「最古」の墓を発見　初期ヒト属のものか　南ア

【マロペン（南アフリカ）ＡＦＰ＝時事】南アフリカのヨハネスブルク近郊で、初期ヒト属と考えられている「ホモ・ナレディ」による世界最古の「墓」を発見したとする査読前論文が５日、公表された。ホモ・ナレディは脳の容量が小さく、死者を埋葬するなどの「意味付けされた」複雑な活動はできないと考えられてきたため、人類の進化についての通説に疑問を投げ掛けるものとなる。（写真は南アフリカの遺跡群「人類のゆりかご」のライジング・スター洞窟の中を歩くリー・バーガー教授）
　著名な古人類学者リー・バーガー氏が率いる研究チームによると、ホモ・ナレディの骨はヨハネスブルク近郊の遺跡群「人類のゆりかご」のライジング・スター洞窟の地下約３０メートル地点に埋められていた。同遺跡群は国連教育科学文化機関（ユネスコ）の世界遺産に登録されている。
　研究チームは、「現生人類（ホモ・サピエンス）」による埋葬の証拠より少なくとも１０万年は古く、「ヒト亜科の記録では最古の墓」としている。
　これまでに最古とされている墓は中東とアフリカで発見された約１０万年前のもので、ホモ・サピエンスが埋葬されていた。しかし、今回バーガー氏らが発見した墓は、少なくとも紀元前２０万年前にさかのぼる。
　ホモ・ナレディはバーガー氏により発掘された。類人猿と現生人類の特徴を併せ持ち、脳の大きさはオレンジほどで、身長は約１．５メートル。指やつま先が湾曲し、道具の作製や直立歩行、木登りに適した手足を持ち、現生人類に至るこれまでの進化の通説を覆した。
　ホモ・ナレディの骨の化石は、２０１３年に初めて発見された。今回の研究対象となる楕円（だえん）形の墓は１８年に始まった発掘調査で見つかった。
　研究チームによれば、意図的に穴を掘り、遺体を埋めたとみられる形跡があり、穴には少なくとも５人の遺骨が埋められていた。
　研究チームは「今回の発見は、埋葬がホモ・サピエンスなど脳の容量が大きいヒト属だけの慣習ではなかったことを示している」と主張。さらなる分析が必要とした上で、「人類の進化についての理解が改められる」ことになるだろうとしている。【翻訳編集ＡＦＰＢＢＮｅｗｓ】
〔ＡＦＰ＝時事〕（2023/06/06-16:14）

Palaeontologists in South Africa said Monday they have found the oldest known burial site in the world, containing remains of a small-brained distant relative of humans previously thought incapable of complex behaviour.
Led by renowned palaeoanthropologist Lee Berger, researchers said they discovered several specimens of Homo naledi -- a tree-climbing, Stone Age hominid -- buried about 30 metres (100 feet) underground in a cave system within the Cradle of Humankind, a UNESCO world heritage site near Johannesburg.
These are the most ancient interments yet recorded in the hominin record, earlier than evidence of Homo sapiens interments by at least 100,000 years, the scientists wrote in a series of yet to be peer reviewed and preprint papers to be published in eLife.
The findings challenge the current understanding of human evolution, as it is normally held that the development of bigger brains allowed for the performing of complex, meaning-making activities such as burying the dead.
The oldest burials previously unearthed, found in the Middle East and Africa, contained the remains of Homo sapiens -- and were around 100,000 years old.
Those found in South Africa by Berger, whose previous announcements have been controversial, and his fellow researchers, date back to at least 200,000 BC.
Critically, they also belong to Homo naledi, a primitive species at the crossroads between apes and modern humans, which had brains about the size of oranges and stood about 1.5 metres (five feet) tall.
With curved fingers and toes, tool-wielding hands and feet made for walking, the species discovered by Berger had already upended the notion that our evolutionary path was a straight line.
Homo naledi is named after the Rising Star cave system where the first bones were found in 2013.
The oval-shaped interments at the centre of the new studies were also found there during excavations started in 2018.
The holes, which researchers say evidence suggests were deliberately dug and then filled in to cover the bodies, contain at least five individuals.
These discoveries show that mortuary practices were not limited to H. sapiens or other hominins with large brain sizes, the researchers said.
The burial site is not the only sign that Homo naledi was capable of complex emotional and cognitive behaviour, they added.
- Brain size -
Engravings forming geometrical shapes, including a rough hashtag figure, were also found on the apparently purposely smoothed surfaces of a cave pillar nearby.
That would mean not only are humans not unique in the development of symbolic practices, but may not have even invented such behaviours, Berger told AFP in an interview.
Such statements are likely to ruffle some feathers in the world of palaeontology, where the 57-year-old has previously faced accusations of lacking scientific rigour and rushing to conclusions.
Many balked when in 2015 Berger, whose earlier discoveries won support from National Geographic, first aired the idea that Homo naledi was capable of more than the size of its head suggested.
That was too much for scientists to take at that time. We think it's all tied up with this big brain, he said.
We're about to tell the world that's not true.
While requiring further analysis, the discoveries alter our understandings of human evolution, the researchers wrote.
Burial, meaning-making, even 'art' could have a much more complicated, dynamic, non-human history than we previously thought, said Agustin Fuentes, a professor of anthropology at Princeton University, who co-authored the studies.
Carol Ward, an anthropologist at the University of Missouri not involved in the research, said that these findings, if confirmed, would be of considerable potential importance.
I look forward to learning how the disposition of remains precludes other possible explanations than intentional burial, and to seeing the results once they have been vetted by peer review, she told AFP.
Ward also pointed out that the paper acknowledged that it could not rule out that markings on the walls could have been made by later hominins.