十到十五年來從台灣海峽海底收集的大約 4,000 塊化石，並使用與澎湖 1 號頜骨相同的蛋白質組學方法來研究其他碎片是否屬於Denisovan人。

Chang 說: 「也許我的收藏裡面還有一些我們不知道的寶藏」。

So, a fossilized jawbone that was dredged up by a fishing net off the coast of Taiwan in 2010 looked human. Now, scientists are able to confirm that this mystery fossil jawbone should belong to a Denisovan male. So far, little is known about how Denisovans would look like. I am eager to know the outcome of further research on them.