中国で化石発見の「竜人」　現生人類の最近縁種か　論文発表

【ワシントンＡＦＰ＝時事】中国北東部・黒竜江省で見つかった頭骨化石が、１４万年以上前の新種人類のものであることが判明したとする論文が２５日、発表された。これまで現生人類（ホモ・サピエンス）に最も近いとされていたネアンデルタール人よりも現生人類に近い種とされ、人類の進化史を根本から書き換える可能性がある。（写真は「ホモ・ロンギ」の想像図）
　頭骨化石は１９３３年、黒竜江省ハルビンで見つかったが、日本軍から守るために８５年間にわたり地中に隠されていたとされる。２０１８年に掘り起こされ、河北地質大学の季強教授の手に渡った。研究チームはこの新種を、発見地域の名前である竜江にちなんで、「ホモ・ロンギ」（竜人の意）と名付けた。
　科学誌イノベーションに掲載された３本の論文によると、頭骨化石は少なくとも１４万６０００年前の中期更新世のものと判明。現生人類に比べて脳容量は変わらない一方で、眼窩（がんか）は大きく、眉弓が分厚いほか、口の幅が広く、歯が大きい。木々のある氾濫原に住んでいた５０歳前後の男性のものとみられる。
　論文の共著者である英ロンドン自然史博物館のクリス・ストリンガー教授はＡＦＰに対し、「この集団は狩猟採集民だっただろう」と説明。「現代のハルビンの冬の気温からして、ネアンデルタール人よりも厳しい寒さに対処していたようだ」と話した。
　研究チームは、頭骨化石が見つかった場所や、頭骨から推定される体の大きさから、ホモ・ロンギが過酷な環境に適応し、アジア全域に広まることができたと考えている。同時期にホモ・サピエンスが東アジアに到達していれば、両種が交雑した可能性もあるが、交雑が実際に起きたかは不明だ。【翻訳編集ＡＦＰＢＢＮｅｗｓ】

〔ＡＦＰ＝時事〕（2021/06/29-13:55）

A skull preserved almost perfectly for more than 140,000 years in northeastern China represents a new species of ancient people more closely related to us than even Neanderthals -- and could fundamentally alter our understanding of human evolution, scientists announced Friday.
It belonged to a large-brained male in his 50s with deep set eyes and thick brow ridges. Though his face was wide, it had flat, low cheekbones that made him resemble modern people more closely than other extinct members of the human family tree.
The research team has linked the specimen to other Chinese fossil findings and is calling the species Homo longi or Dragon Man, a reference to the region where it was discovered.
The Harbin cranium was first found in 1933 in the city of the same name but was reportedly hidden in a well for 85 years to protect it from the Japanese army.
It was later dug up and handed to Ji Qiang, a professor at Hebei GEO University, in 2018.
On our analyses, the Harbin group is more closely linked to H. sapiens than the Neanderthals are -- that is, Harbin shared a more recent common ancestor with us than the Neanderthals did, co-author Chris Stringer of the Natural History Museum, London told AFP.
This, he said, would make Dragon Man our sister species and a closer ancestor of modern man than the Neanderthals.
The findings were published in three papers in the journal The Innovation.
The skull dates back at least 146,000 years, placing it in the Middle Pleistocene.
While it shows typical archaic human features, the Harbin cranium presents a mosaic combination of primitive and derived characters setting itself apart from all the other previously named Homo species, said Ji, who led the research.
The name is derived from Long Jiang, which literally means Dragon River.
Dragon Man probably lived in a forested floodplain environment as part of a small community.
This population would have been hunter-gatherers, living off the land, said Stringer. From the winter temperatures in Harbin today, it looks like they were coping with even harsher cold than the Neanderthals.
Given the location where the skull was found as well as the large-sized man it implies, the team believe H. longi may have been well adapted for harsh environments and would have been able to disperse throughout Asia.
- Family tree -
Researchers first studied the cranium, identifying over 600 traits they fed into a computer model that ran millions of simulations to determine the evolutionary history and relationships between different species.
These suggest that Harbin and some other fossils from China form a third lineage of later humans alongside the Neanderthals and H. sapiens, explained Stringer.
The other findings include a fossilized skull from the Chinese province of Dali that is thought to be 200,000 years old and was found in 1978, and a jaw found in Tibet dating to 160,000 years ago.
Stringer explained that his Chinese colleagues had decided upon the name H. longi, which he called a great name, but said he would have been equally happy to refer to the species as H. Daliensis, which was previously used for the Dali cranium.
More than 100,000 years ago, several human species coexisted across Eurasia and Africa, including our own, Neanderthals and Denisovans, a recently discovered sister species to Neanderthals. Dragon man might now be added to that list.
An alternative explanation is that H. longi and Denisovans are in fact one and the same. Fossils so far attributed to Denisovans include teeth and bones but not a full skull, so scientists are unsure what they looked like.
But Neanderthals and Denisovans were genetically closer to each other than to Sapiens, while the new study suggests H. longi were more anatomically similar to us than Neanderthals.
The lingering uncertainty may therefore require future genetic sequencing to help clear up.