從海底打撈出的下顎骨擴大了神秘古人類物種的範圍（1/2）

 Recently CNN on-line reported the following:

Jawbone dredged up from the seafloor expands the range of a mysterious species of ancient human (1/2)

Katie Hunt, CNN

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

A fossilized jawbone dredged up by a fishing net from the seafloor 15 ½ miles (25 kilometers) off the coast of Taiwan in 2010 looked human, but for years scientists failed to nail down exactly where it fit in the human family tree.

Now, scientists have been able to confirm the identity of the mystery fossil, known as Penghu 1, through analyzing ancient protein fragments contained in teeth still attached to the jaw. The jawbone belonged to a Denisovan man, according to the findings published Thursday in the journal Science.

“We’ve determined and shown over the past couple of years that these proteins can survive longer than DNA does, and that if we have decent recovery, we can say something about the evolutionary ancestry of a specimen,” said study coauthor Frido Welker, an associate professor of biomolecular paleoanthropology at the University of Copenhagen’s Globe Institute in Denmark.

Fishermen working off the coast of Taiwan long have dredged up the bones of ancient animals — elephants, water buffalo and hyenas — in their nets, relics of an ice age past when sea levels were lower and the ocean channel was a land bridge.

The Denisovan man likely lived on this strip of land that once existed between what’s now China and Taiwan. This discovery establishes the third place that the enigmatic ancient humans first identified in 2010 were definitively known to have lived and shows that the Denisovans occupied a diverse range of environments: Siberian mountains, the high-altitude Tibetan Plateau and the humid subtropical latitudes, Welker added.

Unusual provenance

Fishermen who find fossils among their catch often sell their finds to antique shops, where collectors pick them up, said study coauthor Chun-Hsiang Chang, a curator of paleontology at Taiwan’s National Museum of Natural Science. The museum has thousands of fossils found from the seabed in its collection.

One collector brought the jawbone, now identified as Denisovan, to the museum wanting to know more about the specimen, and Chang said he immediately realized it was unusual and encouraged the collector to donate or sell the fossil to the museum, which he did.

A paper Chang coauthored in 2015 argued the fossil belonged to the genus Homo, the grouping to which our species, Homo sapiens, and other ancient humans such as Neanderthals belong, but colleagues were not able to extract any ancient DNA from the fossil and couldn’t verify the exact species.

It also wasn’t possible to date the fossil accurately. Scientists believe it has an age range of between 10,000 and 70,000 or 130,000 and 190,000 years old, dating the bone to a time when past sea levels in that vicinity were low.

Chang took the specimen to Copenhagen in 2022 hoping to learn more from Welker and other scientists who were pioneering techniques to extract proteins from fossils, a field known as paleoproteomics.

Chang recalled airport security in Copenhagen stopping him when the case containing the jawbone passed through an X-ray machine. “They stopped me and wanted me to open (the case),” he said. “I thought maybe they were going to arrest me.” Chang said he was allowed to leave only after sharing his credentials and giving the security personnel “a very short human evolution lesson.”

Before testing the jawbone, Welker and his colleagues sampled an elephant bone and pig bone from the same part of the seabed to work out which extraction methods would work best and determine whether proteins were still present. The team found proteins and proceeded with extracting them.

Two amino acid sequences from the proteins recovered from the specimen matched those known from the Denisovan genome — a complete set of genetic information sequenced from DNA. What’s more, the lab work detected a type of protein with a sex-specific peptide called amelogenin, and Y-chromosome specific peptides revealed that the Denisovan individual was male, Welker said.

(to be continued)

Translation

從海底打撈出的下顎骨擴大了神秘古人類物種的範圍（1/2）

2010 年，在距台灣海岸 15.5 英里（25 公里）的海底, 一塊看起來像是人類頜骨的化石被漁網打撈出，但多年來科學家們一直未能確定它在人類家族樹中的確實位置。

現在，科學家們透過分析仍附著在下顎骨上的牙齒中所含的古代蛋白質碎片，已經能夠確認這塊被稱為澎湖 1 號的神秘化石的身份。根據週四發表在《科學》雜誌上的研究結果，這塊下顎骨屬於一個 Denisovan 人的。

研究結果合著者、丹麥哥本哈根大學地球研究所生物分子古人類學副教授 Frido Welker 說: 「我們在過去幾年中已經確定並證明，這些蛋白質可以比 DNA 存活更長時間，如果我們能夠進行良好的恢復，我們就可以了解標本的進化祖先」。

長期以來，在台灣沿海作業的漁民在漁網中撈出了大象、水牛和鬣狗等古代動物的骨頭，這些都是過去冰河時代的遺跡，當時海平面較低，海峽是一座陸橋。

Denisovan人很可能生活在這片曾經位於現在的中國和台灣之間的土地上。Welker補充道，這項發現確立了 在2010 年首次被發現的神秘古人類的第三個曾確實地居住的地方，並表明 Denisovan人曾生活在各種各樣的環境中：西伯利亞山脈、高海拔的青藏高原和濕潤的亞熱帶緯度地區。

 

不尋常的來源

台灣國立自然科學博物館古生物學館長、該研究的共同作者 Chun-Hsiang Chang 說，在捕撈到的魚中發現化石的漁民通常會把這些化石賣給古董店，然後收藏家們就會把化石買走。博物館收藏了數千件從海底發現的化石。

一位收藏家將這塊現已被確認為 Denisovan人的頜骨帶到了博物館，想要了解更多關於該標本的信息。Chang說，他立即意識到這塊頜骨很不尋常，並鼓勵這位收藏家將化石捐贈或出售給博物館，而這位收藏家也這麼做了。

2015 年，Chang 與他人合作撰寫了一篇論文，認為化石是屬於人屬。我們人類、智人以及Neanderthals人等其他古人類都屬於這一類，但同事們無法從化石中提取任何古代 DNA，也無法驗證其確實物種。

化石的年代也無法準確地確定。科學家認為，這塊骨頭的年齡在 10,000 至 70,000 年或 130,000 至 190,000 年之間，可以追溯到過去該地區海平面較低的時期。

2022 年，Chang 將標本帶到了哥本哈根，希望從 Welker 和其他開創從化石中提取蛋白質技術的科學家那裡得知更多，這一領域被稱為古蛋白質組學。

Chang回憶說，當裝有顎骨的箱子通過 X 光機時，哥本哈根機場的保全人員攔住了他。他說: 「他們攔住了我，要我打開（這個箱子）」; 「我以為他們可能會逮捕我」。Chang 再說，在他向安保人員提供了他的證件並給他們上了「一堂非常簡短的人類進化課」之後，他才被允許離開。

在向這下顎骨進行測試之前，Welker和他的同事, 用從同一區海底採集的象骨和豬骨作為樣辦，以確定哪種抽取方法效果最好，並可確定是否仍有蛋白質存在。研究小組是發現了蛋白質並著手提取它。

從標本中提取的蛋白質的兩個氨基酸序列與已知的 Denisovan人基因組序列相符 - 這是由 DNA 測序而成的一整套遺傳訊息。此外，Welker說, 實驗室研究還檢測到一種含有性別特異性勝肽（稱為牙釉蛋白）的蛋白質，而因其含有Y 染色體特異性勝肽則顯示這 Denisovan人是男性。

（待續）

Note:

1. Land bridge (陸橋)in this context is a land link between two land masses or continents, usually used in geography or ecology to describe the spread and movement of species. (Gemini)